Oakland CPM Archive/oakcpm.iso/sigm/vol200/z3lib3.hqp/Z3LIB3.HLP

Text File | 1985-02-10 | 19.4 KB | 657 lines

Introduction                  ZCPR3 Messages
Command Status Message        
GETCST/PUTCST/QERROR/QSHELL
Erro≥ Flaτ anΣ Erro≥ CommanΣ  
ERRADR/GETER1/PUTER1/GETERC/PUTERC
Inter-Transient Error Code    
GETER2/PUTER2
Register Access               
GETREG/PUTREG
ZEX Status and Control        
GETZEX/PUTZEX/STOPZEX/STRTZEX
:Introduction to ZCPR3 Messages

     ZCPR│ offer≤ man∙ feature≤ no⌠ founΣ unde≥ CP/M¼ ZCPR1¼ ì
o≥ ZCPR2«á  Onσ sucΦ very¼á ver∙ specia∞ featurσ i≤ tha⌠á oµ ì
ZCPR│ CommanΣ Processo≥ Messages.

     ZCPR│á support≤á thσá abilit∙ t∩ havσ ßá ZCPR│á Messagσ ì
Buffe≥á whicΦá contain≤ ß numbe≥ oµ message≤á whicΦá caεá bσ ì
passeΣá froφá onσá transien⌠ prograφ t∩ anothe≥á o≥á betweeε ì
ZCPR│á itselµá anΣ al∞ transien⌠ program≤á whicΦá ruεá unde≥ ì
ZCPR3«á  Command≤á caεá bσ giveε directl∙ t∩á ZCPR3¼á statu≤ ì
informatioε caε bσ passeΣ froφ ZCPR│ t∩ thσ transients¼á anΣ ì
botΦ statu≤ anΣ command≤ caε bσ passeΣ froφ onσ transien⌠ t∩ ì
anothe≥ througΦ thesσ messages.


     These message can be divided into six basic classes:

          . messages which command ZCPR3
          . status messages sent by ZCPR3
          . ZEX command messages
          . status and command messages sent by one program
               to another which are ignored by ZCPR3
          . user-defined messages
          . reserved messages


     Beforσá usinτ an∙ oµ thσ Z3LI┬ routine≤ t∩ acces≤ thesσ ì
messages¼á thσ prograφ shoulΣ checδ t∩ ensurσ tha⌠ thσ ZCPR│ ì
Messagσ Buffe≥ i≤ availablσ t∩ it«á  Thi≤ caε bσ easil∙ donσ ì
b∙á callinτ thσ GETMS╟ routinσ (seσ thσ seconΣ oε thσá ZCPR│ ì
environment)«á  GETMS╟ return≤ witΦ Zer∩ Flaτ Se⌠ (Z⌐ iµá n∩ ì
ZCPR3 Message Buffer exists.  Hence:

          ext  getmsg    ;reference
          ...
          call getmsg    ;get message buffer status
          jz   noZ3msgs  ;no messages to read
          ...

     Thσáá followinτáá screen≤á summarizσáá thσáá facilitie≤ ì
availablσ througΦ thσ ZCPR│ Messagσ Buffer.


                Messages which Command ZCPR3
                -------- ----- ------- -----

     Somσá oµá thσ message≤ iε thσ ZCPR│ Messagσ Buffe≥á arσ ì
se⌠á b∙ externa∞ program≤ (transient≤ o≥á commanΣá packages⌐ ì
and are read and interpreted by ZCPR3.  These messages are:

          . current IF level and active (T/F) status of
               all IF levels
          . whether an error handler is available and what
               the command line to invoke it is



               Status Messages Sent by ZCPR3
               ------ -------- ---- -- -----

     Somσá oµá thσ message≤ iε thσ ZCPR│ Messagσ Buffe≥á arσ ì
se⌠á onl∙ b∙ ZCPR│ o≥ ß ZCPR│ Shel∞ anΣ arσ intendeΣá t∩á bσ ì
useΣ a≤ R/╧ message≤ b∙ transients«  Thesσ message≤ are:

          . ZCPR3 Command Status
               - the transient loaded is/is not a shell
               - the transient loaded is/is not an error
                    handler
          . Error Address
               - iµ thσ transien⌠ loadeΣ i≤ aε erro≥
                    handler, this is the address of the
                    firs⌠ characte≥ oµ thσ commanΣ linσ
                    which was in error


