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- _______________________________________________________________________________
-
-
- ItaPac - A Brief Introduction
-
- A Telecom Computer Security Bulletin File
- _______________________________________________________________________________
-
-
-
- Prologue
- --------
- This text will represent a very complete tutorial about a packet switching
- network used in Italy: ItaPac. The purpose of this file is to supply very
- interesting information to have secure use and VERY LONG ItaPac password
- lifetime. It includes also a brief summary of what (shit) ItaPac is, techincal
- terms, various news.
-
-
- What's ItaPac
- -------------
- ItaPac is the Italian Packet Switched Network. The "packet" protocol is called
- as it is because the data which travels through the network is assembled in
- 255 char groups (packets), with an address physically in the net towards which
- data is sent at fixed time intervals. Packets can thus contain different
- source data, and in this way they divide the cost of transmission and optimize
- net traffic. All of which runs transparent to the users, which doesn't remark
- of commutation, and works in an apparent "real time".
-
- In order to support all available protocols, the Packet Switch needs gestional
- software. As for definition, all terminals able to support the switching are
- called PADs (packet assembly-disassembly) and work following the CCITT X.25
- recommendations.
-
- A PAD is very expensive to run. It is not the software or hardware that is so
- expensive, but rather the continuous maintenance and supervision required to
- keep the system running. Normally, most of the users prefer have the switching
- handled by an ACP Server which makes his call and transforms the packet proto-
- col from X.25 to an X.28 asycronous, that is compatable with the normal modems
- that we use.
-
- The user becomes like a DTE (Data Terminal Equipment), he connects to an ACP
- (Adapter/Concentretor of Packets) and can operate in trasparency without
- any kind of problems.
-
- The user can login to a pad in either of two ways:
-
- 1) DIRECTLY: by dedicated wire installed by Italcable. The cost is higher,
- but that guarantees a much higher transmission quality.
-
- 2) SWITCHED: by phone (switched line, not to be confused with ACP, even if
- there are similarities); the cost is much lower, but the transmission
- quality is unacceptable at times.
-
- The direct X.28 user has his own network user address (NUA). Some users have
- only one NUA while others have a multiplexed system. This system generally
- consists of one NUA and a variable number of subaddresses. The actual number
- of subaddresses depends on the number of doors he has into his pad.
-
- The switched user (poor) can only call others DTE, but he cannot receive calls,
- because he doesn't a network user address. In effect the only address where he
- can answer is that of the PAD on which he is logged on. Thus the DTE call from
- a phone number (of home, office, etc), if he can receive calls from another
- DTE, means that the hardware is able to scan the call, and we will all be in
- the shit (sorry for the hard expression).
-
- Taking apart the quality in trasmission, there is no difference between the two
- X.28 types: both need a modem. The first, connected to a standard phone line,
- and the second to dedicated one.
-
- For the rest of this file we will talk about the X.28 terminals of the second
- type: the dedicated ItaPac PADs.
-
- The ACP at their time, are connected to NCP (Nodes of Commutation of Packets)
- with transit functions or access for DTE X.25 and of local commutation. The
- NCP are connected between them at high speed (64k/second), and ACP are conn-
- ected to NCP at 9600 bit/second.
-
- ___________________________________________________________________________
- | | | | | |
- | User Class | Xmit Methods | Speeds | Protocols | Access Methods |
- |______________|________________|__________|_____________|__________________|
- | | | | | |
- | Char by Char | Start/Stop | 300/1200 | X28 | Via Phone or |
- | Terminal | Full/Half Dup. | baud | | Direct |
- |______________|________________|__________|_____________|__________________|
- | | | | | |
- | Packet | HDLC | 2400 and | X25 | Direct |
- | Terminals | Full Duplex | 9600 bps | | Only |
- |______________|________________|__________|_____________|__________________|
-
-
- The CCITT standard makes it possible to interface ItaPac with other networks
- around the world. In effect, the NCPs are connected as big telephonic centers.
