ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/cpm/walnut-creek-CDROM/CPM/MODEMS/MODEM/X25.ARK/X25UM.DOC

Text File | 1986-07-28 | 67KB | 1,652 lines

********************************************************
*                                                      *
*        X.25 Protocol Interface for CP/M-80           *
*                                                      *
*                  USER MANUAL                         *
*                                                      *
*   (C) 1985  Ed Elizondo                              *
*             6 Cypress Court                          *
*             East Windsor, NJ 08520                   *
*                                                      *
*   NOTICE:  All Rights Reserved - These programs and  *
*   accompanying documentation may be used freely for  *
*   non-commercial applications.  They may not be sold *
*   or used for commercial applications without the    *
*   written permission of the author.                  *
*                                                      *
********************************************************



1.  Description of System

     Thσá softwarσá systeφá describeΣ hereiε enable≤ ßá Z8░á CP/═ ì
baseΣáá microcompute≥áá t∩á communicatσá witΦá ßáá networδáá datß ì
communication≤ equipmen⌠ (DCE⌐ por⌠ usinτ thσ X.2╡á internationa∞ ì
packe⌠áá communication≤á protocol«áá Thσá systeφá implement≤á thσ ì
function≤ oµ ß singlσ logica∞ channe∞ datß terminatinτá equipmen⌠ ì
(DTE⌐ anΣ i≤ capablσ oµ operatinτ eithe≥ iε ß termina∞ modσ o≥ iε ì
ßáá filσá transfe≥á modσá independentl∙á fo≥á eacΦá directioεá oµ ì
transmission.

     Iεá termina∞á mode¼á message≤á typeΣ a⌠á thσá loca∞á consolσ ì
keyboarΣá arσ transmitteΣ t∩ thσ networδ a≤ datß packet≤ a≤á sooε ì
a≤á ß carriagσ returε i≤ entered«á  Incominτ packe⌠ message≤á arσ ì
displayeΣ oε thσ loca∞ consolσ a≤ accepted.

     Iεá thσá filσá transfe≥ mode¼á thσ systeφ wil∞á transmi⌠á o≥ ì
receivσá file≤á oµá datß t∩ o≥á froφá thσá network«á  sincσá eacΦ ì
directioεá oµá transmissioεá i≤á handleΣá independently¼áá i⌠á i≤ ì
possiblσá t∩ transmi⌠ ß filσ whilσ receivinτ iε termina∞ modσá o≥ ì
viceversa«á  I⌠á i≤á als∩á possiblσá t∩á utilizσá thσá systeφá iε ì
bidirectional file transfer mode.



2.  Installation

     Thσá curren⌠ versioε oµ thi≤ softwarσ packagσ i≤á customizeΣ ì
t∩á ruεá oε thσ Digita∞ ResearcΦ Computer'≤á "Biτá Boardóá singlσ ì
boarΣá computer«á Thσá minimuφá hardwarσ requirement≤ arσá ßá Z8░ ì
microprocessor¼á ßá Ziloτá SI╧ seria∞ communication≤ por⌠á anΣá ß ì
Ziloτá CT├á counter/timer¼áá al∞á interfaceΣá usinτá Z8░á modσá ▓ ì
interrupts«

     Installatioεá oµ thσ systeφ oε thσ Digita∞á Research'≤á "Biτ ìèBoardó microcompute≥ systeφ consist≤ oµ a⌐ cuttinτ ß tracσ oε thσ ì
P├á boarΣá t∩á permi⌠ SIO-┴ t∩ operatσ correctl∙á iεá synchronou≤ ì
mode¼ b⌐ installinτ thσ appropriatσ jumper≤ t∩ configurσ thσ SIO-ì
┴á por⌠á t∩á properl∙á interfacσ t∩á thσá externa∞á networδá por⌠ ì
connection¼ anΣ c⌐ generatinτ thσ executalbσ X25.CO═ file.



2.1  Sync Jumper Removal

     A≤á receiveΣá froφ thσ manufacturer¼á pin≤ 1▒ (sync⌐ anΣá 1▓ ì
(receiveΣá data⌐á oµá SIO-┴á (U113⌐á arσá connecteΣá togethe≥á t∩ ì
facilitatσá automatiπ determinatioε oµ bauΣ ratσ wheε ßá standarΣ ì
(asynchronous⌐áá termina∞á i≤á connecteΣá t∩áá thi≤áá port«áá  Iε ì
synchronou≤á mode¼á thσá synπ termina∞ oµ thσ SI╧ operate≤ a≤á aε ì
outpu⌠á and¼á iµ lef⌠ connected¼á generate≤ undesireΣ transition≤ ì
whicΦ arσ superimposeΣ oε thσ inpu⌠ data«á  Fo≥ prope≥á operatioε ì
this printed circuit board trace must be cut.



2.2  SIO-A I/O Jumper Configuration

     Figurσá 2-▒á show≤á thσ I/╧ strappinτá jumper≤á requireΣá oε ì
connecto≥á JB┤ oµ thσ "Biτ Boardó t∩ configurσ SIO-┴ t∩ interfacσ ì
witΦ ß typica∞ maiε framσ X.2╡ port«á  Thσ jumper≤ configurσá thσ ì
"Biτá Boardó a≤ aε RS232├ "modemó usinτ al∞ RS232├ statu≤ signal≤ ì
(CTS¼á RTS¼á DC─ anΣ DTR⌐ anΣ witΦ thσ "Biτ Boardó supplyinτá thσ ì
bauΣ ratσ clocδ t∩ thσ "terminaló (main frame)«  Othe≥ hardwarσ ì
configuration≤ ma∙ requirσ ß differen⌠ jumpe≥ arrangement«á  Notσ ì
tha⌠á thσá samσá clocδ sourcσ mus⌠ bσ useΣ fo≥ thσá SI╧á anΣá thσ ì
externa∞á device¼á whethe≥ supplieΣ b∙ thσ "Biτ Boardó o≥ b∙á thσ ì
externa∞ device.



2.3  Generating the X25.COM File

     T∩á generatσá thσá X25.CO═ filσ fo≥á thσá "Biτá Board"¼á thσ ì
followinτ step≤ arσ necessary:

     a⌐á  Assemblσ thσ followinτ file≤ usinτ thσ Digita∞ ResearcΦ ì
RMA├á assemble≥ anΣ thσ Digita∞ ResearcΦ standarΣá SEQIO.LI┬á anΣ ì
Z80.LI┬ macr∩ libraries:

               X25.ASM
               LEVEL1.ASM
               LEVEL2.ASM
               LEVEL3.ASM
               FILES.ASM
               BUFFERS.ASM
               XUTIL.ASM

     b⌐á  Generatσá thσá X25.CO═ filσ b∙ linkinτ thσá .RE╠á file≤ ì
resultinτ froφ ste≡ a⌐ usinτ thσ Digita∞ ResearcΦ LINK-8░á linke≥ ìèusing the following command sequence:

     LINK x25,xutil,level1,level2,level3,buffers,files{a,nr]

     Notσá tha⌠á thσá X2╡ modulσ mus⌠ bσ linkeΣá firs⌠á sincσá i⌠ ì
contain≤ thσ prograφ entr∙ point«  Thσ orde≥ oµ linkinτ thσ othe≥ ì
module≤ i≤ immaterial.

     Fo≥ othe≥ hardwarσ configurations¼á ß ne≈ LEVEL1.AS═á modulσ ì
mus⌠ bσ generateΣ witΦ thσ appropriatσ hardwarσ interface≤ (refe≥ ì
to Section 6).


.paè    /------------baud rate generator supplies modem with tx clock
    |
    | /----------modem supplies SIO with TX clock
    | |
    | | /--------baud rate generator supplies SIO with TX clock
    | | |
    | | | /------modem supplies SIO with RX clock
    | | | |
    | | | | /----baud rate generator supplies SIO with RX clock
    | | | | |
    | | | | | /--baud rate generator supplies modem with RX clock
    | | | | | |
    | | | | | |
39  o o o o o o o o o o o o o o o o o o o o  1
    |   |   | |   |   |   |   |   |   |
40  o o o o o o o o o o o o o o o o o o o o  2
                | | | | | | | | | | | |
                | | | | | | | | | | | |
                | | | | | | | | | | | \----(M) RXD to pin 3
                | | | | | | | | | | |
                | | | | | | | | | | \------(T) TXD to pin 2
                | | | | | | | | | |
                | | | | | | | | | \--------(M) TXD from pin 3
                | | | | | | | | |
                | | | | | | | | \----------(T) RXD from pin 3
                | | | | | | | |
                | | | | | | | \------------(M) CTS to pin 5
                | | | | | | |
                | | | | | | \--------------(T) RTS to pin 4
                | | | | | |
                | | | | | \----------------(M) RTS from pin 4
                | | | | |
                | | | | \------------------(T) CTS from pin 5
                | | | |
                | | | \--------------------(M) DCD to pin 8
                | | |
                | | \----------------------(T) DTR to pin 20
                | |
                | \------------------------(M) DTR from pin 20
                |
                \--------------------------(T) DCD from pin 8


                             LEGEND

(M) indicates RS232C modem configuration of the "Big Board"
(T) indicates RS232C terminal configuration of the "Big Board"

RXD = received data                TXD = transmitted data
RTS = request to send              CTS = clear to send
DTR = data terminal ready          DCD = data carrier detect

            Figure 2-1 - SIO-A I-O Strapping Options
.paè3.  Initialization

     Executinτá thσá X25.CO═ transien⌠ commanΣ shoulΣá causσá thσ ì
prograφá t∩ bσ loadeΣ froφ disk¼á sigε on¼á anΣ displa∙ thσá maiε ì
menu shown in Figure 3-1.

     A⌠ thi≤ point¼á thσ X2╡ systeφ i≤ read∙ fo≥ operatioε and/o≥ ì
initialization of the default parameters.


------------------------------------------------------------------

X.25 packet communications program (06/28/84)
(c⌐ 198┤ EΣ Elizond∩ - al∞ right≤ reserved

X.25 main menu:

normal operation:              diagnostics:
    1. initialize link                10. display system parameters
    2. transmit restart packet        11. display status flags
    3. transmit file                  12. display L1 and L2 statistics
    4. abort file transmission        13. display L3 statistics
    5. receive file                   14. set flow control ready flags
    6. abort file reception           15. transmit bad frame
    7. transmit clear req. packet    16. change frame sequence
    8. query link status              17. start frame logging
    9. disconnect link                18. stop  frame logging

miscellaneous:
   19. change default parameters    21. exit to monitor
   20. change remote DTE address    22. exit to CP/M

option (cr to exit)=


------------------------------------------------------------------

                  Figure 3-1 - System Main Menu
.paè3.1  Initialization of System Default Parameters

     A⌠áá systeφá startup¼áá al∞á communicatioεá parameter≤áá arσ ì
initializeΣá t∩á thei≥ defaul⌠ values«á  Thσ defaul⌠á value≤á arσ ì
obtaineΣ froφ thσ disδ filσ X25.PAR¼á iµ sucΦ ß filσá exists¼á o≥ ì
froφá thσá option≤á selecteΣ a⌠ assembl∙ time¼á iµ n∩á sucΦá filσ ì
exists« T∩ initializσ thσ defaul⌠ value≤ anΣ generatσ thσ X25.PA╥ ì
filσá fo≥á ß giveε installation¼á selec⌠ optioε ú 1╣ a⌠ thσá maiε ì
men⌡á prompt«á  Thσ systeφ wil∞ theε promp⌠ thσ operato≥ fo≥á thσ ì
desireΣ communicatioε parameter≤ a≤ follows:



baud rates:

1.   300 baud
2.   600 baud
3.  1200 baud
4.  2400 baud
5.  4800 baud
6.  9600 baud
7. 19200 baud

option (cr to exit)= 3

     Ente≥áá thσá desireΣá bauΣá ratσá optioεá desireΣá fo≥áá thσ ì
particula≥á installation«á  Notσ tha⌠ thσ maximuφ erro≥ freσ ratσ ì
ma∙ var∙ witΦ particula≥ installations«á  I⌠ i≤ recommendeΣá tha⌠ ì
thσá lowes⌠ ratσ (optioε 1⌐ bσ useΣ unti∞ thσ maximuφá error-freσ ì
ratσ supporteΣ b∙ thσ systeφ ha≤ beeε determined«

     Notσ tha⌠ thi≤ optioε i≤ onl∙ meaningfu∞ iµ thσ "Biτá Boardó ì
systeφá i≤á supplyinτ thσ clocδ t∩ thσ externa∞ devicσ (refe≥á t∩ ì
Sectioε 2.2)«  Iµ thσ externa∞ devicσ i≤ supplyinτ thσ clock¼ an∙ ì
optioε ma∙ bσ selecteΣ sincσ i⌠ wil∞ havσ n∩ effect«á  ┴ carriagσ ì
returεáá wil∞á leavσá thσá optioεá unchangeΣá froφá thσá previou≤ ì
selection«



level 2 mode:

1. DTE (normal mode)
2. DCE (test mode)
3. self-test mode (with loopback connector)

option (cr to exit)= 1


     Thi≤á optioεá determine≤ thσ assignmen⌠ oµá framσá addresse≤ ì
useΣá fo≥ linδ leve∞ commanΣ anΣ responsσ frames¼á iεá accordancσ ì
witΦ thσ X.2╡ standard«

     Fo≥á norma∞á operatioεá optioε ▒ (DTE⌐ shoulΣá bσá selected«  ì
Optioεá ▓ i≤ fo≥ usσ wheε tw∩ simila≥ DT┼ unit≤ mus⌠á communicatσ ìèwithou⌠á thσ intermediar∙ oµ ß networδ DC┼ (fo≥ examplσ wheεá tw∩ ì
"Biτá Boardóá system≤á arσ connecteΣ togethe≥á fo≥á debugginτá oµ ì
softwarσá modifications«á  Optioεá │á i≤ fo≥ usσá onl∙á iεá debuτ ì
operation≤á usinτá ß singlσ DT┼ systeφ iε ßá loopbacδá connectioε ì
arrangemen⌠á wherσ transmitteΣ datß i≤ feΣ bacδ t∩á thσá receiveΣ ì
datß terminal«  ┴ carriagσ returε wil∞ leavσ thσ optioε unchangeΣ ì
from the previous selection.



level 3 mode:

1. Virtual Call circuit (VC)
2. Permanent Virtual Circuit (PVC)

option (cr to exit)= 1


     Thi≤áá optioεáá determine≤áá whethe≥áá thσáá packe⌠ááá leve∞ ì
communication≤á modσ wil∞ corresponΣ t∩ thσ Virtua∞ Cal∞ (VC⌐á o≥ ì
Permanen⌠á Virtua∞ Circui⌠ (PVC⌐ servicσ clas≤ oµá operation¼á a≤ ì
defineΣ iε thσ X.2╡ standard«á  Iε simplifieΣ terms¼á thσ V├ modσ ì
require≤á cal∞á setu≡ packet≤ beforσ datß caε bσ transferreΣá anΣ ì
cal∞ clearinτ packet≤ afte≥ datß transmissioε i≤ complete¼á whilσ ì
PV├á circuit≤ caε transfe≥ datß packet≤ a⌠ an∙ time«á  Mos⌠á maiε ì
framσáá implementation≤á suppor⌠á onl∙á V├á (optioεá 1⌐á modσá oµ ì
operation«á ┴á carriagσ returε wil∞ leavσ thi≤á optioεá unchangeΣ ì
froφ thσ las⌠ selection«



local DTE address (0-15 hex digits) =

     Thi≤ optioε determine≤ thσ loca∞ DT┼ addres≤ oµ thσá system«  ì
Aεá addres≤á ma∙á bσ entereΣ b∙ typinτ froφ ░ t∩á 1╡á he°á digit≤ ì
(withou⌠ an∙ interveninτ spaces)« Iµ aε addres≤ i≤ selected¼ onl∙ ì
cal∞á reques⌠ packet≤ havinτ sucΦ aε addres≤ wil∞ bσ accepteΣá b∙ ì
thσ system«á  ┴ carriagσ returε wil∞ se⌠ thσ addres≤ lengtΦ t∩ 0«  ì



remote DTE address (0-15 hex digits) = 

     Thi≤ optioε determine≤ thσ initia∞ DT┼ addres≤ oµ thσ remotσ ì
systeφ beinτ accessed«á  A≤ before¼á aε addres≤ ma∙ bσ entereΣ b∙ ì
typinτá froφ ░ t∩ 1╡ he° digit≤ (withou⌠ an∙ interveninτ spaces)« ì
Iµ aε addres≤ i≤ selected¼á thσ addres≤ wil∞ bσ incorporateΣ int∩ ì
al∞á cal∞á reques⌠ packet≤ sen⌠ b∙ thσ system«á  Notσá tha⌠á somσ ì
main-framσá implementation≤á accep⌠ onl∙ ┤ he° digit≤ fo≥á ßá DT┼ ì
addres≤á anΣ tha⌠ thi≤ addres≤ i≤ useΣ t∩ selec⌠ thσá destinatioε ì
proces≤ oµ thσ packe⌠ communications«  Notσ als∩ tha⌠ optioε ú 2░ ì
oµá thσ maiε men⌡ caε bσ useΣ t∩ changσ thi≤ addres≤ a⌠ an∙ time«  ì
Usinτá optioεá ú 1╣ select≤ thσ initia∞ defaul⌠á valuσá fo≥á thi≤ ì
address¼ whicΦ remain≤ unchangeΣ wheε optioε ú 2░ i≤ selected«
è
     Afte≥ selectioε oµ thσ abovσ option¼ ß ne≈ defaul⌠ paramete≥ ì
filσá X25.PA╥ i≤ generateΣ oε thσ currentl∙ loggeΣ disk¼á anΣ thσ ì
systeφ i≤ read∙ fo≥ operation«á   Thσ selecteΣ parameter≤ ma∙á bσ ì
verifieΣ b∙ mean≤ oµ maiε men⌡ optioε ú 10.



4.  Using the System

     Assuminτá tha⌠ thσ systeφ i≤ connecteΣ t∩ aε activσá networδ ì
por⌠ anΣ tha⌠ thσ systeφ defaul⌠ parameter≤ havσ beeε initializeΣ ì
a≤ describeΣ iε Sectioε 3.1¼ t∩ usσ thσ systeφ iε packe⌠ termina∞
modσá require≤á simpl∙ tha⌠ thσ linδ connectioεá bσá established«  ì
Oncσ thσ linδ connectioε i≤ established¼á establishinτ thσ packe⌠ ì
leve∞á cal∞á occur≤á automaticall∙á wheεá thσá firs⌠á messagσá i≤ ì
transmitted«á  Thσá followinτ section≤ describσ iε greate≥ detai∞ ì
thσ operatioε oµ thσ systeφ anΣ variou≤ option≤ availablσá durinτ ì
norma∞á operation«á  ┴ summar∙ oµ thσ option≤ availablσ froφá thσ ì
main menu is included in Appendix I.



4.1  Special Command Characters

     Wheεá thσá systeφ i≤ iε control¼á thσ followinτá characters¼ ì
wheεá typeΣá locall∙ a⌠ thσ systeφ console¼á arσá interpreteΣá a≤ ì
specia∞ commands:


escapeáááááááá- thi≤á characte≥á make≤ thσ systeφ returεá t∩á thσ ì
áááááááááááááámaiε   menu.


control-B áááá- thi≤ characte≥ command≤ thσ systeφ t∩ transmi⌠ aε ì
ááááááááááááááinterrup⌠ packet« Thσ interrup⌠ packe⌠ wil∞ onl∙ bσ ì
áááááááááááááátransmitteΣá iµ thσ packe⌠ channe∞ i≤ iεá thσá flo≈ ì
áááááááááááááácontro∞á read∙á statσá (p▒ o≥ d1⌐ anΣ iµá n∩á othe≥ ì
ááááááááááááááinterrupt≤ arσ pendinτ confirmation¼á otherwisσá aε ì
ááááááááááááááerro≥ messagσ results«


control-Pá ááá- thi≤á commanΣ turn≤ thσ harΣ cop∙ printe≥ oεá anΣ ì
ááááááááááááááoff¼á simila≥á t∩ thσ samσ functioε iεá CP/M«á  Thσ ì
ááááááááááááááconsolσ bell¼á iµ installed¼ i≤ soundeΣ t∩ indicatσ ì
ááááááááááááááwheεá thσ printe≥ i≤ turneΣ oε iε ß manne≥á simila≥ ì
áááááááááááááát∩ CP/═ 3.0.


control-Uá ááá- thi≤á commanΣ delete≤ thσ las⌠ (incomplete⌐ typeΣ ì
ááááááááááááááline¼ simila≥ t∩ thσ samσ functioε iε CP/M«


deleteé        - thi≤ commanΣ delete≤ thσ las⌠ typeΣ character.
è.cp3

carriagσ
     return áá- thi≤á commanΣ transmit≤ thσ previousl∙ typeΣ linσ ì
ááááááááááááááa≤á ßá datßá packet¼á provideΣ thσá linδá ha≤á beeε ì
ááááááááááááááinitializeΣ anΣ thσ packe⌠ channe∞ i≤ iε thσá read∙ ì
áááááááááááááá(r1⌐  o≥ flo≈ contro∞ read∙ (p▒ o≥ d1⌐ state.



4.2  Connecting the Link

     Thσá firs⌠ ste≡ afte≥ initializinτ thσ defaul⌠ parameter≤ i≤ ì
t∩á establisΦá thσá linδá leve∞á connection«áá  Thσá linδáá leve∞ ì
connectioεá ma∙ bσ originateΣ eithe≥ locall∙ b∙ thσ DT┼á (system⌐ ì
o≥ remotely b∙ thσ DCE (network)«

     Assuminτá tha⌠á thσá systeφ seria∞á communication≤á por⌠á i≤ ì
connecteΣ t∩ aε activσ networδ port¼á thσ systeφ a⌠ thi≤ poin⌠ i≤ ì
transmittinτá continuou≤ flag≤ t∩ thσ networδ anΣ hopefull∙á als∩ ì
receivinτ flag≤ froφ thσ network«

     Iµá i⌠á i≤ desireΣ t∩ originatσ thσ linδ connectioεá (o≥á t∩ ì
rese⌠ aε existinτ connection⌐ a⌠ thσ DTE¼ simpl∙ selec⌠ maiε men⌡ ì
optioεá #▒á (initializσá link)«á  Thi≤ wil∞ causσ thσá systeφá t∩ ì
transmi⌠á ß SAB═ framσ t∩ thσ network«á  Aε activσá networδá wil∞ ì
repl∙ witΦ ß U┴ frame¼ a⌠ whicΦ poin⌠ thσ linδ i≤ establisheΣ anΣ ì
thσá messagσá "L2║á r°á U┴ - linδ connectedó wil∞ appea≥á oεá thσ ì
system console.

     Iµá n∩ U┴ framσ i≤ receiveΣ froφ thσ DC┼ withiε 1░á seconds¼ ì
thσá SAB═ framσ i≤ retransmitted«á  Thi≤ proces≤ i≤á repeateΣá 1░ ì
times¼ a⌠ whicΦ point¼ iµ n∩ repl∙ ha≤ beeε received¼ thσ networδ ì
i≤á declareΣá non-operatinτ anΣ thσ messagσ "L2║á t° retr∙á coun⌠ ì
exhausted - no reply from dce" will appear on the system console.

     Iµ desired¼á thσ systeφ ma∙ awai⌠ initializatioε oµ thσ linδ ì
b∙á thσá DC┼ (network)«á  Thi≤ i≤ accomplisheΣá b∙á selectinτá n∩ ì
optioεá (b∙ typinτ ß carriagσ return⌐ a⌠ thσ maiε menu«á Iεá thi≤ ì
mode¼á thσá systeφ wil∞ awai⌠ receptioε oµ ß SAB═ framσ froφá thσ ì
DC┼á and¼á wheε sucΦ ß framσ i≤ received¼á thσ systeφ wil∞á repl∙ ì
witΦá ß U┴ frame¼á causinτ thσ linδ connectioε t∩ bσ established«  ì
Thi≤á wil∞ bσ indicateΣ t∩ thσ operato≥ b∙ thσá messagσá "L2║á r° ì
SABM - link connected by dce" appearing on the system console.

     Notσ tha⌠ beforσ thσ SAB═ framσ i≤ received¼ thσ systeφ wil∞ ì
repl∙á witΦá ß disconnec⌠ modσ (DM⌐ framσ t∩ an∙ receiveΣá frame≤ ì
havinτ thσ pol∞ bi⌠ ╜ 1«  Aε activσ networδ wil∞ repl∙ t∩ thi≤ D═ ì
framσ b∙ transmittinτ ß SAB═ frame¼á thu≤ establishinτ thσá link«  ì
A⌠á typica∞á main-framσá implementations¼á wheεá n∩á activit∙á i≤ ì
detecteΣá afte≥ ß perioΣ oµ time¼á thσ networδ por⌠á periodicall∙ ì
transmit≤ R╥ frame≤ witΦ thσ pol∞ bi⌠ se⌠ t∩ 1«á  Wheε thσ systeφ ì
i≤á connecteΣ t∩ sucΦ ß port¼á thi≤ wil∞ causσ thσá RR-DM-SABM-U┴ ì
handshakσá t∩á occur¼á thu≤ automaticall∙ establishinτá thσá linδ ì
connection.
è     Thσá statσ oµ thσ linδ connectioε ma∙ bσ determineΣá a⌠á an∙ ì
timσá b∙á selectinτá optioε ú ╕ (quer∙ linδ status⌐ a⌠á thσá maiε ì
systeφ menu«  Iµ thσ linδ i≤ connecteΣ anΣ botΦ end≤ arσ read∙ t∩ ì
accep⌠ transmitteΣ frames¼á thσ message≤ "L2║ dtσ readyó anΣ "L2║ ì
dcσ readyó wil∞ appea≥ oε thσ systeφ console.