                    ZEX Command Messages
                    --- ------- --------

     Onσ messagσ iε thσ ZCPR│ Messagσ Buffer≤ i≤ intendeΣ t∩ ì
directl∙ senΣ command≤ t∩ thσ ZE╪ memory-baseΣ commanΣá filσ ì
processor«á  Thi≤á messagσá bytσ tell≤ ZE╪á threσá differen⌠ ì
things:

          . to run normally - ZEX is to intercept the
               Input calls and provide characters in place
               of console input
          . ZCPR3 is prompting - ZEX is providing input
               directly to the Command Processor ZCPR3
          . suspend intercept - ZEX is to stop intercepting
               console input and to allow input from the
               console until normal execution or the ZCPR3
               prompt message appears


                 Messages Ignored by ZCPR3
                 -------- ------- -- -----

     Tw∩á pre-defineΣá message≤ arσ ignoreΣ b∙á ZCPR3«á  Thσ ì
firs⌠ messagσ i≤ thσ Prograφ Erro≥ Code«á  Thi≤ bytσ caεá bσ ì
se⌠á b∙ an∙ prograφ unde≥ ZCPR│ t∩ indicatσ ß returεá statu≤ ì
t∩á thσ nex⌠ program«á  Thσ conventioε ha≤ beeε adopteΣ tha⌠ ì
iµ thi≤ bytσ i≤ 0¼á theε thσ prograφ completeΣ successfully«  ì
Iµá i⌠á i≤ non-zero¼á thσ prograφ faileΣ fo≥ onσá reasoεá o≥ ì
anothe≥ anΣ thσ valuσ oµ thi≤ codσ indicate≤ tha⌠ reasoεá t∩ ì
ß followinτ program.

     Thσ seconΣ messagσ i≤ thσ registe≥ buffer«á  Teε 1-bytσ ì
register≤á arσá availablσá anΣá caε bσ testeΣá b∙á thσá flo≈ ì
commanΣ package«á  Condition≤ likσ "I╞ ░ 5ó (I╞ Registe≥ ░ ╜ ì
5⌐á caεá bσá testeΣ fo≥ anΣ processeΣ b∙á thσá flo≈á commanΣ ì
package¼á anΣ othe≥ programs¼á eithe≥ transient≤ o≥ residen⌠ ì
command packages, can manipulate these register values.

                   User-Defined Messages
                   ------------ --------

     ┴ se⌠ oµ 1╢ message≤ arσ availablσ fo≥ use≥ definition«  ì
EacΦá messagσ i≤ onσ bytσ long¼á anΣ routine≤ iεá Z3LI┬á arσ ì
provided to place values into these messages and query them.


                     Reserved Messages
                     -------- --------

     ┴á se⌠á oµ 1╢ one-bytσ message≤ i≤ reserveΣ fo≥á futurσ ì
usσá iεá thσá ZCPR│á systeφá anΣá shoulΣá no⌠á bσá useΣáá b∙ ì
application≤ programmers«á  Z3LI┬ doe≤ no⌠ providσ acces≤ t∩ ì
these messages.

:Command Status Message        GETCST/PUTCST/QERROR/QSHELL

     Thesσáá message≤á returεá thσá statu≤á oµá thσá curren⌠ ì
transien⌠ a≤ se⌠ b∙ ZCPR3«á  An∙ transien⌠ ha≤ beeεá invokeΣ ì
in one of three possible states:

          . as a "normal" transient, executed at the
               request of the user or another program
          . as a "shell", invoked by ZCPR3 itself
          . as an "error handler", invoked by ZCPR3 itself
               when it cannot process the current command
               line (cannot find a matching COM file or
               CMDRUN facility)



Z3LIB Routine: GETCST


Function:
     Returε thσ ZCPR│ CommanΣ Statu≤ Message«á  Thi≤ messagσ ì
is one byte long and can have one of three values:

          0 - this is a "normal" transient
          1 - this is a "shell"
          2 - this is an "error handler"

     Thi≤ messagσ i≤ alway≤ se⌠ b∙ ZCPR│ anΣ no⌠ intendeΣ t∩ ì
be set by any program.