- Anyway, it seems that all European traffic to the USA and other countries, such
- as Australia, Argentina, Japan, etc, will transmit by the centers that are in
- Paris, France. Maybe from Paris data is sent via satellite, but I don't know.
-
-
- NUIs, NUAs, and DNICs
- ---------------------
- Well, when you connect to one of ItaPac's entry points (of which there are 41
- ACP sites on Italian terrain at 300/200 baud and full duplex (V21, V22)),
- ItaPac responds:
-
- ACP:** I T A P A C ** GENOVA 32 PORTA: 4
-
- The above is an example of the herald for an entry node in Genoa. In the
- example you can note that the number "32:" is really the node (the phone number
- you have called). Larger cities generally have more than one node. The PORTA
- is the port to the node (the physical entry point to the node). "PORTA: 4"
- means that you are connected to the fourth port of this particular Genoa
- ItaPac node.
- You can also see from the above example that there are 3 other people connected
- to the same node as you. Every ItaPac node can support at greatest a finite
- number of ports. If all the ports of a node are in use then the PAD will
- reject all new DTE calls.
-
- Frequently most (or all) of the ports until Friday night will not answer at
- all. Until one logs you off you cannot enter a port that is in use. Very
- often the first 2 or 3 ports will be busy from an internal console, or these
- will be reserved as an "emergency lane" for internal-use-only. A good way to
- use a free door is to send to people that are probably the callers an Urgent
- Call Income (UCI; in the States it is known as a BVC -- Busy Verification
- Signal -- AKA emergency interrupt). The you can redial the node. This time
- ItaPac will answer. The message "Beware, please, Urgent Urban Call Incoming"
- will appear on the screen. This will blow our friend from the port, thus
- freeing it for our use. Eh eh. Now for some definitions.
-
- 1) NUI
- 2) NUA
- 3) CUG (optional)
-
- NUI - Network User Identification: Nothing other than an ItaPac password.
- Every time you call an NUA, ItaPac will charge the account of owner of the
- password. Often NUIs are valid only for certain nodes. That is if the
- contract signed with Italcable will allow a 300 baud at Genova on 2697, this
- NUI will not work on the 2564 node. SYNTAX: the NUI must be preceded by
- UPPERCASE "N" and finished by a minus "-". The NUI MUST BE TYPED IN UPPERCASE.
- Between "N" and "-" the NUI will not be displayed (echoed). You will obtain
- only "N-" on display.
-
- NUA-Network User Address: the physical address of a remote DTE. Similar to a
- phone number, you understand. Must be typed without blank inside and soon
- after the NUI (or a timeout will occur and ItaPac will hang up on you).
-
- CUG - Close User Group: this is basically a high-security NUI. CUG stands for
- Close User Group. CUG users have access to optional parameters that are used
- for user recognition (and you know what that means). Having a CUG account is
- very handy. CUG users have the ability to inibit hackers (after all, they are
- there for network security, right?). There are less CUG users in Italy than
- the USA and are generally rare (but I know of one). A typical example would
- be the US Tymnet NUAs (03106nnnnnn). The PAS response will be ACP:CLR NA or
- Call Not Accepted and shut down. Makes hacking on a CUG account a good way to
- waste your time.
-
- Now we will take a closer look at an ItaPac NUAs structure (the numbers are
- examples only):
-
- DCC NC
- | __|
- / \|
- 12345678901234
- \_ /
- |
- DNIC
-
- DNIC = Data Network Identification Code; it contains the address of the country
- to be called and the code for the network chosen. It is then divided into two
- parts: DCC and NC.
-
- DCC is the Data Country Code; a three digit number that is the phone prefix.
- Every country has different one.
-
- NC is the Network Code; a country can have more than one data network. In
- Italy there is ONLY packet switched network, the code is "2" and it is Dardo.
-
- Follow with: the prefix of the called city, the DTE number, an eventual suffix
- that is the "phone particular" (max 4 digit).