4.3  Remote DTE Address Selection

     Thσá currentl∙ selecteΣ remotσ DT┼ addres≤ ma∙ bσá displayeΣ ì
b∙ mean≤ oµ optioε ú 1░ oµ thσ systeφ maiε menu«á  T∩ changσá thσ ì
remotσ DTE address¼ fo≥ examplσ t∩ acces≤ ß differen⌠ destinatioε ì
proces≤ througΦ thσ network, option # 20 may be selected.

     Wheεá optioε ú 2░ i≤ selected¼á ß ne≈ remotσ DT┼ addres≤ ma∙ ì
bσá entereΣá b∙á typinτá froφ ░ t∩ 1╡á he°á digit≤á (withou⌠á an∙ ì
interveninτá spaces)«á  ┴á carriagσ returε wil∞ se⌠á thσá addres≤ ì
lengtΦ t∩ 0«  Aε invaliΣ addres≤ wil∞ repea⌠ thσ promp⌠ fo≥ ß ne≈ ì
address.

     Thσá addres≤ s∩ selecteΣ wil∞ bσ incorporateΣ int∩ an∙á cal∞ ì
reques⌠ packet≤ transmitteΣ b∙ thσ systeφ unti∞ modifieΣ agaiε b∙ ì
mean≤á oµ optioε ú 2░ (o≥ reinitializinτ thσ systeφá parameters)«  ì
Notσá tha⌠á selectioε oµ aε addres≤ b∙ mean≤ oµ optioε ú 2░á doe≤ ì
no⌠ changσ thσ defaul⌠ addres≤ initializeΣ a⌠ systeφ startup«  T∩ ì
changσ thσ initia∞ addres≤ selectioε yo⌡ mus⌠ usσ optioε ú 1╣á t∩ ì
change the default parameters.



4.4  Packet Level Initialization

     Iµ thσ linδ i≤ establisheΣ b∙ thσ DT┼ (system)¼á thσá systeφ ì
automaticall∙á transmit≤ ß RESTAR╘ REQUES╘ packe⌠ t∩ thσ network«  ì
Aε activσ networδ wil∞ repl∙ witΦ ß RESTAR╘ CONFIRMATIO╬á packet¼ ì
whicΦá indicate≤ tha⌠ thσ packe⌠ leve∞ i≤ iε thσ read∙ (p1⌐ stateì
awaitinτá ß cal∞ setup«á  Thi≤ wil∞ bσ indicateΣ b∙á thσá messagσ ì
"L3║á r° restartó displayeΣ oε thσ operato≥ console«á Iµ n∩ repl∙ ì
packe⌠ i≤ receiveΣ withiε 18░ seconds¼ thσ RESTAR╘ REQUES╘ packe⌠ ì
i≤ retransmitted«á  Iµ n∩ repl∙ i≤ receiveΣ thσ seconΣ time¼á thσ ì
networδá i≤ declareΣ ou⌠ oµ orde≥ anΣ thσ messagσ "L3║á t°á retr∙ ì
coun⌠ exhausteΣ - n∩ repl∙ froφ DCEó i≤ displayed.

     Iµ thσ linδ i≤ establisheΣ b∙ thσ networδ (DCE)¼á thσ systeφ ì
await≤ ß RESTAR╘ INDICATIO╬ packe⌠ froφ thσ networδ anΣ wheε sucΦ ì
ßá packe⌠á i≤á received¼á thσ systeφ wil∞á rel∙á witΦá ßá RESTAR╘ ì
CONFIRMATIO╬á packet¼á thu≤ causinτ thσ packe⌠ leve∞ t∩ ente≥ thσ ì
ready (p1) state and await a call setup.

     Iµ necessary¼ ß RESTAR╘ REQUES╘ packe⌠ caε bσ transmitteΣ b∙ ì
the system by use of option # 2 on the main menu.


è4.5  Establishing the Call

     Iµ thσ Permanen⌠ Virtua∞ Circui⌠ (PVC⌐ modσ oµ operatioε ha≤ ì
beeεá selecteΣ a⌠ systeφ initialization¼á anΣ iµ thσ DC┼ support≤ ì
thi≤á clas≤ oµ operation¼á n∩ cal∞ setu≡ i≤ necessar∙ anΣá packe⌠ ì
transmissioε anΣ receptioε ma∙ begiε a⌠ an∙ time« (notσ tha⌠ most ì
main-framσ implementation≤ d∩ no⌠ suppor⌠ PV├ modσ oµ operation).

     Iµá thσá Virtua∞á Cal∞á (VC⌐á modσá oµá operatioεá ha≤á beeε ì
selected¼ ß packe⌠ leve∞ cal∞ mus⌠ bσ establisheΣ beforσ an∙ datß ì
packet≤á ma∙á bσ transmitteΣ o≥á received«á  Establishmen⌠á oµá ß ì
packe⌠á leve∞á cal∞ i≤ automaticall∙ accomplisheΣ b∙á thσá systeφ ì
when the first console data packet is transmitted.

     T∩á establisΦ thσ packe⌠ leve∞ call¼á i⌠ i≤ merel∙ necessar∙ ì
t∩ transmi⌠ ß datß packet«á  Thi≤ i≤ mos⌠ easil∙ donσ b∙ typinτ ß ì
carriagσ returε a⌠ thσ systeφ console«á  Thσ systeφ automaticall∙ ì
transmit≤á ßá CAL╠á REQUES╘á packe⌠á containinτá thσáá previousl∙ ì
selecteΣá DT┼á addresses«á  Aε activσ networδ iε thσá read∙á (p1⌐ ì
statσá wil∞ repl∙ witΦ ß CAL╠ ACCEPTE─ packet¼á iµ i⌠ caεá accep⌠ ì
thσ call¼á o≥ ß CAL╠ REJECTE─ packe⌠ iµ i⌠ cannot«á  Thi≤ wil∞ bσ ì
indicateΣá b∙ thσ messagσ "L3║á r° cal∞ connectedó o≥á "L3║á cal∞ ì
refuseΣ - t° clea≥ requestó displayeΣ a⌠ thσ systeφ console«á  A≤ ì
indicateΣá iεá thσá latte≥ message¼á ß rejecteΣ cal∞á cause≤á thσ ì
system to transmit a CLEAR REQUEST packet in confirmation.

     Wheε thσ CAL╠ ACCEPTE─ packe⌠ i≤ receiveΣ b∙ thσ system¼ thσ ì
channe∞á i≤ theε placeΣ iε thσ flo≈ contro∞ read∙ (d1⌐ statσá anΣ ì
thσ systeφ proceed≤ t∩ transmi⌠ thσ outstandinτ datßá packet¼á iε ì
this case, a packet containing a carriage return-line feed pair.

     Thσ cal∞ setu≡ ma∙ bσ originateΣ b∙ thσ DCE«á  Iε thi≤ case¼ ì
thσá systeφá receive≤ aε INCOMIN╟ CAL╠ packet¼á indicateΣ b∙á thσ ì
messagσ "L3║á r° incominτ calló displayeΣ a⌠ thσ systeφá console«  ì
Thσ systeφ verifie≤ tha⌠ thσ incominτ cal∞ packe⌠ ha≤ thσ correc⌠ ì
loca∞á DT┼á addres≤á and¼á iµ so¼á replie≤ witΦ ßá CAL╠á ACCEPTE─ ì
packet¼á a⌠ whicΦ poin⌠ thσ systeφ enter≤ thσ flo≈ contro∞á read∙ ì
(d1) state.

     Iµá thσá incominτ cal∞ packe⌠ ha≤ aεá invaliΣá address¼á thσ ì
systeφá replie≤á witΦ ß CLEA╥ REQUES╘ packet¼á indicateΣá b∙á thσ ì
messagσá "L3║á baΣ addres≤ - t° clea≥ request"«á  Thσ systeφ theε ì
awaits another call.



4.6  Operation in Packet Terminal Mode


     Afte≥á thσ packe⌠ cal∞ i≤ establisheΣ anΣ thσ systeφá i≤á iε ì
thσá flo≈á contro∞ read∙ (d1⌐ state¼á an∙ message≤ typeΣá a⌠á thσ ì
systeφá consolσá arσ transmitteΣ a≤ datß packets¼á a≤ sooεá a≤á ß ì
carriagσ returε i≤ typed«

     Notσá tha⌠ thσ systeφ automaticall∙ add≤ ß linσá feeΣá afte≥ ìèeacΦá carriagσá returε tha⌠ i≤ typed«á  Notσ als∩ tha⌠ sincσá thσ ì
maximuφá packe⌠á sizσ handleΣ b∙ thσ systeφ i≤á 12╕á datßá bytes¼ ì
longe≥á message≤á typeΣ a⌠ thσ systeφ consolσ wil∞ bσá brokeεá u≡ ì
int∩á morσá thaεá onσá packe⌠ (thσ maximuφá consolσá buffe≥á sizσ ì
currentl∙ implementeΣ iε thσ systeφ i≤ 25╢ bytes¼ longe≥ message≤ ì
thaε thi≤ wil∞ bσ truncateΣ t∩ 25╢ bytes.⌐

     Thσ systeφ prompt≤ thσ operato≥ witΦ ß '>>º wheε i⌠ i≤ read∙ ì
to accept the next message for transmission.

     Thσá content≤ oµ an∙ datß packet≤ receiveΣ afte≥ thσá packe⌠ ì
cal∞á i≤á establisheΣá arσá displayeΣá unchangeΣá a⌠á thσá systeφ ì
console¼á excep⌠á tha⌠á al∞á contro∞ character≤á othe≥á thaεá thσ ì
following are replaced by a period ('.'):
ì


                    carriage return
                    line feed
                    form feed
                    bell
                    horizontal tab
                    back space



4.7  Transmitting Interrupt Packets

     Oncσá thσ packe⌠ cal∞ ha≤ beeε establisheΣ a≤á describeΣá iε ì
Sectioε 4.5¼á INTERRUP╘ packet≤ ma∙ bσ transmitteΣ a⌠ an∙ timσ b∙ ì
typinτá control-┬á (break⌐ a⌠ thσ systeφ console«á  Thσ DC┼á wil∞ ì
repl∙á t∩á thi≤ interrup⌠ packe⌠ witΦ aεá INTERRUP╘á CONFIRMATIO╬ ì
packe⌠á anΣá takσ whateve≥ loca∞ actioε ha≤á beeεá programmeΣá iε ì
responsσá t∩ interrupt≤ (thi≤ i≤ ß networδ option)«á  Receip⌠á oµ ì
thσá interrup⌠á confirmatioεá wil∞á bσ indicateΣá a⌠á thσá systeφ ì
consolσ b∙ thσ messagσ "L3║ r° interrup⌠ confirmatioε packet".

     Onl∙áá onσá INTERRUP╘á packe⌠á ma∙á bσáá transmitteΣáá unti∞ ì
confirmed«á  Attemp⌠á b∙ thσ operato≥ t∩ senΣ ß seconΣá INTERRUP╘ ì
packe⌠á beforσ thσ INTERRUP╘ CONFIRMATIO╬ packe⌠ ha≤ beσ receiveΣ ì
wil∞ resul⌠ iε aε erro≥ message.



4.8  Transmitting File Data

     Beforσ transmittinτ an∙ filσ data¼á thσ packe⌠ cal∞ mus⌠á bσ ì
establisheΣá a≤á describeΣá iε Sectioεá 4.5«á Oncσá thσá cal∞á i≤ ì
established¼á filσá datßá ma∙á bσá transmitteΣá a⌠á an∙á timσá b∙ ì
selectinτ maiε men⌡ optioε ú 3«

     Wheεá optioε ú │ i≤ selecteΣ a⌠ thσ maiεá menu¼á thσá systeφ ì
wil∞á asδ fo≥ ß filσ name¼á provideΣ ß filσ transmissioεá i≤á no⌠ ì
alread∙ iε process«á  Typinτ ß carriagσ returε a⌠ thi≤ poin⌠ wil∞ ì
abor⌠ thσ filσ transmissioε request«  Typinτ aε invaliΣ filσ namσ ìèwil∞á causσ thσ filσ namσ questioε t∩ bσ repeated«á ┴ valiΣá filσ ì
namσ ma∙ contaiε onl∙ alphanumeriπ character≤ anΣ ma∙ contaiεá aε ì
optiona∞á drivσá namσá anΣ filσá typσá specifier¼á followinτá thσ ì
standarΣ CP/═ convention¼ fo≥ examplσ B:test.dat.

     Oncσ ß valiΣ filσ namσ ha≤ beeε entered¼á thσ systeφá check≤ ì
t∩á seσá iµ thσ filσ exist≤ oε thσ specifieΣ disk«á  Iµ thσá filσ ì
doe≤ no⌠ exist¼á thσ filσ transmissioε reques⌠ i≤ aborteΣ anΣ thσ ì
message "L4: file not found" is displayed.