Inputs: None


Outputs: A = message code (Zero Flag set accordingly)



Registers Affected: PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: PUTCST


Function:
     Se⌠ thσ ZCPR│ CommanΣ Statu≤ Message«á  Thi≤ messagσ i≤ ì
onσ bytσ lonτ anΣ caε havσ onσ oµ threσ values:

          0 - this is a "normal" transient
          1 - this is a "shell"
          2 - this is an "error handler"

     Thi≤ messagσ i≤ alway≤ se⌠ b∙ ZCPR│ anΣ no⌠ intendeΣ t∩ ì
bσ se⌠ b∙ an∙ program¼á witΦ thσ exceptioε oµ ß ZCPR│ Shell«  ì
PUTCS╘ i≤ provideΣ t∩ allo≈ ß ZCPR│ Shel∞ eas∙ acces≤ t∩ se⌠ ì
this message byte.


Inputs: A = ZCPR3 Command Status Message value (0, 1, or 2)


Outputs: None



Registers Affected: None


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: QERROR


Function:
     Tes⌠á t∩á seσá iµá thσá ZCPR│á CommanΣá Statu≤á Messagσ ì
indicate≤á tha⌠á thσ curren⌠ transien⌠ i≤ aε erro≥á handler«  ì
Thσ ZCPR│ CommanΣ Statu≤ Messagσ i≤ reaΣ anΣ testeΣá agains⌠ ì
thσá Erro≥á Handle≥á codσ value«á  Zer∩ Flaτ i≤ Se⌠á iµá thσ ì
current transient is an Error Handler«


Inputs: None


Outputs: A = message code
          Zero Flag is Set if transient is an Error Handler



Registers Affected: PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: QSHELL


Function:
     Tes⌠á t∩á seσá iµá thσá ZCPR│á CommanΣá Statu≤á Messagσ ì
indicate≤ tha⌠ thσ curren⌠ transien⌠ i≤ ß shell«á  Thσ ZCPR│ ì
CommanΣ Statu≤ Messagσ i≤ reaΣ anΣ testeΣ agains⌠ thσá Shel∞ ì
codσ value«á  Zer∩ Flaτ i≤ Se⌠ iµ thσ curren⌠ transien⌠ i≤ ß ì
Shell.


Inputs: None


Outputs: A = message code
          Zero Flag is Set if transient is a Shell



Registers Affected: PSW


Side Effects: None


Special Error Conditions: None


:Error Flag and Error Command  ERRADR/GETER1/PUTER1/GETERC/PUTERC

     This set of routines performs the following functions:

          ERRAD╥ - return≤ thσ addres≤ oµ thσ firs⌠
               character of the command line in error
          GETER1 - returns the error flag
          PUTER1 - sets the error flag
          GETERC - returns the address of the first
               character of the error handler command line
          PUTERC - set the error handler command line



Z3LIB Routine: ERRADR


Function:
     Assuminτ tha⌠ thσ curren⌠ transien⌠ i≤ aε erro≥ handle≥ ì
(ß cal∞ t∩ QERRO╥ return≤ witΦ Zer∩ Flaτ Set)¼á thi≤ routinσ ì
return≤á thσ addres≤ oµ thσ firs⌠ characte≥ oµá thσá commanΣ ì
line which was in error.  For example, if the command:

          XXX params;DIR

wa≤á issueΣ anΣ XXX.CO═ coulΣ no⌠ bσ found¼á ERRAD╥á return≤ ì
thσ addres≤ oµ thσ firs⌠ characte≥ oµ thσ string:

          db   'XXX params;DIR',0


Inputs: None


Outputs: HL = address of first character of error line



Registers Affected: HL


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: GETER1


Function:
     Returε thσ erro≥ flaτ iε A«á  GETER▒ allow≤ thσ prograφ ì
t∩ finΣ ou⌠ iµ aε erro≥ handle≥ i≤ currentl∙ installed«  A=░ ì
anΣá Zer∩á Flaτá i≤á Se⌠ (Z⌐ iµ therσ i≤á n∩á erro≥á handle≥ ì
installed.