-
- Note: The DCC is used only to call outside. DCC must be preceded by a zero.
- ItaPac, in this case, is different from other countries.
-
- Let's show a pratical example: The Cilea of Milan (Segrate).
-
- The NUA is: 2220208
- |||______ local address of DTE
- ||_______ 2 (02) = Milano
- |________ NC: 2 = ItaPac
-
- Now, another example: the Altos Unix (altger) in Munich, West Germany (note:
- a favorite hangout of Xtension).
-
- The NUA is: 026245890040004
- |\ /|\_ _/|
- | | | | |____ 40004: network address
- | | | |_______ 5 8900: munich prefix
- | | |__________ 4: DATEX-P (germany ItaPac)
- | |____________ 262: DCC West Germany
- |______________ foreign call
-
- The NUA's structure isn't so all the time. NUAs can exist that don't appear to
- have countries or cities. This because the address is sent to an indicated ACP
- that will provide the rerouting of the call. If the NCP has been instructed to
- consider a certain address like another, the DTE can have a Rome NUA and be
- located in Genoa. As call with the account to called...
-
- It's very important to be able to read an NUA. Many times you can find systems
- like VAXs and UNIXs and some refer to not-interactive logins; NUAs are not
- often completed. An NUA without a DNIC is like a phone number without an area
- code: its meaning is nothing. Usually the system makes references to a subject
- network, or it supplies other info in a less clear fashion. At this need I
- will supply a very short list of world wide DNICs I've found (notice that they
- are old hat, the new stuff is only for friends)...
-
- Beware: many countries own more than one national network (GB, USA, etc) then
- you will probably hear a thousand cries of "In USA where? On Tymnet, or
- Autonet? or Telenet? or RCA? EtherNet?" And I can continue...
-
-
- DNIC Network Name Country
- _______________________________________________________________________________
-
-
- 2041 Datanet 1 Netherlands
- 2062 DCS Belgium
- 2080 Transpac France
- 2284 Telepac Switzerland
- 2322 Datex-P Austria
- 2329 Radaus Austria
- 2342 PSS UK
- 2382 Datapak Denmark
- 2402 Datapak Sweden
- 2405 Telepak Sweden
- 2442 Finpak Finland
- 2624 Datex-P West Germany
- 2704 Luxpac Luxembourg
- 2724 Eirpak Ireland
- 3020 Datapac Canada
- 3028 Infogram Canada
- 3103 ITT/UDTS USA
- 3106 Tymnet USA
- 3110 Telenet USA
- 3340 Telepac Mexico
- 3400 UDTS-Curacau Curacau
- 4251 Isranet Israel
- 4401 DDX-P Japan
- 4408 Venus-P Japan
- 4501 Dacom-Net South Korea
- 4542 Intelpak Singapore
- 5052 Austpac Australia
- 5053 Midas Australia
- 5252 Telepac Hong Kong
- 5301 Pacnet New Zealand
- 6550 Saponet South Africa
- 7240 Interdata Brazil
- 7241 Renpac Brazil
- 9000 Dialnet USA
- 7421 Dompac French Guiana
-
-
- This list may be in the hands of hackers everywhere. And, because the bread
- for a hacker is done with ItaPac's floor, the minimum I suggest is to learn by
- memory the main International DNICs. Not these for French Guiana, but the main
- European and American ones.
-
- Let's return to ItaPac. When you are connected to a remote system, the network
- sends an ACP: COM and it leaves the field and lets you join the host. To clear
- call and return in command mode (the star "*" prompt) must make some
- differences.
-
- 1 - for the most part, the host leaves the possibility to user to talk with his
- PAD, either to setup his parameters, close, reset or confirm the call. In
- this case, often frequently, with the sequence CTRL-P ItaPac will reappear
- with its "*" prompt and it accepts commands. Typing "CLR" ItaPac will
- close the virtual call to host and answer "ACP: CLR CONF".