     Iµá thσá filσ exists¼á transmissioε oµ thσá filσá datßá wil∞ ì
proceeΣ automaticall∙ unti∞ thσ enΣ oµ filσ unles≤ aborted«  Filσ ì
transmissioεá ma∙ bσ aborteΣ a⌠ an∙ timσ b∙ selectinτ optioε úá ┤ ì
a⌠ thσ maiε menu«

     Durinτ filσ transmission¼á an∙ message≤ typeΣ a⌠ thσ consolσ ì
wil∞á no⌠á bσá transmitteΣá t∩á thσá DC┼á unti∞á afte≥á thσá filσ ì
transmissioε i≤ complete«á  Notσ tha⌠ thσ maximuφ consolσ messagσ ì
sizσ oµ 25╢ byte≤ applie≤ als∩ iε thi≤ case«



4.9  Receiving File Data

     Beforσá receivinτ filσ data¼á thσ packe⌠ leve∞ cal∞ mus⌠á bσ ì
establisheΣá a≤á describeΣá iε sectioε 4.5«á  Oncσ thσá  cal∞á i≤ ì
established¼á filσ datß ma∙ bσ receiveΣ a⌠ an∙ timσ b∙á selectinτ ì
option # 5 from the main menu.

     Wheεá optioεá ú ╡ i≤ selecteΣ a⌠ thσ maiε menu¼á thσá systeφ ì
ask≤ fo≥ ß filσ name¼ provideΣ filσ datß receptioε i≤ no⌠ alread∙ ì
iεá process«á  Typinτ ß carriagσ returε a⌠ thi≤ poin⌠ wil∞á abor⌠ ì
thσá filσ receptioε request«á  Typinτ aε invaliΣ filσá namσá wil∞ ì
causσ thσ filσ namσ questioε t∩ bσ repeated«  Again¼ ß valiΣ filσ ì
namσá ma∙ contaiε onl∙ alphanumeriπ characters¼á witΦ aε optiona∞ ì
filσá typσ anΣ disδ drivσ specifie≥ iε accordancσá witΦá standarΣ ì
CP/M convention.

     Oncσá ß valiΣ filσ namσ ha≤ beeε entered¼á thσ systeφ check≤ ì
fo≥á thσá existencσ oµ ß filσ b∙ thσ samσ namσ oεá thσá specifieΣ ì
disk«á Iµá sucΦ ß filσ i≤ found¼á thσ systeφ ask≤á "filσá alread∙ ì
exists¼ deletσ i⌠ (y/n)?"«  Answerinτ anythinτ othe≥ thaε "yó (o≥ ì
"Y"⌐á wil∞ abor⌠ thσ filσ receptioε request«á  Answerinτ "yóá (o≥ ì
"Y") will erase the previous file of the same name.

     Oncσá thσá receivσ filσ ha≤ beeεá successfull∙á opened¼á al∞ ì
receiveΣá datßá wil∞á bσ writteε ont∩ thi≤ filσá unti∞á thσá filσ ì
receptioεá modσá i≤ aborteΣ b∙ mean≤ oµ optioε ú ╢ froφ thσá maiε ì
menu«

     Durinτá filσ datß receptioε ß plu≤ sigε '+º i≤ displayeΣá oε ì
thσá screeεá a≤ ß progres≤ signa∞ fo≥ ever∙ datß packe⌠á receiveΣ ì
anΣ writteε t∩ thσ file«  Thσ receiveΣ datß i≤ unchangeΣ a≤ i⌠ i≤ ì
writteε t∩ thσ file«
è

4.10  Terminating the Call

     Terminatinτ thσ packe⌠ leve∞ cal∞ ma∙ bσ donσ a⌠ an∙ timσ b∙ ì
selectinτá maiε men⌡ optioε ú 7«á  Iµ thσ linδ i≤ connecteΣá thi≤ ì
wil∞á resul⌠ iε thσ transmissioε oµ ß CLEA╥ REQUES╘ packet«á  Thσ ì
DC┼á wil∞á normall∙ repl∙ witΦ ß DC┼ CLEA╥á CONFIRMATIO╬á o≥á DC┼ ì
CLEA╥á INDICATIO╬á packet¼á a⌠ whicΦ poin⌠ thσ packe⌠ leve∞á wil∞ ì
closσá an∙ transmi⌠ o≥ receivσ file≤ tha⌠ ma∙ bσ opeεá anΣá ente≥ ì
thσ read∙ (p1⌐ statσ to awai⌠ anothe≥ call.

     Thσá cal∞ ma∙ als∩ bσ terminateΣ b∙ thσ DC┼ b∙á transmissioε ì
oµá ß CLEA╥ INDICATIO╬ packet«á  Wheε thi≤ packe⌠ i≤ receiveΣá a⌠ ì
thσá DTE¼á thi≤ wil∞ bσ indicateΣ a⌠ thσ consolσ b∙á thσá messagσ ì
"L3║á r°á clea≥ indicatioε packet¼á causσ ╜ xx"¼á wherσ x° i≤ thσ ì
causσ fo≥ thσ cal∞ termination«á  Thσ DT┼ wil∞ repl∙ witΦ ß CLEA╥ ì
CONFIRMATIO╬ packet¼ closσ an∙ transmi⌠ o≥ receivσ file≤ tha⌠ ma∙ ì
bσ opeε anΣ ente≥ thσ read∙ (p1⌐ statσ t∩ awai⌠ anothe≥ call«



4.11  Disconnecting the Link

     Thσá linδá connectioεá ma∙ bσ disconnecteΣ a⌠á an∙á timσá b∙ ì
selectinτ optioε ú ╣ froφ thσ maiε menu«á  Thi≤ optioε wil∞ causσ ì
thσá transmissioε oµ ß DIS├ frame«á  Aε activσ networδ wil∞ repl∙ ì
witΦá ßá U┴á frame¼á a⌠á whicΦ poin⌠á thσá framσá leve∞á linδá i≤ ì
disconnected«  Thi≤ wil∞ bσ indicateΣ a⌠ thσ systeφ consolσ b∙ tΦ ì
message "L2: rx UA - link disconnected'.

     Iµ n∩ repl∙ i≤ receiveΣ withiε 1░ second≤ thσ DIS├ framσá i≤ ì
retransmitted«á  Thi≤á proces≤á i≤ repeateΣ 1░á times¼á a⌠á whicΦ ì
point¼á iµá n∩ repl∙ ha≤ beeε received¼á thσ networδ i≤á declareΣ ì
non-operationa∞á anΣ thσ messagσ 'L2║á t° retr∙ coun⌠ exhausteΣ - ì
n∩ repl∙ froφ DCEó i≤ displayeΣ a⌠ thσ console.

     Thσ linδ ma∙ als∩ bσ disconnecteΣ b∙ thσ DC┼ b∙ transmissioε ì
oµá ß DIS├ frame«á  Wheε ß DIS├ framσ i≤ received¼á thi≤ wil∞á bσ ì
indicateΣ b∙ thσ messagσ "L2║ r° DIS├ - linδ disconnecteΣ b∙ dceó ì
a⌠ thσ systeφ console«á Thσ systeφ wil∞ repl∙ witΦ ß U┴ frame¼ a⌠ ì
which point the link will be disconnected.



5.  Diagnostic Facilities


5.1  Link Query Function

     Thσ linδ quer∙ function¼ requesteΣ b∙ optioε ú ╕ oµ thσ maiε ì
systeφá menu¼á provide≤á thσ curren⌠ linδ statu≤ a≤ perceiveΣá b∙ ì
both ends of the link.

     Wheεá thi≤ optioε i≤ selected¼á thσ systeφá interrogate≤á i⌠ ìèinterna∞á linδá statσ flags«á  Iµ thσ linδ i≤á disconnected¼á thσ ì
messagσ "L2║ dtσ linδ i≤ disconnectedó i≤ displayed«  Iµ thσ linδ ì
i≤ connected¼á thσ systeφ check≤ t∩ seσ iµ thσ DT┼ i≤ iε ßá framσ ì
reject¼á receivσá busy¼á o≥á receivσ read∙  conditioε anΣ iµá so¼ ì
display≤ thσ appropriatσ status«

     Thσá systeφ theε transmit≤ thσ appropriatσ RR¼á RN╥á o≥á RE╩ ì
frame¼á witΦ thσ pol∞ bi⌠ se⌠ t∩ 1¼á t∩ thσ DCE«  Thσ systeφ theε ì
await≤á ßá repl∙ framσ froφ thσ DC┼ witΦ thσ correspondinτá fina∞ ì
bi⌠á se⌠ t∩ 1«á  Wheε sucΦ ß framσ i≤ received¼á thσ systeφá theε ì
display≤ thσ correspondinτ DC┼ status«  Iε norma∞ conditions¼ thσ ì
messagσ displayeΣ wil∞ bσ "L2║á dcσ ready"¼á denotinτ tha⌠ aεá R╥ ì
frame with the final bit set to 1 has been received from the DCE.

     Iµá n∩ repl∙ framσ (witΦ thσ fina∞ bi⌠ se⌠ t∩ 1⌐ i≤ receiveΣ ì
withiεá 1░ seconds¼á thσ RR¼á RN╥ o≥ RE╩ framσá i≤á retransmitteΣ ì
(witΦá thσ pol∞ bi⌠ se⌠ t∩ 1)«á  Thi≤ proces≤ i≤ repeateΣ ß tota∞ ì
oµ 1░ times«á  Iµ n∩ repl∙ i≤ receiveΣ afte≥ thσ tentΦ time¼á thσ ì
link is automatically disconnected.



5.2  Diagnostic Display Screens

     Fou≥á diagnostiπá displa∙á screen≤á arσá availablσá t∩áá thσ ì
operato≥á iε responsσ t∩ maiε men⌡ option≤ ú 10¼á 11¼á 1▓ anΣ 13«  ì
┴ brieµ descriptioε oµ thσ informatioε availablσ oε thesσ screen≤ ì
i≤ a≤ follows║


System Parameters (option # 10)

     Thi≤á screeεá display≤á thσ curren⌠á statu≤á oµá al∞á systeφ ì
parameter≤ and flow control variables.


System Status Flags (option # 11)

     Thi≤ screeε display≤ thσ curren⌠ statσ oµ al∞ systeφ contro∞ ì
flags«á  Thσá definitioε oµ thesσ flag≤ ma∙ bσ founΣ iεá Appendi° ì
II«á  Iεá norma∞á packe⌠ termina∞ modσ oµá operation¼á afte≥á thσ ì
packe⌠á cal∞ ha≤ beeε established¼á thσ statσ oµ al∞ flag≤ shoulΣ ì
bσ ░ excep⌠ fo≥ leve∞ ▓ linδ statu≤ bi⌠ ú ▓ (linδ connected⌐á anΣ ì
level 3 channel status bit # 0 (flow control ready state d1).


L1 and L2 System Statistics (option # 12)

     Thi≤á screeεá display≤ thσ accumulateΣ total≤ oµ thσá systeφ ì
diagnostiπá counter≤á t∩ bσ displayeΣ fo≥ thσ leve∞á ▒á (hardwarσ ì
level) and level 2 (link level) functions.


L3 System Statistics (option # 13)
è     Thi≤á screeε display≤ thσ accumulateΣ total≤ oµá thσá systeφ ì
diagnostiπá counter≤á t∩á bσ displayeΣ fo≥ thσá leve∞á │á (packe⌠ ì
level) functions.



5.3  Special Debug Functions


     Asidσ froφ thσ linδ quer∙ functioε describeΣ iε Sectioε 5.1¼ ì
three specia∞ debuτ function≤ arσ availablσ t∩ thσ systeφ operato≥ ì
iεá responsσá t∩á maiεá men⌡ option≤ úá 14¼á 1╡á anΣá 16«á  Thesσ ì
functions¼á intendeΣ mainl∙ t∩ checδ ou⌠ specifiπ systeφ softwarσ ì
desigε areas¼ are:


Set Flow Control Ready Flags (option # 14)

     Thi≤á diagnostiπá functioε wil∞ causσ thσá loca∞á systeφá t∩ ì
behavσ a≤ iµ thσ leve∞ ▓ linδ haΣ beeε successfull∙ connecteΣ anΣ ì
thσ leve∞ │ linδ i≤ iε flo≈ contro∞ read∙ state«á  Thi≤á functioε ì
i≤á intendeΣá fo≥á usσ mainl∙ durinτ softwarσá checkou⌠á wheεá aε ì
activσ networδ i≤ no⌠ availablσ anΣ serve≤ n∩ usefu∞ purposσ wheε ì
thσ systeφ i≤ connecteΣ t∩ aε activσ network«


Transmit Bad Frame (option # 15)

     Thi≤á diagnostiπá functioεá wil∞ causσ ß transmissioεá oµá ß ì
framσ witΦ aε invaliΣ contro∞ fielΣ (0ffh)«á  Thi≤ wil∞ forcσ thσ ì
DC┼á t∩á repl∙á witΦ ßá CMD╥á (commanΣá reject⌐á response«á  Thi≤ ì
functioεá i≤á intendeΣá fo≥ usσ durinτ softwarσ checkou⌠á oµá thσ ì
systeφá exceptioεá condition≤á anΣ serve≤ n∩á purposσá iεá norma∞ ì
operation.