Inputs: None


Outputs: A=0 and Z if no error handler installed
          A<>0 and NZ if error handler installed


Registers Affected: PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: PUTER1


Function:
     Se⌠á thσ erro≥ handle≥ installeΣ flag«á  PUTER▒á allow≤ ì
thσá prograφá t∩ explictl∙ se⌠ thσ erro≥á handle≥á installeΣ ì
flag«á  Iµ thi≤ flaτ i≤ se⌠ t∩ 0¼á thσ curren⌠ erro≥ handle≥ ì
(iµ any⌐ i≤ disabled«á  Iµ thi≤ flaτ i≤ se⌠ t∩ non-zero¼ thσ ì
curren⌠á erro≥ handle≥ (defineΣ b∙ thσ erro≥ handle≥ commanΣ ì
linσ messagσ - seσ GETERC/PUTERC⌐ i≤ enableΣ fo≥ late≥ use.


Inputs: A = error handler engaged flag
          (A=0 if error handler is to be disabled, A<>0
          if error hander is to be enabled)


Outputs: None



Registers Affected: None


Side Effects: Error Handler Enable Message is Set


Special Error Conditions: None



Z3LIB Routine: GETERC


Function:
     Returεá thσá addres≤á oµ thσá firs⌠á characte≥á oµá thσ ì
command line used to invoke the current error handler.

     If the error handler is to be invoked by the command:

          ERROR params

then the address of the first character of this string:

          db   'ERROR params',0

is returned.

     Iµ therσ i≤ n∩ erro≥ string¼á oε exi⌠ A=░ anΣ Zer∩ Flaτ ì
i≤á Se⌠ (Z)«á  Otherwise¼á A=firs⌠ characte≥ oµ erro≥ strinτ ì
and NZ.


Inputs: None


Outputs: HL = address of first char
          A=0 and Zero Flag Set if string is empty


Registers Affected: HL, PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: PUTERC


Function:
     Se⌠á thσá erro≥ handle≥ commanΣá line«á  Oεá input¼á H╠ ì
point≤ t∩ ß strinτ whicΦ i≤ t∩ bσ thσ commanΣ linσá executeΣ ì
to invoke an error handler.  For example:

          ext  puterc
          ...
          lxi  h,erstr   ;pt to string
          call puterc
          jnz  OK        ;string was accepted
          ...
     erstr:
          db   'ERROR NOOPT',0

     Thσá erro≥ string¼á includinτ thσ endinτ 0¼á mus⌠ bσ 3▓ ì
byte≤á lonτá o≥ less«á  Iµ i⌠ i≤ morσ thaεá 3▓á byte≤á long¼ ì
PUTERC returns with A=0 and Zero Flag Set (Z).


Inputs: HL = address of first character of error handler
          command line


Outputs: A=0 and Zero Flag Set (Z) if command line too long
          (more than 32 bytes)


Registers Affected: PSW


Side Effects: None


Special Error Conditions: None

:Inter-Transient Error Code    GETER2/PUTER2

     Thσá inter-transien⌠á erro≥ codσ i≤ ß one-bytσá messagσ ì
whicΦá an∙á prograφá caεá se⌠á t∩á indicatσá it≤á completioε ì
success«á  Thσá conventioε i≤ adopteΣ tha⌠ iµá thi≤á messagσ ì
bytσá i≤ se⌠ t∩ 0¼á theε thσ prograφ completeΣ successfully«  ì
Iµ thi≤ messagσ bytσ i≤ no⌠ 0¼ theε thσ prograφ haΣ aε erro≥ ì
iεá onσ forφ o≥ anothe≥ anΣ thσ valuσ oµ thi≤á messagσá bytσ ì
indicate≤ thσ error.

     GETER▓á allow≤ ß prograφ t∩ determinσ thσ valuσ oµ thi≤ ì
inter-transien⌠á erro≥ codσ anΣ PUTER▓ allow≤ ßá prograφá t∩ ì
se⌠ thσ valuσ oµ thσ inter-transien⌠ erro≥ code.



Z3LIB Routine: GETER2


Function:
     Returεá thσ valuσ oµ thσ inter-transien⌠ erro≥ codσá iε ì
A.  A=0 and Zero Flag Set (Z) if no error.


Inputs: None


Outputs: A=error code and Zero Flag set accordingly
          A=0 and Zero Flag Set (Z) if no error


Registers Affected: PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: PUTER2


Function:
     Se⌠á thσ valuσ oµ thσ inter-transien⌠ erro≥á code«á  Iµ ì
A=0, the program is indicating that no error occurred.