-
- 2 - Some Hosts, usually those with internal PADs, won't allow to ItaPac control
- to the user. CTRL-P is not recognized, and the only way to logoff or catch
- the control of the PAD is send a ten LONG-BREAK sequences. The BREAK, not
- to be confused with CTRL-C, that is not in this site, is an INTERNAL signal
- whic(BFs not an ASCII code. It is used by the communication program you
- use to send that acknowledgment. If you don't have the capability to send
- BREAK (short or long); beware not to use these black holes from where the
- only way to exit will be the physical disconnect from the PAD (ie, drop
- carrier on the modem).
-
- 3 - The use of CLR is not correct and in most cases it will cause serious
- problems to host machines. In effect, their software (or perhaps hardware)
- is not able to translate correctly the loss of carrier and enters into a
- "Wait-State Pending", that will finish only before a well-defined interval.
- In the mean time, this door is unavailable. Network administratons never
- like CTRL-P CLR.
-
-
- Network Signals, Profiles (Outline, Shapes, Sketch), Parameters
- ---------------------------------------------------------------
- A detailed description about all net signals, standard outlines and parameter
- sets, is supplied from a "manual about ItaPac access from X28 start-stop
- terminals"
-
- This manual can easily be "thieved" at kermesses in Italcables stands, in more
- desperate cases, you can ask that to your friends.
-
- What is not written therein into from Italcable is the meaning about parameters
- 14,15,16,17,18,19. Official guide stops at the 13th. But command ^P PAR?
- gives a full list with 19 entries! Now here are the descriptions:
-
- 14: Padding after Line feed (LF)
- 0 No padding inserted
- 1-15 When it is in the Data Transfer state, the pad inserts a time delay from
- 1 to 15 chars times the length after each LF that it inserts. The
- normal setting is determined by the terminal in use.
-
- 15: Editing of data
- This parameter and the following parameters (16, 17, and 18) determines
- how editing of data is perfomed when the pad is in the Data Transfer
- State
- 0 editing of data is not possible
- 1 Must be set to this value if the editing facility required
-
- 16: Charachter delete character
- 0 characted deletion is not possible
- 1-255 This is the IA5 decimal code of the choosen delete character. The
- normal setting is 127 (for RUBOUT or DEL)
-
- 17: Buffer delete character
- 0 Buffer deletion is not possible
- 1-255 This is IA5 decimal code of the choosen buffer delete char. The normal
- setting is 24 (CTRL-X) or (CAN)
-
- 18: Buffer display character
- 0 Buffer display is not possible
- 1-255 This is the IA5 decimal code of the choosen buffer display char. The
- normal setting is 18 (CTRL-R) or (TAPE-ON)
-
- Parameter 19 is unknown. One word about Delete. It's possible to correct what
- is typed in command mode via the DEL key. If you use the Backspace (ASCII 8)
- key ItaPac will not accept corrections but it will translate these as true
- chars.
-
-
- PAD SPEED
- ---------
- If your modem will colloquiate with a PAD at a defined baud rate (300 or 1200,
- full duplex) the packet transmission will slow in a drastic way the number of
- incoming and outgoing characters from your DTE.
-
- PADs send a continuous stream of clear-to-send and Ready-to-send signals that
- are really macro rests between packets. At lower transmission speeds (ie, 300
- baud) the switching does not feel right, but at 1200 it does. We have computed
- that the speed of real transfers and receiving can, at maximum performance,
- raise to 450 baud. It is slower when you transfer a file, when the PADs work
- is very heavy. Via Xmodem, the PAD will try to destroy time-out signals, or
- confuse all. Public computer systems such as Delphi know that also. If you
- aren't able to download correctly using the Xmodem protocol then that means
- that only the remote host isn't detecting the differences between packets
- and asybchronous terminals.
-
- The question is: will it happen only on ItaPac (not new) or is a common
- problem to all NCPs?