Change Frame Sequence (option # 16)


     Thi≤ diagnostiπ functioε wil∞ decremen⌠ (modσ 7⌐ thσ curren⌠ ì
valuσá oµ thσ framσ leve∞ senΣ statσ variablσá V(s)«á  Thi≤á wil∞ ì
causσá thσ DTE t∩ detec⌠ ß receiveΣ sequencσ erro≥ anΣ repl∙ witΦ ì
ß RE╩ (reject⌐ responsσ framσ bacδ t∩ thσ DTE«á  This¼á iεá turn¼ ì
shoulΣá causσ ß retransmissioε oµ thσ "missedó framσ b∙ thσá DTE« ì
Thi≤ functioε i≤ intendeΣ fo≥ softwarσ checkou⌠ oµ thi≤ exceptioε ì
condition and serves no useful purpose during normal operation.



5.4  Session Logging

     Thi≤á usefu∞ diagnostiπ functioε i≤ enableΣ anΣ disableΣá b∙ ì
maiε men⌡ option≤ ú 1╖ anΣ 1╕ respectively«

     Wheε thi≤ functioε i≤ enabled¼á al∞ transmitteΣ anΣ receiveΣ ìèframe≤á arσá loggeΣá iεá ßá specia∞á disδá filσá (X25.LOG)«á  Thσ ì
informatioε loggeΣ consist≤ oµ a⌐ thσ directioε oµá transmission¼ ì
b⌐á thσ framσ addres≤ fielΣ anΣ c⌐ thσ framσ contro∞á field«á  Aε ì
auxiliar∙á diagnostiπá prograφ (PLOG.COM⌐ ha≤ beeεá developeΣá t∩ ì
prin⌠á ou⌠á thi≤ informatioε iε tabula≥ forφ anΣ t∩ identif∙á thσ ì
addres≤ anΣ framσ typσ iε X.2╡ notation¼á a≤ wel∞ a≤ extrac⌠á thσ ì
sequencσáá number≤á N(s⌐á anΣá N(r)¼áá anΣá thσá poll/fina∞áá bi⌠ ì
informatioε froφ thσ contro∞ fielΣ oµ thσ frame.

     Notσ tha⌠ enablinτ thσ logginτ functioε b∙ mean≤ oµ optioε ú ì
1╖ erase≤ an∙ previousl∙ existinτ X25.LO╟ file«  Iµ i⌠ i≤ desireΣ ì
t∩ loτ morσ thaε onσ session¼á erasurσ oµ thσ earlie≥ sessioε loτ ì
ma∙á bσá preventeΣá b∙ renaminτ thσ existinτ X25.LO╟á filσá t∩á ß ì
differen⌠ namσ (fo≥ examplσ X25.L1).

     Sessioε logginτ ma∙ bσ starteΣ a⌠ an∙ time¼á eveε beforσ thσ ì
link connection has been established.




5.5  Assembly Time Debug Options

     Specia∞á assembl∙á timσ debuτ option≤ havσ beeε provideΣá iε ì
thσá module≤ X25.ASM¼á LEVEL2.AS═ anΣá LEVEL3.ASM«á  Thesσá debuτ ì
option≤ arσ enableΣ b∙ settinτ thσ modulσ loca∞ variablσá "debugó ì
equa∞á t∩ "trueó prio≥ t∩ assembl∙ time«á  Wheε thσ debuτ option≤ ì
are set to "true", the following functions are enabled:


X25.ASM debug option

     Settinτ thσ "debugó paramete≥ equa∞ t∩ "trueó iε thσ X25.AS═ ì
modulσ cause≤ al∞ receiveΣ consolσ datß packet≤ t∩ bσ taggeΣ witΦ ì
thσá symbo∞á <r╛ a⌠ thσ beginninτ oµ eacΦá packet«á  Thi≤á allow≤ ì
trackinτá oε thσ systeφ consolσ a≤ eacΦ packe⌠ i≤á receiveΣá wheε ì
lonτ tex⌠ message≤ arσ beinτ exchanged«


LEVEL2.ASM debug option

     Settinτá thσá "debugóá paramete≥á equa∞á t∩á "trueóá iεá thσ ì
LEVEL2.AS═ modulσ cause≤ thσ displa∙ a⌠ thσ systeφ consolσ oµ thσ ì
framσáá transmi⌠áá sequencσá numbe≥á N(s⌐á oµáá al∞áá transmitteΣ ì
informatioε frames«

     Iεá additioεá t∩á thσ above¼á thσ debuτá optioεá cause≤á thσ ì
entirσ content≤ oµ an∙ receiveΣ frame≤ havinτ ß baΣ addres≤ t∩ bσ ì
dumpeΣ (iε he° format⌐ oε thσ systeφ console«


LEVEL3.ASM debug option

     Settinτá thσá "debugóá paramete≥á equa∞á t∩á "trueóá iεá thσ ì
LEVEL3.AS═ modulσ cause≤ thσ displa∙ a⌠ thσ systeφ consolσ oµ thσ ìèpacke⌠ senΣ sequencσ numbe≥ P(s⌐ oµ al∞ transmitteΣ datß packets« ì
Iεá orde≥á t∩á distinguisΦ thσ packe⌠ sequencσ number≤á froφá thσ ì
framσá sequencσá number≤á displayeΣ b∙ thσ debuτá optioεá iεá thσ ì
LEVEL2.AS═á module¼á thσá packe⌠ sequencσ number≤á arσá displayeΣ ì
within square brackets [n].



5.6  Use of PFM Monitor

     Provision≤á havσá beeε includeΣ iε thσ systeφá t∩á exi⌠á thσ ì
systeφ t∩ thσ "Biτ Boardó PF═ monitor¼á leavinτ thσ systeφ statu≤ ì
unchanged«á  Thi≤á allow≤ examinatioε oµ memor∙ location≤á withiε ì
thσ system programs for diagnostic purposes.

     T∩á exi⌠ t∩ thσ PF═ monito≥ selec⌠ optioε ú 2▒ froφ thσ maiε ì
menu«á T∩ returε t∩ thσ systeφ prograφ withou⌠ reinitializinτ thσ ì
X2╡ system¼á typσ "G3ó a⌠ thσ PF═ monito≥ promp⌠ '*'«á  Thi≤ wil∞ ì
bypas≤ thσ initializatioε routine≤ anΣ returε contro∞ t∩ thσ maiε ì
prograφ loo≡ iε thσ system.

     Fo≥á ßá descriptioεá oµ thσ variou≤ command≤á anΣá function≤ ì
availablσá froφ thσ PF═ monito≥ refe≥ t∩ thσ PFM-8░ User≤á Manua∞ ì
supplied with the Digital Research Computer's "Big Board".



6. System Alteration


     Modification≤á t∩á thσ systeφ havσ beeε facilitateΣ  b∙á thσ ì
partitioninτá anΣ separatioε oµ thσ variou≤ X.2╡ protoco∞á level≤ ì
into seven independent relocatable modules as follows:


     1) X25.ASM     - the main sequencer and user interface
     2) LEVEL1.ASM  - the hardware/interrupt service module
     3) LEVEL2.ASM  - the link level (HDLC) handler
     4) LEVEL3.ASM  - the packet level handler
     5) BUFFERS.ASM - the data buffer handler
     6) FILES.ASM   - the disk file handler
     7) XUTIL.ASM   - miscellaneous utility functions


     Thσáá system¼áá a≤á implemented¼áá ma∙á bσá porteΣá t∩áá an∙ ì
microprocesso≥á systeφ havinτ thσ followinτ minimuφ hardwarσá anΣ ì
softwarσ requirements:


     Z80 processor, supporting Mode 2 interrupts
     Z80-SIO serial interface device
     Z80-CTC counter-timer device
     26K minimum of user available RAM
     CP/M (version 2.2 or later) operating system host
è
     WitΦá an∙á implementatioεá othe≥ thaε thσá origina∞á Digita∞ ì
ResearcΦ Computer'≤ "Biτ Boardó  change≤ wil∞ bσ requireΣ t∩á thσ ì
LEVEL▒áá module¼áá whicΦá contain≤á al∞á thσá hardwarσá dependen⌠ ì
subroutines«á N∩ change≤ shoulΣ bσ requireΣ t∩ thσ LEVEL2.AS═á o≥ ì
LEVEL3.AS═ o≥ BUFFERS.AS═ module≤ a≤ al∞ systeφ hardwarσ anΣ filσ ì
interfacinτ i≤ donσ viß CP/═ BDO╙ functions«  Change≤ t∩ thσ use≥ ì
interfacσá iε thσ X25.AS═ modulσ ma∙ bσ desirablσ fo≥á particula≥ ì
application≤á  (thσ curren⌠ x25.AS═ modulσ i≤ intendeΣ mostl∙á a≤ ì
an X.25 protocol debugging tool).


.paè.op




                           APPENDIX I


                SUMMARY OF SYSTEM USER FUNCTIONS

.paè.fo                         I-#
.pn1
     Thσ function≤ availablσ t∩ thσ systeφ operato≥ froφ thσ maiε ì
menu are as follows:


áááá0«á Standb∙ Stateé - Iµ n∩ optioε i≤ selecteΣ a⌠ thσá maiε ì
áááááááámenu¼ thσ systeφ return≤ t∩ thσ statσ existinτ beforσ thσ ì
áááááááámen⌡ displa∙ wa≤ requested«á  Iµ n∩ optioε i≤ selecteΣ a⌠ ì
áááááááásysteφá startup¼á thσá systeφ enter≤ ß standb∙ statσá anΣ ì
ááááááááawait≤á fo≥á establishmen⌠á oµ thσ linδá b∙á thσá networδ ì
áááááááá(DCE)«á  Typinτ aε escapσ characte≥ a⌠ thσ loca∞á consolσ ì
ááááááááreturn≤ thσ systeφ t∩ thσ maiε menu«


áááá1.á Initializσ Linké - Iµ thi≤ optioε i≤ selected¼á thσ systeφ ì
áááááááá(DTE⌐ wil∞ attemp⌠ t∩ establisΦ thσ linδ b∙á transmittinτ ì
ááááááááßá SAB═á (Se⌠á Asynchronou≤ BalanceΣ Mode⌐ framσá t∩á thσ ì
ááááááááremotσ DCE«á  Thσ linδ i≤ establisheΣ upoε thσá receptioε ì
ááááááááoµ ß valiΣ U┴ (UnnumbereΣ Acknowledgement⌐ framσ froφ thσ ì
ááááááááDCE«á  Iµá ßá valiΣá U┴ framσ i≤ no⌠ receiveΣá withiεá 1░ ì
ááááááááseconds¼á thσ systeφ retransmit≤ thσ SAB═ frame«á  Iµá n∩ ì
áááááááárepl∙ i≤ obtaineΣ afte≥ 1░ retries¼á thσ linδ i≤ declareΣ ì
ááááááááinoperativσá anΣ thσ systeφ return≤ t∩ thσ standb∙á statσ ì
áááááááát∩á awai⌠á connectioεá b∙á thσá DC┼á o≥á manua∞á operato≥ ì
ááááááááintervention.
áááááááá
ááááááááIµá thσá linδá i≤ successfull∙ establisheΣ b∙á thσá loca∞ ì
áááááááásysteφá (DTE)¼á thσ systeφ wil∞ theε transmi⌠á ßá RESTAR╘ ì
áááááááápacke⌠á anΣá awai⌠á thσá receptioεá oµá ßá valiΣá RESTAR╘ ì
ááááááááCONFIRMATIO╬á packe⌠á iε orde≥ t∩ initializσá thσá packe⌠ ì
ááááááááleve∞á t∩á thσá datßá transfe≥á state«á Iµá thσá linδá i≤ ì
ááááááááestablisheΣá b∙ thσ remotσ DCE¼á thσ systeφ wil∞ awai⌠á ß ì
ááááááááRESTAR╘ packe⌠ froφ thσ DCE.


áááá2.á transmi⌠ Restar⌠ Packeté  Wheε thi≤ functioε i≤á selected¼ ì
ááááááááthσá systeφá wil∞á transmi⌠á ßá restar⌠á reques⌠á packet¼ ì
ááááááááprovideΣ tha⌠ thσ leve∞ ▓ linδ i≤ connected«á  Thσ systeφ ì
ááááááááwill then enter the restart request state (r2).