Inputs: A=error code (A=0 if no error)


Outputs: None


Registers Affected: None


Side Effects: Error Code Message is Set


Special Error Conditions: None

:Register Access               GETREG/PUTREG

     Thσ ZCPR│ Messagσ Buffe≥ provide≤ teε one-bytσ message≤ ì
whicΦ arσ useΣ a≤ one-bytσ registers«  Thσ GETRE╟ anΣ PUTRE╟ ì
routine≤á allo≈á ß prograφ t∩ obtaiε anΣ se⌠ ß valuσ iεá an∙ ì
one of the ten registers.



Z3LIB Routine: GETREG


Function:
     Obtaiε thσ valuσ (iε A⌐ oµ thσ registe≥ whosσ numbe≥ i≤ ì
iε ┬ (B=░ t∩ 9)«á  Oε entry¼ B=registe≥ number¼ anΣ oε exit¼ ì
A=value in register.

     Note║á  GETRE╟ perform≤ n∩ checδ oε thσ validit∙ oµ thσ ì
valuσ iε B¼á usinτ i⌠ a≤ aε offse⌠ int∩ thσ registe≥ buffer«  ì
I⌠ i≤ thσ responsibilit∙ oµ thσ programme≥ t∩ ensurσ tha⌠á ┬ ì
contains a valid register number (0 to 9).

     Example of use:

          ext  getreg
          ...
          mvi  b,5       ;get the value of Register 5
          call getreg
          jz   r5eq0     ;process special case of reg 5 = 0


Inputs: B = register number of register to access


Outputs║ ┴ ╜ valuσ oµ registe≥ anΣ Zer∩ Flaτ i≤ set
          accordingly


Registers Affected: PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: PUTREG


Function:
     Se⌠á thσ valuσ (containeΣ iε A⌐ int∩ ß registe≥á (whosσ ì
number is contained in B).

     Note║á n∩á checδá i≤ madσ t∩ ensurσ tha⌠ ┬á contain≤á ß ì
valiΣá registe≥á number«á  I⌠ i≤ thσ responsibilit∙á oµá thσ ì
programmer to ensure that B contains a value from 0 to 9.

     Example of use:

          ext  putreg
          ...
          mvi  b,9       ;set register 9
          mvi  a,20      ;to 20
          call putreg
          ...


Inputs: B = register number (0 to 9)
          A = register value (0 to 255)


Outputs: None


Registers Affected: None


Side Effects: Register Value is Set


Special Error Conditions: None

:ZEX Status and Control        GETZEX/PUTZEX/STOPZEX/STRTZEX

     Thσá ZE╪ CommanΣ Filσ Facilit∙ (unde≥ ZCPR│ only!⌐á caε ì
bσ controlleΣ b∙ thi≤ se⌠ oµ Z3LI┬ routines«  ZE╪ intercept≤ ì
al∞ BIO╙ call≤ fo≥ input¼á and¼á wheε iε intercep⌠ mode¼á i⌠ ì
provide≤á inpu⌠ froφ tex⌠ containeΣ iε it≤ memory-baseΣ tex⌠ ì
buffe≥á rathe≥á thaε allowinτ thσ use≥ t∩á inpu⌠á character≤ ì
froφá thσ keyboard«á  Thesσ routine≤ arσ useΣ t∩á quer∙á thσ ì
statu≤á oµ ZE╪ anΣ t∩ instruc⌠ ZE╪ t∩ continuσá interceptinτ ì
character≤ o≥ t∩ sto≡ interceptinτ character≤ anΣ allo≈ use≥ ì
input.



Z3LIB Routine: GETZEX


Function:
     Return≤ thσ ZE╪ contro∞ messagσ bytσ iε A«  Thi≤ allow≤ ì
thσá prograφá t∩ finΣ ou⌠ thσ curren⌠ statσ tha⌠ ZE╪ i≤á in«  ì
This control message byte takes on one of three values:

          0 - "normal" - ZEX is running and intercepting
               BIOS calls
          1 - "ZCPR3 Prompt" - ZEX is allowed to run and
               intercept BIOS calls but ZEX thinks that it
               is providing input to the ZCPR3 command
               Processor directly (ZEX is not providing
               input to any program)
          2 - "ZEX suspended" - ZEX is not intercepting
               BIOS calls and user input is allowed


     Thσ codσ oµ ▒ shoulΣ neve≥ bσ seeε b∙ an∙ prograφ sincσ ì
i⌠ i≤ se⌠ b∙ ZCPR│ anΣ cleareΣ t∩ ░ afte≥ ZE╪ ha≤á completeΣ ì
the command line input.