-
-
- "NC" Nights
- -----------
- There are nights in which every address you call is "NC". The Network Conges-
- tion state is very frequent on ItaPac, and will disallow the use of the network
- used from NCP. The causes are very mysterious. At night Firms aren't using
- ItaPac, and it seems the network is used only by hobbists. Then what? At the
- Service center they negate all, but this is reality. ItaPac, at the end, is an
- asshole.
-
- It has very high rates but they will add a joke to the classical thief: some-
- times it doesn't work. How does it not work? Ha! To them everything is
- always ok. And then someone will cry scandal if you try to bypass them!
-
-
- NUIs USED
- ---------
- Usually, NUIs that are used (or had been used) are demo NUIs. It hasn't an
- account, and then -in theory- cannot exaust. Operators cannot ever notify
- their use, because they don't have a record of calls...If a demo NUI will die,
- the cause can be one of only two:
-
- 1) ItaPac has changed codes due to normal administration
-
- 2) ItaPac was warning about the happening, or from their techician who had
- noted abnormal traffic and has controlled, or from an external (a son of
- a bitch spy!)
-
-
- +2-15-87
- +-+
- | |
- +--+ +--+
- +--+ +--+
- | |
- | |
- |_|
- 53ST6R
-
-
- An historical NUA- it has been working for over 2 years, and for a SPY...
-
-
- HOW GET AN NUI
- --------------
- The more simple and safe method is to copy that from kermesses where Italcable,
- or otherwise, use X.28 wires. The dedicated X28 DOESN'T NEED AN NUI because
- they are directly connected.
-
- Go near the operator and ask "That is a MODEM?"
-
- Operator (if they have the time) will be moved to pity, in front of so much
- ingnorance, and he feels so relaxed, types in his pw. You, with an optimum
- eye, must read the keyboard and memorize the NUI. This is called shoulder
- surfing.
-
- It is well, in the case of big kermesses, to try to catch ANY booklet, agenda,
- block notes left near terminals. If the stand is owned by Italcable, ALL you
- can catch, must BE, without differences.
-
- A new scanning technique, based on trying statistically calculated, is in exam
- between DTE222. This technique may guarantee, if applied to a long scan time,
- posithives results in NUI research. The minimum number of NUI tried cannot be
- less than to 100,000 (1 hundred thousand), causing cost and time problems.
-
- At large lines, that rule is like: a NUI generator will provide to create a
- very likely NUI following the same criteria. A scanner will try all in an
- automatic manner. It tries 8, then it uses a valid NUI to connect to 22000
- (Echo pad), immediatly it logs off (CLR CONF), putting zero thanks to ACP:COM
- the ACP:ERR ILL counter (how we know, to 10th ERR ILL the pad will logoff
- physical call [hangs]). The 9th try is as security margin. Then the scanning
- will restart. At 1200 baud - therefore - we had a 1400 hours tested NUI
- average. This, is all talk! In addition, it seems that before 700 ERR ILL,
- not looking counter reset, ItaPac will hang up. That will make it more diff-
- icult for our computer; it araises at times (will redial number) and make the
- search more expensive.
-
-
- NETWORK SIGNALS
- ---------------
- Net can send several mesages:
- - as answer to a command
- - for his own decision
- - following an action performed byt remote terminal
-
- 1. Errors messages
-
- ERR CNA syntax of command is correct, but not allowed in this state
- ERR ILL command is not syntactically correct or the hit is not recognized
- ERR EXP timeout and command was not completed
- ERR PNA the requested outline is not assigned yet
-
- 2. Logoff messages
-
- CLR OCC the called number is busy
- CLR NC Network congestion or temporaly failure of hardaware cannot allow new
- calls
- CLR INV Requested performance is not valid
- CLR NA The calling number cannot have connection to DTE (ex: Close User
- Group not compatable)
- CLR ERR Call is hung for a local procedure error
- CLR RPE Call is hung for a remote DTE error
- CLR NP Called NUA is not assigned
- CLR DER Called NUA is out of order
- CLR PAD PAD has hung the call because he had received am invitation to
- "clear" from DTE
- CLR DTE Remote DTE hung call
- CLR RNA Remote DTE cannot accept charged calls
-
- 3. Reset Messages
-
- RESET DTE Remote has resetted virtual circuit
- RESET RPE Call is putt in reset state for remote DTE error
- RESET ERR Call is reset for a local error
- RESET NC Call is hung for a network congestion
-
-
- RATES AND DUTIES
- ----------------
- For whoever wants to subscribe ItaPac, here are the rates. For whoever uses it
- as Portoguese it might be interesting to have an idea about how much it costs
- the real owner of an NUI. The, if you have one, don't abuse and don't tell it
- to the four winds. Remember that real owner can, at any moment, change it!