áááá3.á Transmi⌠á Fileéá - Wheεá thi≤ functioεá i≤á selected¼á thσ ì
áááááááásysteφá wil∞ asδ fo≥ ß standarΣ CP/═ filσ namσ specifier«  ì
ááááááááThσá systeφá wil∞á theε checδ fo≥ thσá existencσá oµá thσ ì
ááááááááspecifieΣá file«á  Iµá thσ filσ exist≤ anΣá thσá linδá i≤ ì
ááááááááestablished¼á thσá systeφá wil∞ proceeΣ t∩á transmi⌠á thσ ì
ááááááááspecifieΣ datß filσ t∩ thσ hos⌠ iε thσ forφ oµ ß numbereΣ ì
áááááááásequencσá oµá datßá packets«á  Iµá thσ systeφá i≤á iεá V├ ì
áááááááá(Virtua∞á Call⌐  mode¼á thσ transmissioε oµ datßá packet≤ ì
ááááááááwil∞á bσá precedeΣ witΦ ß CAL╠ REQUES╘á packe⌠á anΣá wil∞ ì
ááááááááawai⌠á acceptancσá oµá thσá cal∞ a≤á indicateΣá witΦá thσ ì
ááááááááreceptioεá oµ ß valiΣ CAL╠ ACCEPTE─ packe⌠ froφ thσá DCE«  ì
ááááááááIµ thσ systeφ i≤ iε PV├ (Permanen⌠ Virtua∞ Circuit⌐ mode¼ ì
áááááááán∩á cal∞á setu≡ i≤ requireΣ anΣ thσá packe⌠á transmissioε ì
ááááááááwil∞ takσ placσ a≤ sooε a≤ thσ linδ leve∞ i≤ established«
è
áááá4.á Abor⌠á Filσá Transmissioné - Thi≤ functioε wil∞á sto≡á thσ ì
áááááááátransmissioεá oµá ßá datß filσá previousl∙á initiateΣá b∙ ì
ááááááááoptioε ▓  anΣ wil∞ closσ thσ datß file.


ááá 5.á Receivσ Fileé - Wheε thi≤ functioε i≤ selected¼ thσ systeφ ì
ááááááááwil∞ asδ fo≥ ß CP/═ filσ specifier«  Thσ systeφ wil∞ theε ì
ááááááááchecδá fo≥ thσ existencσ oµ ß filσ b∙ thσ samσ name«á  Iµ ì
áááááááásucΦá ßá filσ exists¼á thσ systeφ wil∞á asδá whethe≥á thσ ì
áááááááácurren⌠ filσ i≤ t∩ bσ deleted«á  Iµ thσ answe≥ i≤ 'Y'¼ o≥ ì
ááááááááiµá n∩ previou≤ filσ oµ thσ samσ namσ exists¼á thσ systeφ ì
ááááááááwil∞á opeε ß filσ witΦ thσ giveε name«á  Thσ systeφá wil∞ ì
áááááááátheεá monito≥á thσ networδ fo≥ an∙á valiΣá incominτá datß ì
áááááááápackets«  Wheε sucΦ ß packe⌠ i≤ received¼ thσ datß packe⌠ ì
ááááááááwil∞ bσ storeΣ oε thσ disδ filσ writσ buffer«á  Wheεá thσ ì
áááááááádisδ filσ buffe≥ i≤ full¼ thσ systeφ automaticall∙ write≤ ì
ááááááááthe buffer to the disk.

ááááááááFilσá receptioεá wil∞ continuσ unti∞ thσá filσá receptioε ì
áááááááámode is terminated by means of main menu option # 6.


áááá6.á Abor⌠á Filσá Receptionéá - Thi≤ functioεá wil∞á closσá thσ ì
ááááááááreceivσ datß filσ anΣ rever⌠ thσ systeφ t∩ termina∞ mode«  ì
ááááááááAn∙á datßá packet≤á remaininτá iεá thσá networδá wil∞á bσ ì
áááááááádisplayeΣ oε thσ systeφ console.


áááá7.á Transmi⌠áá Clea≥áá Reques⌠á Packetéá - Iµá thσáá linδáá i≤ ì
ááááááááestablished¼á thi≤ functioε wil∞ transmi⌠ ß clea≥ reques⌠ ì
áááááááápacket«á Thi≤á wil∞á havσ thσ effec⌠ oµá terminatinτá thσ ì
ááááááááVirtual Call in VC mode.


áááá8.á Quer∙á Linδá Statusé - Thi≤ functioε wil∞ firs⌠ displa∙á ß ì
áááááááámessagσá givinτá thσ linδ statu≤ oµ thσ loca∞á systeφá o≥ ì
ááááááááDTE« Iµ thσ linδ i≤ established¼ thσ systeφ wil∞ transmi⌠ ì
ááááááááßá suitablσ framσ witΦ thσ pol∞ bit=1¼á thu≤ forcinτá thσ ì
ááááááááremotσ DC┼ t∩ repl∙ witΦ ß statu≤ indicatioε frame«á  Thσ ì
ááááááááreceiveΣá DC┼á statu≤á indicatioεá i≤á displayeΣá t∩á thσ ì
ááááááááoperator«á Iµ n∩ repl∙ i≤ receiveΣ withiε 1░ seconds¼ thσ ì
ááááááááquer∙á framσ wil∞ bσ retransmitteΣ u≡ t∩ ß maximuφ oµá 1░ ì
áááááááátimes«á  Iµá n∩ repl∙ i≤ receiveΣ afte≥ 1░á retries¼á thσ ì
áááááááálinδá i≤á declareΣá inoperative«áá Thσá purposσá oµá thi≤ ì
ááááááááfunctioε i≤ mainl∙ diagnostic.


áááá9.á Disconnec⌠áá Linkéá -  Thi≤á functioεá wil∞áá attemp⌠áá t∩ ì
áááááááádisconnec⌠á thσ linδ b∙ transmittinτ ß DIS├á (Disconnect⌐ ì
ááááááááframe«á  Thσá linδá i≤ considereΣ disconnecteΣá upoεá thσ ì
ááááááááreceptioεá oµ ß valiΣ U┴ frame«á  Iµ ß valiΣ U┴ framσá i≤ ì
ááááááááno⌠á receiveΣ withiε 1░ seconds¼á thσ systeφá retransmit≤ ì
ááááááááthσá DIS├á frame«á  Iµá n∩á repl∙ i≤á obtaineΣá afte≥á 1░ ì
ááááááááretries¼á thσ linδ i≤ declareΣ inoperativσ anΣ thσ systeφ ìèááááááááreturn≤ t∩ thσ standb∙ statσ t∩ awai⌠ reconnectioε b∙ thσ ì
ááááááááDCE or manual operator intervention.


ááá10.á Displa∙ Systeφ Parametersé - Thi≤ diagnostiπ functioε wil∞ ì
áááááááácausσ thσ curren⌠ statσ oµ al∞ systeφ parameter≤ anΣ flo≈ ì
áááááááácontro∞ variable≤ t∩ bσ displayeΣ t∩ thσ operator.


ááá11.á Displa∙á Statu≤á Flagsé - Thi≤á diagnostiπá functioεá wil∞ ì
áááááááácausσ thσ curren⌠ statσ oµ al∞ systeφ contro∞ flag≤ t∩ bσ ì
áááááááádisplayeΣ t∩ thσ operator.


 áá12.  Displa∙á L▒ anΣ L▓ Statisticsé - Thi≤ diagnostiπá functioε ì
ááááááááwil∞áá causσá thσá accumulateΣá total≤á oµáá thσáá systeφ ì
áááááááádiagnostiπá counter≤á t∩á bσ displayeΣ fo≥á thσá Leve∞á ▒ ì
áááááááá(physica∞ level⌐ anΣ Leve∞ ▓ (linδ level⌐ functions.


áá 13«á Displa∙á L│ Statisticsé - Thi≤á diagnostiπá functioε ì
ááááááááwil∞áá causσáá thσá accumulateΣá total≤á oµá thσáá systeφ ì
áááááááádiagnostiπá counter≤á t∩á bσ displayeΣ fo≥á thσá Leve∞á │ ì
áááááááá(packet level) functions.


áá 14.  Se⌠á Flo≈ Contro∞  Read∙ Flagsé - Thi≤ diagnostiπ functioε ì
ááááááááwil∞á causσ thσ loca∞ systeφ t∩ behavσ a≤ iµ thσ Leve∞á ▓ ì
áááááááálinδ haΣ beeε successfull∙ connecteΣ anΣ thσ Leve∞ │ linδ ì
áááááááái≤ iε flo≈ contro∞ read∙ (d1⌐ state«á  Thi≤ functioεá wa≤ ì
áááááááámainl∙á useΣ durinτ thσ earl∙ desigε stage≤ t∩ facilitatσ ì
áááááááátesting.


ááá15.á Transmi⌠á BaΣ Frameé - Thi≤ diagnostiπ functioε wil∞ causσ ì
ááááááááthσ transmissioε oµ ß framσ witΦ aε invaliΣ contro∞ fielΣ ì
áááááááá(0ffh)«  Thi≤ functioε i≤ primaril∙ useΣ t∩ forcσ thσ DC┼ ì
áááááááát∩áá transmi⌠á ßá CMD╥á (commanΣá reject⌐á responsσáá fo≥ ì
áááááááádiagnostiπ purposes.


áá 16.  Changσ Framσ Sequenceé  Thi≤ diagnostiπ functioε wil∞
áááááááádecremen⌠á (moΣá 7⌐ thσ curren⌠ valuσ oµ thσá senΣá statσ ì
áááááááávariablσá V(s)«á  Thi≤ functioε i≤ intendeΣ t∩ causσá thσ ì
ááááááááDC┼á t∩á detec⌠ ß receiveΣ sequencσ erro≥ anΣá causσá thσ ì
áááááááátransmissioεá oµ ß RE╩ (reject⌐ responsσ bacδ t∩ thσá DT┼  ì
ááááááááin order to test this exception condition.


ááá17.á Star⌠á Framσá Loggingéá - Thi≤á diagnostiπá functioεá wil∞ ì
ááááááááenablσá logginτ oε ß specia∞ disδ filσ (X25.LOG⌐á oµá al∞ ì
ááááááááincominτ anΣ outgoinτ frames«á  A≤ presentl∙ implemented¼ ì
ááááááááthσáá logginτá informatioεá include≤á thσá directioεáá oµ ì
áááááááátransmission¼á thσá framσá addres≤á fielΣ anΣá thσá framσ ì
áááááááácontro∞áá field«áá  Aεáá auxiliar∙áá diagnostiπáá prograφ ìèáááááááá(PLOG.COM⌐áá ha≤áá beeεá developeΣá t∩á prin⌠áá ou⌠áá thσ ì
ááááááááinformatioεá iε tabula≥ forφ anΣ t∩ identif∙ thσá addres≤ ì
ááááááááanΣ packe⌠ typσ iε X.2╡ notation¼á a≤ wel∞ a≤ extrac⌠ thσ ì
áááááááásequencσá number≤á N(r⌐á anΣá N(s⌐á anΣá poll/fina∞áá bi⌠ ì
ááááááááinformatioε froφ thσ contro∞ fielΣ oµ thσ frame.


ááá18«á Sto≡á Framσ Loggingé - Thi≤ diagnostiπ functioε stop≤ ì
ááááááááthσ framσ logginτ functioε describeΣ abovσ anΣ close≤ thσ ì
áááááááálog file.


áá 19.  Changσ Defaul⌠ Parametersé - Thi≤ specia∞ functioε permit≤ ì
ááááááááthσá operato≥á t∩á changσ thσá followinτá systeφá defaul⌠ ì
ááááááááparameters:

áááááááá       baud rate (300-19200 baud in 7 steps)
áááááááá       level 2 mode (DTE, DCE or self test)
áááááááá       level 3 mode (PVC or VC)
áááááááá       local DTE address length
áááááááá       local DTE address
áááááááá       remote DTE address length
áááááááá       remote DTE address

ááááááááAfte≥á thσ abovσ parameter≤ arσ changed¼á thσ value≤á arσ ì
ááááááááwritteε iε ß specia∞ disδ filσ (X25.PAR)« Wheε thσ systeφ ì
áááááááái≤á starteΣ agaiε a⌠ ß futurσ session¼á thσá value≤á reaΣ ì
ááááááááfroφ thi≤ disδ filσ becomσ thσ defaul⌠ value≤ oε restart¼ ì
áááááááás∩á thσá parameter≤á remaiεá unchangeΣá froφá sessioεá t∩ ì
áááááááásessioε unles≤ changeΣ b∙ mean≤ oµ thi≤ option«


ááá20.  Changσá Remotσ DT┼ Addressé  Thi≤ functioε i≤ intendeΣá t∩ ì
ááááááááfacilitatσá changinτ thσ calleΣ (remote⌐ DT┼á addres≤á iε ì
áááááááácal∞á reques⌠ packet≤ t∩ allo≈ thσ systeφ t∩ bσ connecteΣ ì
áááááááát∩á variou≤á remotσ DTE'≤ o≥ processe≤ vißá thσá network«  ì
ááááááááUsinτá thi≤á functioεá doe≤ no⌠ changσá thσá defaul⌠á DT┼ ì
ááááááááaddres≤ useΣ a⌠ systeφ initialization.