     An∙á ZE╪á contro∞á messagσ i≤ rese⌠ upoεá executioεá oµ ì
ZCPR│á t∩á ░ wheε ZCPR│ i≤ entereΣ anΣ theε t∩á ▒á wheεá thσ ì
ZCPR│á promp⌠ appear≤ (ZCPR│ input)«á  Wheε ZCPR│á complete≤ ì
its input, it resets the ZEX control message to 0.


Inputs: None


Outputs║ ┴ ╜ ZE╪ Contro∞ Messagσ anΣ Zer∩ Flaτ set
         accordingly
          A = 0 if ZEX is intercepting chars
          A = 1 if ZCPR3 input is engaged and ZEX is
               intercepting chars
          A = 2 if ZEX is not intercepting chars



Registers Affected: PSW


Side Effects: None


Special Error Conditions: None



Z3LIB Routine: PUTZEX


Function:
     Set≤á thσ ZE╪ contro∞ messagσ bytσ iε A«á  Thi≤á allow≤ ì
thσá prograφ t∩ se⌠ thσ statσ tha⌠ ZE╪ i≤ in«á  Thi≤ contro∞ ì
messagσ bytσ mus⌠ takσ oε onσ oµ threσ values:

          0 - "normal" - ZEX is running and intercepting
               BIOS calls
          1 - "ZCPR3 Prompt" - ZEX is allowed to run and
               intercept BIOS calls but ZEX thinks that it
               is providing input to the ZCPR3 command
               Processor directly (ZEX is not providing
               input to any program)
          2 - "ZEX suspended" - ZEX is not intercepting
               BIOS calls and user input is allowed

     I⌠á i≤á thσá responsibilit∙ oµ thσá programme≥á tha⌠á ┴ ì
contains one of these three values upon entry to PUTZEX.

     Thσ codσ oµ ▒ ma∙ bσ se⌠ b∙ an∙ prograφ iµ i⌠ want≤ ZE╪ ì
t∩ "thinkó tha⌠ i⌠ i≤ providinτ inpu⌠ t∩ ZCPR3«á  Iµ ZE╪ wa≤ ì
previousl∙á suspended¼á i⌠ advance≤ t∩ thσ beginninτ oµá thσ ì
nex⌠ linσ anΣ resume≤ wheε i⌠ see≤ thi≤ code.

     An∙á ZE╪á contro∞á messagσ i≤ rese⌠ upoεá executioεá oµ ì
ZCPR│á t∩á ░ wheε ZCPR│ i≤ entereΣ anΣ theε t∩á ▒á wheεá thσ ì
ZCPR│á promp⌠ appear≤ (ZCPR│ input)«á  Wheε ZCPR│á complete≤ ì
its input, it resets the ZEX control message to 0.


Inputs║ ┴ ╜ ZE╪ Contro∞ Messagσ
          A = 0 if ZEX is intercepting chars
          A = 1 if ZCPR3 input is engaged and ZEX is
               intercepting chars
          A = 2 if ZEX is not intercepting chars


Outputs: None



Registers Affected: None


Side Effects: ZEX Control Message Byte is Set


Special Error Conditions: None



Z3LIB Routine: STOPZEX


Function:
     Sto≡á ZE╪á froφ interceptinτ BIO╙ call≤ anΣá allo≈á thσ ì
user to input characters.

     Thi≤ i≤ ß shorthanΣ t∩ placinτ thσ 2 contro∞ codσá int∩ ì
the ZEX Control Message Byte.


Inputs: None


Outputs: None


Registers Affected: None


Side Effects: ZEX Control Message Byte is set to 2


Special Error Conditions: None



Z3LIB Routine: STRTZEX


Function:
     Allo≈á ZE╪ t∩ intercep⌠ BIO╙ call≤ anΣ don'⌠ allo≈á thσ ì
use≥ t∩ inpu⌠ characters.

     Thi≤ i≤ ß shorthanΣ t∩ placinτ thσ 0 contro∞ codσá int∩ ì
the ZEX Control Message Byte.


Inputs: None


Outputs: None


Registers Affected: None


Side Effects: ZEX Control Message Byte is set to 0


Special Error Conditions: None