This is a special terminal system designed to meet the requirements of the Video Banking System (VBS). It differs from the "standard" terminal I/O system in:

Option of eight level "ASCII" or EBCDIC translation interfaces

Simple terminal editing (destructive backspace)

Optional terminal input timeouts

Circuit zaps are returned to the program

Higher performance

VBSTIOC(0;SB,M,SIK,SOK,CCK,BWAIT==>(c;SIKVBS,SOKVBS,CCKVBS,TCEMK)
- Creates an instance of the VBS terminal system with eight level "ASCII" support. VBSTIOC is a factory program and uses extended jump protocol {(p3,ejp)} to receive its parameters. SB is a prompt space bank, M is a meter, SIK, SOK and CCK are terminal keys (possibly from the receptionist {(p2,receptionist)}.) and BWAIT is either a BWAIT key or a BWAIT multiplexor key, in which case timeout requests will be honored; or a data key (e.g. DK0), in which case no timeout support will be generated.

C = 0 if terminal system created, c = 1 if SB is not a prompt space bank, c = 2 if SB doesn't have enough space, c = 3 if CCK does not have KT = either X'20E' or KT+1.

VBSTIOC(1;SB,M==>c;DC)
- IF c is zero then DC is the domain creator used by VBSTIOC to create domains. C = 1 or c = 2 are the same as order code 0 above. This is for debugging.

VBSTIOC(2;SB,M,SIK,SOK,CCK,BWAIT==>(c;SIKVBS,SOKVBS,CCKVBS,TCEMK)
- Creates an instance of the VBS terminal system with EBCDIC translation. Otherwise this order code is functionally identical to order code 0.

VBSTIOC(4;SB,M,SIK,SOK,CCK,BWAIT ==> c;SIKVBS,SOKVBS,CCKVBS,TCEMK)
- Creates an instance of the VBS terminal system with ASCII translation and no processing of backspace (fully transparent).

VBSTIOC(5;SB,M,SIK,SOK,CCK,BWAIT ==> c;SIKVBS,SOKVBS,CCKVBS,TCEMK)
- Creates an instance of the VBS terminal system with EBCDIC translation and no processing of backspace.

VBSTIOC(kt==>X'C0E');

This key is a superset of the byte stream producer protocol. The following are the extensions and differences from the protocol defined in {(p3,bytstream)}:
Data passing through SIKVBS is broken up into transmissions {as described in (transmis)} with the exception that SIKVBS produces only data characters. The number of bytes in a transmission is limited to an implementation-defined maximum of 256. It is as if the 256th character were always an activation character. But, if a transmission is ended by reaching the limit, and the echoing status is then changed, some characters may be echoed in error. The data received from SIK is echoed promptly according to the echo mask. If the consumer can accept it, the transmission is always delivered in one packet.

The return code from SIKVBS is used to indicate the ending state of the transmission as follows:

0 - Normal activation

1 - Input transmission exceeds 256 bytes

2 - Timeout expired before activation character received

3 - Error signal received from the network (data loss)

4 - Break signal received from the network

kt+1 - Circuit zapper received (normal byte stream end of file)

Characters from SIK (the circuit) are assumed to be ASCII for the purposes of activation and editing. Either even or odd parity characters will cause the activation or editing behavior. Tymnet control codes {(cc)} are checked for validity and either consumed or provided through the CCKVBS interface.

A (_line) is the largest string of data which is contained in a transmission and does not contain a line ending character. Carriage return is a line ending character. Line feed is a line ending character if and only if, if it were echoed, it would be echoed as LF CR.

The (_prompt string) is typed at the beginning of each line.

{ni}For the purpose of computing tab stops when expanding tab to spaces a transmission is considered to begin at the left margin, regardless of the actual position of the carriage. The prompt is disregarded. Carriage position is computed as if all characters were being echoed. Output from SOKVBS is not considered.

The following characters in the input stream cause editing functions. (This section is not tutorial.)

Control-H
Backs up one character in the input line. Will not back up over a line boundary. Sends <BS><SPACE><BS> to the terminal to erase the character from the CRT.

{ni}Control-I (tab)
If tabs are being expanded to spaces then this character is equivalent to typing enough spaces to go to the next tab stop. The echoing of the spaces is controlled by bit 0 of the echo mask. If tabs are not being expanded to spaces then tab is a data character.

Control-J (linefeed)
Is a line ending character if linefeed is being echoed as LF CR as opposed to LF alone.

Control-M (carriage return)
Is a line ending character.

Known deficiencies:
If you back up {control-H} over tab it loses track of the carriage position, so a subsequent tab being expanded to spaces won't work right.

This key is a byte stream consumer. Bytes are sent directly to SOK (the circuit).

A zapper for the circuit can be signaled by the byte stream protocol EOF convention (N.B. This differs from other terminal system modules). If the producer signals EOF, a zapper is sent after ensuring that characters previously sent have reached the other end of the circuit.

SIKVBS may be producing (reading) at the same time that SOKVBS is consuming (printing). In this case, any output generated as a result of echoing or editing may be interspersed with the output sent to SOKVBS.

CCKVBS(2;==>;) "Send zapper"
Works regardless of backpressure.

CCKVBS(3;==>0;) "Start gobbling"
Turns on a flag called "gobbling".