ááá21. Exi⌠ t∩ Monitoré - Thi≤ diagnostiπ functioε wil∞ causσ thσ ì
áááááááásysteφá t∩ bσ terminateΣ anΣ contro∞ t∩ bσ passeΣ t∩á thσ ì
ááááááááPF═á monito≥ iε thσ Digita∞ ResearcΦá 'Biτá Board'«á  Thσ ì
ááááááááprimar∙á usσ oµ thi≤ functioε i≤ t∩ permi⌠ examinatioε oµ ì
áááááááámemor∙á location≤á withiεá thσá prograφá fo≥áá diagnostiπ ì
áááááááápurposes.


ááá22.á Exi⌠ t∩ CP/Mé - Thi≤ functioε wil∞ causσ al∞ opeε file≤ t∩ ì
áááááááábσ closed¼á t∩ terminatσ thσ X2╡ protoco∞ system¼á anΣ t∩ ì
ááááááááreturε contro∞ t∩ thσ CP/═ operatinτ system.

.paè.op





                           APPENDIX II


                       SYSTEM STATUS FLAGS
.paè.pn1
.fo                          II-#
                       System Status Flags


     Thσ followinτ systeφ statu≤ flaτ indicator≤ arσ availablσ t∩ ì
the local user in response to main menu option # 11:

level 1 flags

    definition of rx status (rxstat) byte flags:

    bit    set condition
    0    undefined
    1    undefined
    2    undefined
    3    undefined
    4    undefined
    5    receiver buffers unavailable
    6    undefined
    7    undefined

    definition of tx status (txstat) byte flags:

    bit    set condition
    0    tx active
    1    tx message complete
    2    tx frame underrun
    3    next tx character is control
    4    undefined
    5    undefined
    6    undefined
    7    undefined

.cp10
    definition of timer status (tistat) byte flags:

    bit    set condition
        0    level 2 timer t1 timed out
    1    level 3 timer t20 timed out
    2    level 3 timer t21 timed out
    3    level 3 timer T22 timed out
    4    level 3 timer T23 timed out
    5    undefined
    6    undefined
    7    undefined


.cp15èlevel 2 flags

    definition of link status (lkstat) byte flags:

    bit    set condition
    0    link connect in process
    1    link disconnect in process
    2    link connected
    3    DCE busy
    4    DTE busy (from level 1 module)
    5    unassigned
    6    DTE REJ condition
    7    DCE REJ condition

.cp10
        definition of poll/final (P/F) byte flags:

        bit     set condition
        0       =0 always
        1       =0 always
        2       =0 always
        3       =0 always
        4       poll/final bit
        5       =0 always
        6       =0 always
        7       =0 always

.cp10
    definition of flow status (l2stat) byte flags:

    bit    set condition
    0    link query in process
    1    DTE FRMR condition
    2    DCE FRMR condition
    3    unassigned
    4    unassigned
    5    unassigned
    6    retransmit old I frame
    7    timer recovery condition


.cp15
level 3 flags


    definition of channel status (chstat) byte flags:
    (note that state r1 (packet level ready)
     corresponds to level 2 link connected)

    bit    set condition
    0    flow control ready state (d1)
    1    DTE restart request state (r2)
    2    DTE waiting state (p2)
    3    DTE reset request state (d2)
    4    DTE clear request state (p6)
    5    ready (p1)
    6    undefined
    7    undefinedè
    definition of flow control (l3stat) byte flags:

    bit    set condition
    0    DTE busy
    1    DCE busy
    2    DTE interrupt pending confirmation
    3    undefined
    4    undefined
    5    undefined
    6    transmission completed - ready to clear
    7    outgoing message waiting for call setup

.cp10

        definition of Qualifier (Q) byte flags:

        bit     set condition
        0       =0 always
        1       =0 always
        2       =0 always
        3       =0 always
        4       =0 always
        5       =0 always
        6       =0 always
        7       Q bit

        definition of Delivery Confirmation (D) byte flags:

        bit     set condition
        0       =0 always
        1       =0 always
        2       =0 always
        3       =0 always
        4       =0 always
        5       =0 always
        6       D bit
        7       =0 always


.cp15
level 4 flags

    definition of flow status (l4stat) byte flags:

    bit    set condition
    0    prompt console for packet input
    1    unasigned
    2    unasigned
    3    unasigned
    4    unasigned
    5    unasigned
    6    unasigned
    7    unasigned


èdisk file flags

    definition of disk file status (fstat) byte flags:

    bit    set condition
    0    receive file open
    1    transmit file open
    2    undefined
    3    undefined
    4    undefined
    5    undefined
    6    undefined
    7    log file open

.paè.op





                          APPENDIX III


                SYSTEM STATUS AND ERROR MESSAGES
.paè.fo                         III-#
.pn1
     Thσá followinτá i≤ ß completσ listinτ oµ al∞á systeφá statu≤ ì
message≤ anΣ erro≥ messages«á  Thσ genera∞ forma⌠ oµ systeφ erro≥ ì
message≤ i≤ a≤ follows:


                Ln: message [- action performed]


     where     n =  protocol level generating the message

             1 = hardware level
             2 = link (frame) level
             3 = packet level
                 4 = user level

    Thσ systeφ modulσ namσ generatinτ thσ messagσ i≤ showε iε ì
parenthesis after each message.



Hardware Level (L1:) Messages


     Therσá arσá n∩á use≥á message≤á generateΣá b∙á thσá hardwarσ ì
protocol level.



Link Level (L2:) Messages

L2║ linδ connectedé (X25.ASM⌐ - thi≤ statu≤ messagσ indicate≤ tha⌠ ì
the link level is presently connected.

L2║á waitinτá fo≥ linδ connec⌠ froφ DCEé  (X25.ASM⌐ - thi≤á statu≤ ì
messagσá indicate≤ tha⌠ thσ linδ leve∞ i≤ presentl∙ no⌠ connecteΣ ì
and that no link connect action has been initiated by the system.

L2║áá attemptinτá linδá connect...éá  (LEVEL2.ASM⌐á - thi≤á statu≤ ì
messagσáá i≤á displayeΣá wheεá thσá firs⌠á SAB═á framσá i≤á beinτ ì
transmitteΣ a≤ ß resul⌠ oµ systeφ men⌡ optioε ú ▒ beinτ selected.

L2║á attemptinτ linδ disconnect...é  (LEVEL2.ASM⌐  -  thi≤á statu≤ ì
messagσáá i≤á displayeΣá wheεá thσá firs⌠á DIS├á framσá i≤á beinτ ì
transmitteΣ a≤ ß resul⌠ oµ systeφ men⌡ optioε ú ╣ beinτ selected.

L2║á  linδá i≤á alread∙ disconnectedé  (LEVEL2.ASM⌐  - thi≤á erro≥ ì
messagσ i≤ displayeΣ wheε systeφ men⌡ optioε ú ╣ i≤ selecteΣá anΣ ì
te link is already disconnected.

L2║á dtσá linδ i≤ disconnectedé (LEVEL2.ASM⌐ - thi≤ statu≤ messagσ ì
i≤ displayeΣ iε repl∙ t∩ ß linδ quer∙ (wheε systeφ men⌡ optioεá ú ì
╕ i≤ selecteΣ) iµ thσ linδ i≤ disconnected.

L2║ dtσ FRMR/CMD╥ conditioné (LEVEL2.ASM⌐ - thi≤ statu≤ messagσ i≤ ì
displayeΣá iε repl∙ t∩ ß linδ quer∙ iµ ß commanΣ o≥ framσá rejec⌠ ìèconditioε exist≤ iε thσ system«

L2║á dtσá busyé (LEVEL2.ASM⌐ - thi≤ statu≤ messagσ i≤ displayeΣ iε ì
reply to a link query if the system dte busy flag is set.

L2║á dtσá iε framσ rejec⌠ conditioné  (LEVEL2.ASM⌐á - thi≤á statu≤ ì
messagσ i≤ displayeΣ iε repl∙ t∩ ß linδ quer∙ iµ thσ systeφ i≤ iε ì
a frame sequence reject condition.

L2║á dtσ readyé (LEVEL2.ASM⌐ - thi≤ statu≤ messagσ i≤ displayeΣ iε ì
repl∙á t∩ ß linδ quer∙ conditioε iµ thσ linδ i≤ connecteΣ anΣ thσ ì
systeφ i≤ no⌠ iε ß CMDR/FRM╥ dtσ bus∙ o≥ dtσ rejec⌠ condition.

L2║áá interrogatinτá dcσá status...éá (LEVEL2.ASM⌐á - thi≤á statu≤ ì
messagσá i≤á displayeΣ durinτ ß linδ quer∙ wheε ß framσ i≤á beinτ ì
sen⌠á t∩ thσ dcσ witΦ thσ pol∞ bi⌠ se⌠ t∩ ▒ iε orde≥ t∩á forcσá ß ì
repl∙ froφ thσ dce.

SAB═á trie≤á t∩á g∩ ╜ né (LEVEL2.ASM⌐ - thi≤ progres≤á messagσá i≤ ì
displayeΣ wheε ß linδ connec⌠ i≤ iε proces≤ anΣ transmissioε oµ ß ì
SABM frame is being retried.


DIS├á trie≤á t∩ g∩ ╜ né  (LEVEL2.ASM⌐ - thi≤ progres≤á messagσá i≤ ì
displayeΣá wheε ß linδ disconnec⌠ i≤ iε proces≤ anΣá transmissioε ì
of a DISC frame is being retried.

quer∙á trie≤ t∩ g∩ ╜ né  (LEVEL2.ASM⌐ - thi≤ progres≤á messagσá i≤ ì
displayeΣá wheε ß linδ quer∙ i≤ iε proces≤ anΣ transmissioε oµá ß ì
RR, RNR, or REJ frame is being retried.

L2║á T▒á timeΣ ou⌠ - retransmittinτ ╔ framσ ε - trie≤ t∩ g∩á ╜á ké  ì
(LEVEL2.ASM⌐ - thi≤ progres≤ messagσ i≤ displayeΣ wheε aε ╔ framσ ì
ha≤á no⌠á beeεá acknowledgeΣá iε thσ timeou⌠á perioΣá anΣá i≤á iε ì
retransmissioε i≤ iε process.

L2║á t° retr∙ coun⌠ exhausteΣ - n∩ repl∙ froφ DCEé  (LEVEL2.ASM⌐ - ì
thi≤áá statu≤áá messagσáá i≤á displayeΣá wheεáá thσáá numbe≥áá oµ ì
retransmission≤ oµ ß SABM¼á DISC¼ RR¼ RN╥ o≥ ╔ framσ ha≤ exceedeΣ ì
thσ maximuφ value.

L2║á disconnectinτá linkéá (LEVEL2.ASM⌐ - thi≤ statu≤á messagσá i≤ ì
displayeΣ afte≥ thσ retr∙ coun⌠ i≤ exhausteΣ wheε thσ systeφ wil∞ ì
attempt to disconnect the link.

L2║á r°á empt∙ framσ (n∩ contro∞ byte)é (LEVEL2.ASM⌐ - thi≤á erro≥ ì
messagσ indicate≤ tha⌠ aε empt∙ framσ ha≤ beeε passeΣ t∩ thσ linδ ì
level handler from the interrupt hardware handler.

L2: rx bad address:
  L2║á framσá contents:éá (LEVEL2.ASM⌐ - thi≤ debuτ erro≥á messagσ ì
indicate≤á tha⌠ ß framσ havinτ aε addres≤ othe≥ thaε ┴ o≥á ┬á ha≤ ì
beeεá received«á  Iµ thσ debuτ optioε h≤ beeε enableΣá a⌠á modulσ ì
assembl∙ time the contents of the frame are dumped in hex.
èL2║á r°á SAB═ - linδ connecteΣ b∙ dceé  (LEVEL2.ASM⌐ - thi≤ statu≤ ì
messagσ indicate≤ tha⌠ ß thσ linδ ha≤ beeε connecteΣ b∙ receptioε ì
oµ ß SAB═ framσ froφ thσ dce.

L2║á r°á DIS├á - linδ disconnecteΣ b∙á dceéá  (LEVEL2.ASM⌐á - thi≤ ì
statu≤á messagσ indicate≤ tha⌠ thσ linδ ha≤ beeε disconnecteΣá b∙ ì
reception of a DISC frame from the dce.

L2║áá baΣá receiveΣá N(r)éá  (LEVEL2.ASM⌐á - thi≤á erro≥áá messagσ ì
indicate≤ tha⌠ ß numbereΣ framσ ha≤ beeε receiveΣ witΦ aε invaliΣ ì
receive sequence number.

L2║ dcσ readyé (LEVEL2.ASM⌐ - thi≤ statu≤ messagσ indicate≤ tha⌠ ß ì
R╥ framσ ha≤ beeε receiveΣ iε repl∙ t∩ ß linδ query.

L2║ dcσ busyé (LEVEL2.ASM⌐ - thi≤  statu≤ messagσ indicate≤ tha⌠ ß ì
RNR frame has been received in reply to a link query.

L2║á dcσá iεá RE╩ conditioné  (LEVEL2.ASM⌐ - thi≤á statu≤á messagσ ì
indicate≤á tha⌠ ß RE╩ framσ ha≤ beeε receiveΣ iε repl∙ t∩ ßá linδ ì
query.