-
-
- BY X.28 Switched Phone
- ----------------------
- Class (baud) Lire/Month
- 300 12,150
- 1200 7,100
-
- NUI duties: 7,200 / month
-
- to these must be added:
-
- modem duties
- mail and telegraph duties
- contributions and trafic (counter turns!)
-
- The amount of the first two isn't clearly specified on the rates-sheets, but it
- is marked as:
-
- Following the current rates. Last, is so divided: they will consider the
- distance betweenyouser site and the centre of relhative area phone code.
-
-
- X.25-X.28 Direct Connection
- ---------------------------
- Class (baud) Lire/Month
- 300 108,000
- 1200 139,500
- 2400 208,800
- 4800 275,400
- 9600 311,400
-
- To these must be added:
-
- modem duties
- duties foryouse of area to area circuitery
- duties for new wires
-
-
- Time rates for Ports Taken
- --------------------------
- class (baud) Lire/Minute (or fract)
- 300 13.50
- 1200 18.00
-
-
- Time Rates
- ----------
- 6.80 Lire/minute or fraction
-
-
- Volume rates
- ------------
- 1.78 Lire/segment or fraction thereof (1 segment= 64 octets)
-
-
- Rates to call
- -------------
- 30 lire / call
-
-
- Addings per NUI
- ---------------
- 7,200 / month
-
- For time and volume rates there is a 30% discount from 9 PM to 8 AM every day,
- including Saturday and non-working days
-
-
- PVC Rates
- ---------
- 54,000 Lire / Month
-
-
- Class of Max Charge of line
- ---------------------------
- 9,000 * KB / Month
-
-
- CUG
- ---
- Master 56,700 Lire / Month
- Users 900 Lire / Month
-
-
- Payment to Called
- -----------------
- 8,100 / Month
-
-
- Change Options Parms
- --------------------
- 45,000 Lire
-
-
- Speed Class Change
- ------------------
- 90,000 lire
-
-
- Calls List
- ----------
- Lire 30 each voice in list
-
- International Trafic [The rates are in Gold Francs (GF)]
-
-
- Europe
- ------
- GF 0.107 / min or fraction thereof
-
-
- Extra Europe
- ------------
- GF 0.3333 / min or fract (1)
- GF 0.4 / min or fract (2)
- GF 0.5 / min or fract (3)
-
- (1) North America or Middle East directly connected to Italy
- (2) Other countries out from Europe directly connected to Italy
- (3) All others
-
- In a few words, if you aren't a Multinational Company, but an hobbist, you must
- charge a 20 years money loan to be able to afford ItaPac.
-
- The Network is also able to receive characters following international Alphabet
- from CCITT No. 5 (IA5) with 1 or 2 stop bits and it will produce even chars
- with the #2 stop bit. In the exchange of control chars between terminals and
- net, ItaPac will translate characters dropping out the parity and send chars
- with even parity. Characters are exchanged in transparent way to user regard-
- ing parity and bits.
-
-
- TO CONNECT VIA THE SWITCHED WAY
- -------------------------------
- 1) Dial the ItaPac node phone number. Whoever doesn't have an automatic modem
- must switch to data within 10 seconds from the first ItaPac tone.