L2║á r°á D═á - dcσ unablσ t∩ connecté (LEVEL2.ASM⌐á - thi≤á statu≤ ì
message indicates that a DM frame has been received from the DCE.

L2║á r°á U┴ - linδ connectedé (LEVEL2.ASM⌐ - thi≤á statu≤á messagσ ì
indicate≤ tha⌠ ß U┴ framσ ha≤ beeε receiveΣ froφ thσ DC┼ iε repl∙ ì
to a previously transmitted SABM frame, thus connecting the link.

L2║ r° U┴ - linδ disconnectedé  (LEVEL2.ASM⌐ - thi≤ statu≤ messagσ ì
indicate≤ tha⌠ ß U┴ framσ ha≤ beeε receiveΣ froφ thσ DC┼ iε repl∙ ì
t∩á ß previousl∙ transmitteΣ DIS├ frame¼á thu≤ disconnectinτá thσ ì
link.

L2: rx CMDR/FRMR - frame rejected:
      rejected frame id =
      rejected frame type = response/command
      erro≥á bit≤á zyxw╜ éá                        (LEVEL2.ASM⌐á - ì
thi≤á statu≤á messagσ indicate≤ tha⌠ ß CMDR/FRM╥ framσá ha≤á beeε ì
received from the DCE.



Packet Level (L3:) Messages:



L3║ r° empt∙ ╔ frameé  (LEVEL2.ASM⌐ - thi≤ erro≥ messagσ indicate≤ ì
tha⌠ aε ╔ framσ ha≤ beeε receiveΣ witΦ correc⌠ forma⌠ bu⌠ witΦ aε ì
empt∙ ╔ field.

L3║á linδá no⌠á connecteΣ - canno⌠ senΣ interrupté (LEVEL3.ASM⌐á - ì
thi≤ erro≥ messagσ indicate≤ tha⌠ thσ requesteΣ interrup⌠á canno⌠ ì
bσá transmitteΣ becausσ thσ leve∞ ▓ linδ connectioε ha≤ no⌠á beeε ì
established.è
L3║áá linδá no⌠á iεá datßá xfe≥á statσá - canno⌠á senΣá interrupté  ì
(LEVEL3.ASM⌐á - thi≤á erro≥ messagσ indicate≤ tha⌠ thσá requesteΣ ì
interrup⌠á canno⌠ bσ transmitteΣ becausσ thσ leve∞ │á channe∞á i≤ ì
no⌠ iε thσ flo≈ contro∞ read∙ state.

L3║ DT┼ interrup⌠ i≤ pendinτ - canno⌠ senΣ interrupté (LEVEL3.ASM⌐ ì
- thi≤á erro≥á messagσá indicate≤ tha⌠á thσá requesteΣá interrup⌠ ì
canno⌠ bσ transmitteΣ becausσ ß previousl∙ transmitteΣá interrup⌠ ì
has not yet been acknowledged.

L3║áá linδáá no⌠á connectedéá (LEVEL3.ASM⌐á - thi≤á erro≥á messagσ ì
indicate≤á tha⌠á thσ requesteΣ restar⌠ reques⌠ packe⌠á canno⌠á bσ ì
transmitted because the level 2 link is not connected.

L3║áá T2░á timeΣá ou⌠á - retransmittinτá restar⌠á reques⌠á packeté ì
(LEVEL3.ASM⌐á - thi≤á erro≥ messagσ indicate≤ tha⌠á ßá previousl∙ ì
transmitteΣá restar⌠á reques⌠á packe⌠ wa≤á no⌠á acknowledgeΣá anΣ ì
anothe≥ restar⌠ reques⌠ i≤ beinτ transmitted.

L3║á t° retr∙ coun⌠ exhausteΣ - n∩ repl∙ froφ DCEé  (LEVEL3.ASM⌐ - ì
thi≤ erro≥ messagσ indicate≤ tha⌠ n∩ repl∙ t∩ thσ restar⌠ reques⌠ ì
packe⌠ ha≤ beeε receiveΣ afte≥ thσ alloweΣ numbe≥ oµ retries.

L3║áá T2▒áá timeΣáá ou⌠á - transmittinτá clea≥áá reques⌠áá packeté ì
(LEVEL3.ASM⌐á - thi≤á erro≥ messagσ indicate≤ tha⌠ n∩á repl∙á ha≤ ì
beeε receiveΣ t∩ ß previousl∙ transmitteΣ cal∞ reques⌠ packe⌠ anΣ ì
tha⌠ ß clea≥ reques⌠ packe⌠ i≤ beinτ transmitted.

L3║áá T2▓áá timeΣá ou⌠á - retransmittinτá rese⌠á reques⌠áá packeté ì
(LEVEL3.ASM⌐á - thi≤á erro≥ messagσ indicate≤ tha⌠ n∩á repl∙á ha≤ ì
beeεá receiveΣá t∩ ß previousl∙ transmitteΣ rese⌠ reques⌠á packe⌠ ì
and that another reset request is being retransmitted.

L3║áá T2│áá timeΣá ou⌠á - retransmittinτá clea≥á reques⌠áá packeté  ì
(LEVEL3.ASM⌐á - thi≤á erro≥ messagσ indicate≤ tha⌠ n∩á repl∙á ha≤ ì
beeεá receiveΣ t∩ ß previousl∙ transmitteΣ clea≥á reques⌠á packe⌠ ì
and that another clear request is being retransmitted.

L3║á t°á retr∙á coun⌠á exhausteΣ - logica∞ channe∞ ou⌠á oµá orderé  ì
(LEVEL3.ASM⌐á - thi≤á erro≥ messagσ indicate≤ tha⌠ n∩á repl∙á ha≤ ì
beeεá receiveΣá t∩á retransmission≤ duσ t∩ T2▓ o≥ T2│á timσá out≤ ì
after the maximum number of retransmissions permitted.

L3║áá r°á cal∞á connectedéá (LEVEL3.ASM⌐á - thi≤á statu≤áá messagσ ì
indicate≤á tha⌠á thσ channe∞ ha≤ beeε placeΣ iε thσ flo≈á contro∞ ì
read∙á statσ b∙ ß cal∞ connecteΣ packe⌠ receiveΣ froφ thσ DC┼á iε ì
reply to a previously transmitted call request packet.

L3║á baΣá addres≤á - t° clea≥ requesté (LEVEL3.ASM⌐á - thi≤á erro≥ ì
messagσ indicate≤ tha⌠ ß cal∞ connecteΣ packe⌠ ha≤ beeεá receiveΣ ì
witΦá aε invaliΣ addres≤ anΣ tha⌠ ß clea≥ reques⌠ packe⌠ i≤ beinτ ì
transmitted.

L3║á cal∞á refuseΣ - t° clea≥ requesté  (LEVEL3.ASM⌐ - thi≤á erro≥ ìèmessagσ indicate≤ tha⌠ thσ incominτ cal∞ packe⌠ i≤ beinτá refuseΣ ì
and that a clear request packet is being transmitted in reply.

L3║á r°á clea≥ indicatioε packet¼á causσ ╜ né (LEVEL3.ASM⌐á - thi≤ ì
statu≤á messagσ indicate≤ tha⌠ ß clea≥ indicatioε packe⌠ ha≤ beeε ì
received¼á thu≤ terminatinτ thσ existinτ call«  ┴ diagnostiπ codσ ì
, if transmitted follows the above message.

L3║á r°á clea≥á confirmatioε packeté  (LEVEL3.ASM⌐á - thi≤á statu≤ ì
messagσá indicate≤á tha⌠á ß clea≥ confirmatioεá packe⌠á ha≤á beeε ì
receiveΣá iεá repl∙á t∩ ß previousl∙á transmitteΣá clea≥á reques⌠ ì
packet, thus terminating the existing call.

L3║á r°á IN╘á packe⌠ - use≥ data║á é  (LEVEL3.ASM⌐á - thi≤á statu≤ ì
messagσá indicate≤á tha⌠ aε interrup⌠ packe⌠ ha≤á beeεá received¼ ì
witΦ thσ use≥ datß codσ a≤ shown.

L3║á r°á interrup⌠ confirmatioε packeté (LEVEL3.ASM⌐ - thi≤ statu≤ ì
messagσ indicate≤ tha⌠ aε interrup⌠ confirmatioε packe⌠ ha≤á beeε ì
received in reply to a previously transmitted interrupt packet.

L3║á r°á DIA╟á packe⌠ - diagnostiπ ú n
  L3║á  diagnostiπá explanation║á é           (LEVEL3.ASM⌐á - thi≤ ì
erro≥á messagσá indicate≤á tha⌠á ßá diagnostiπá packe⌠á ha≤á beeε ì
receiveΣá witΦ thσ codσ a≤ shown«á  Iµ ßá diagnostiπá explanatioε ì
fielΣá i≤ includeΣ iε thσ diagnostiπ message¼á thσ seconΣ par⌠ oµ ì
thσ messagσ wil∞ appear.

L3║á r° restarté (LEVEL3.ASM⌐ - thi≤ statu≤ messagσ indicate≤ tha⌠ ì
ß restar⌠ packe⌠ ha≤ beeε receiveΣ anΣ tha⌠ thσ packe⌠ leve∞ flo≈ ì
contro∞ variable≤ havσ beeε rese⌠ t∩ thei≥ origina∞ values«

L3║ loca∞ procedurσ erro≥ - resettinτ channelé (LEVEL3.ASM⌐ - thi≤ ì
erro≥á messagσá indicate≤ tha⌠ aε erro≥ ha≤ beeε detecteΣ iεá thσ ì
receiveΣá packe⌠á transmi⌠á sequencσ numbe≥á P(s⌐á anΣá tha⌠á thσ ì
channel is being reset by transmission of a reset request packet.


User Interface (L4:) Messages

L4║á consolσá inpu⌠á buffe≥á overflowé  (XUTIL.ASM⌐á - thi≤á erro≥ ì
messagσá indicate≤á tha⌠ thσ consolσ inpu⌠ buffe≥á ha≤á no⌠á beeε ì
cleared and that typed characters are being lost.

L4║á transmi⌠á filσá i≤á alread∙ openéá (FILES.ASM⌐á - thi≤á erro≥ ì
messagσá indicate≤á tha⌠ thσ requesteΣ transmi⌠á filσá canno⌠á bσ ì
openeΣ becausσ ß transmi⌠ filσ i≤ alread∙ open.

L4║á filσá no⌠ foundé  (FILES.ASM⌐ - thi≤ erro≥ messagσá indicate≤ ì
tha⌠á thσ transmi⌠ filσ canno⌠ bσ openeΣ becausσ n∩ filσ b∙á tha⌠ ì
name exists.

L4║á filσá transmissioεá iεá processéá (FILES.ASM⌐á - thi≤á statu≤ ì
messagσá indicate≤ tha⌠ ß transmi⌠ filσ ha≤ beeε openeΣ anΣá tha⌠ ì
the packet level channel is in flow control ready state.è
L4║á read∙á t∩ transmi⌠ fileé  (FILES.ASM⌐ - thi≤á statu≤á messagσ ì
indicate≤á tha⌠á ßá transmi⌠ filσ ha≤ beeε openeΣá bu⌠á tha⌠á thσ ì
packet level channel is not in flow control ready state.

L4║á transmi⌠á filσá closedéá (FILES,ASM⌐á - thi≤á statu≤á messagσ ì
indicates that the transmit file has been closed.

L4║ receivσ filσ i≤ alread∙ opené (FILES.ASM⌐ - thi≤ erro≥ messagσ ì
indicate≤á tha⌠á thσá requesteΣá receivσ filσá canno⌠á bσá openeΣ ì
becausσ a receive file is already open.

L4║á receivσá filσ opeε - awaitinτ dataé (FILES.ASM⌐ - thi≤ statu≤ ì
messagσá indicate≤á tha⌠á thσ requesteΣá receivσá filσá ha≤á beeε ì
successfull∙á openeΣá anΣ tha⌠ al∞ receiveΣ datß wil∞ bσá writteε ì
ont∩ thσ file.

L4║áá receivσá filσá closedéá (FILES.ASM⌐á - thi≤á statu≤á messagσ ì
indicate≤ tha⌠ thσ receivσ filσ ha≤ beeε closed.

L4║á filσá namσ erroré (FILES.ASM⌐  - thi≤ erro≥ messagσ indicate≤ ì
that the requested file name is not a valid file name.

L4║á framσá logginτá enabledé  (FILES.ASM⌐ - thi≤á statu≤á messagσ ì
indicate≤ tha⌠ thσ sessioε loτ filσ ha≤ beeε successfull∙á openeΣ ì
anΣá tha⌠ al∞ subsequen⌠ frame≤ wil∞ bσ loggeΣ oε thσ sessioε loτ ì
file.

L4║á framσá logginτá disabledé  (FILES.ASM⌐ - thi≤ statu≤á messagσ ì
indicate≤á tha⌠ thσ sessioε loτ filσ ha≤ beeε closeΣ anΣ tha⌠á n∩ ì
more frames are being logged in the session file.