-
- 2) send two <CR> to build the phisycal connection (within 30 seconds)
-
- 3) ItaPac will send the network herald, ACP identification and entry port (as
- explained)
-
- 4) At you're request: enter the virtual call state by typing ACP: FREE
-
- 5) send call request by issuing the NUI, the NUA and the data field (max 12
- characters optional). E.g: if the NUI is AAAAAA and the NUA is 2345678 you
- must type: NAAAAAA-2345678 <CR>. The NUI is never echoed on screen. All
- sequences must blank free and entered within 120 seconds from first keypress.
- If you type a wrong NUI, net will answer ACP: ERR ILL. If you also need to
- send a data string, (e.g. ABCD) send: NAAAAAA-2345678 D or P ABCD <CR>.
- Typing 'D' before string the following data will be echoed, with 'P'.
-
- 6) net give ACP: COM if call is done.
-
- From this moment starts the data exchange phase and, until you disconnect, all
- commands to the net must be preceded with the ^P sequence. If the call is not
- correct, the net will answer by sending a disconnect signal to specify the
- cause of it. After 10 times of unsuccessfully placed calls, the net will hang
- up the carrier. If the call is possible, the NUA will receive an ACP: (caller
- address) COM.
-
-
- COMMANDS
- --------
- The following commands can be issued prior to having a connection, meanwhile
- data transfer. In the last case, type a ^P before to exit data session (either
- it's considered as data itself). At end of command send <CR>. Beware that in
- a start-stop terminals calls (X.28) commands must sent also from TH in packet
- way, following X.29 procedures.
-
- 1) Virtual call state request:
- STAT <CR>
- will answer:
- - if call is on : ACP: ENGAGED
- - if call is off : ACP: FREE
-
- 2) Shape Choose
-
- PROF <CR>
- network will put on that (see later). At start the #3 is default outline.
-
- 3) Commands to send only during the data exchange (preceded by ^P)
- reset request: ^P RESET <CR>
- That command will cancel call followings data on line.
-
- 4) Interrupt send to remote DTE:
- ^P INT <CR>
- This packet will go over travelling data. Then, the action taked by host
- is software depending on.
-
-
- THE EDITING FEATURE.
-
- By the Editing Feature, you can delete a char or a line to make editing the PAD
- provide buffered characters. The editing function is ever in use during X.28
- and the ACP xmit. To have it meanwhile data transfer you must choose parm 15.
- In this case, the user can choose between parms 16,17 and 18 the usable chars
- to request editing function and he can, via par 19, editing signals send by
- PAD.
-
- 1) Delete a char
-
- To make the deletion of the last type character you must send parm 16 defines
- the character (default DEL) before receving this char, the PAD will erase last
- character in the editing buffer, and, if parm 16 is different from 0, it send
- the signal about the erased char as said from par 19:
-
- if parm 19 is set to 0, no signal sent
- if parm 19 is set to 1, pad sent IA5 signal; this procedure is suggested
- for printer like terminals
- If parm 19 is set to 2, pad will sent a BS SP BS sequence of IA5. This
- procedure will locate cursor at inserting point of new char and is
- therefore suggested for video terminals.
-
- 2) Erase a line
-
- To erase a line you must send the char set into parm 17 (def: CAN). Before
- receving this character, the PAD will erase the buffer and, if parm 6 is set
- to anything save 0, it will send the line deletion character, following par-
- ameter 19:
-
- if parm 19 is set to 0 : nothing sent
- if parm 19 is set to 1 : pad send XXX
- if parm 19 is set to 2 : pad will send SP BS SP of IA5 for a number times
- as the number of chars in the buffer
-
- 3) Display a line
-
- To obtain a line display you must send char defined by parm 12 (def: DC2).
- Before receive this char pad will sent to terminal all chars stored in the
- buffer.
-
- _______________________________________________________________________________
- Downloaded From P-80 Systems 304-744-2253
-