While gobbling is on, SOKVBS will be prompt. Messages for the circuit (including perhaps echoes) will be discarded beginning at this point in the output stream. However, a character gobbler is never discarded. If gobbling is turned on while SOKVBS is consuming, it returns immediately. Gobbling is initially off.

CCKVBS(4;==>0;SIK,SOK,CCK) "Destroy VBSTIO"
Destroys VBSTIO and signals EOF on SIKVBS and SOKVBS.

If SIKVBS is consuming, SIK is available.

There is no way to determine whether SOK will be available. If a key is not available, DK(0) is returned in that position.

Since no limit for SOK is returned, the user will have to assume a limit of zero initially.

Programming note: See the tap operations on the CCK key for reacquiring full use of the circuit after the destruction of VBSTIO.

CCKVBS(5;tabtable;==>c;) "Set tab stops"
Tabtable is a string of up to 256 bits {32 bytes}. There will be a tab stop in column i if the i'th bit is a one. If tabtable is shorter than 32 bytes it is padded with bytes of value hex 80 {specifying a tab stop every 8 columns}.

If there is a transmission in progress, C=1 and the tab stops are not changed. C=0 if ok.

CCKVBS(6;==>;) "Activate now"
This operation has its effect at some instant between the jump to CCKVBS and its return. The effect is: if SIKVBS is producing, it promptly stops producing and returns whatever data it may have. If SIKVBS is not producing, then the next time it becomes producing it will return promptly.

"Activate now" ends a transmission if the echo mask was zero.

CCKVBS(7;==>0;) "Stop gobbling"
Turns off "gobbling".

CCKVBS(8;==>c;) "Echo CR as CRLF"
If there is a transmission in progress, c is 1. Otherwise c is zero and when CR is being echoed, it is echoed as carriage return, linefeed.

CCKVBS(9;==>c;) "Echo CR as CR"
If there is a transmission in progress, c is 1, otherwise c is zero.

CCKVBS(10;==>c;) "Echo LF as LFCR"
If there is a transmission in progress, c is 1, otherwise c is zero.

CCKVBS(11;==>c;) "Echo LF as LF"
If there is a transmission in progress, c is 1, otherwise c is zero.

{ni}CCKVBS(12;==>c;) "Expand tab to spaces"
If there is a transmission in progress, c is 1. Otherwise c is zero and tab on input is treated as an abbreviation for enough spaces to go to the next tab stop. (N.B. Appears to the caller to be implemented except tab characters will continue to appear in the input stream.)

CCKVBS(13;==>c;) "Don't expand tab to spaces"
If there is a transmission in progress, c is 1. Otherwise c is zero and tab is treated as any other character.

CCKVBS(14;==>c;) "Send character gobbler"
If there is a transmission in progress, c is 1. Otherwise c is zero and a character gobbler is sent to the circuit. Sending a gobbler does not affect the state of echoing or tab stops. It may cause terminal characteristics to not be set, and may gobble a hang character. It does gobble echoes.

CCKVBS(16+4n+2d+b;==>c;) "Filter characters"
N, d, and b are either 0 or 1.

If there is a transmission in progress, c is 1. Otherwise c is zero and three flags are set.

If n=1, NUL in the input stream will be ignored.

If d=1, DEL in the input stream will be ignored.

B is included for compatibility with CCK2 thru CCK6. Its value is either 1 or 0 and is ignored.

CCKVBS(24,ps;==>c;) "Set prompt string"
Ps may have up to 8 characters; if it has more, or there is a transmission in progress, c is 1, otherwise c is zero and the prompt string is set to ps. The string is taken to be eight level ASCII or EBCDIC depending on which translation version was built (VBSTIOC oc=0 or oc=2).

CCKVBS(25,ol;==>c;) "Set old line"
This is included for compatibility with CCK5 and CCK6. If a transmission is in progress then c is 1. Otherwise c is 0

CCKVBS(26;==>c;) "Pseudoactivate"
If there is a transmission in progress or another "pseudoactivate" since the last transmission ended c is 1. If a pseudoactivate cannot be honored due to the implementation-defined maximum limit on the number of bytes in a transmission, c is 2. Otherwise, c is 0 and SIKVBS behaves as though none of the characters in the previous transmission was an activation character and the transmission did not occur. The data will be transmitted again (after perhaps being subjected to editing).

CCKVBS(32,(4,time);==>c;) "Set activation timeout"
Sets a timeout for activation. This will reset any CCKVBS 33 time to zero. If VBSTIOC was called with a data key instead of a BWAIT key, or the time value specified is greater than 31536000 (365 days), or the length of time is not 4 then c is 1 otherwise c is zero. Time is in unsigned binary seconds and if it is zero there is no timeout. If time seconds elapse from the time SIKVBS is called with no activation characters from the circuit then SIKVBS will return with return code 2.

CCKVBS(33,(4,time);==>c;) "Set elapsed timeout"
Sets an elapsed timeout. This will reset any CCKVBS 32 timeout. If VBSTIOC was called with a data key instead of a BWAIT key, or the time value specified is greater than 31536000 (365 days), or the length of time is not 4 then c is 1 otherwise c is zero. Time is in unsigned binary seconds and if it is zero there is no timeout. C is zero. If SIKVBS is active after time seconds have elapsed then SIKVBS will return with return code 2. To read more characters from the circuit CCKVBS 32 or 33 must be re-issued.

CCKVBS(256+a;==>c;) "Set ASM"
If there is a transmission in progress, c is 1. Otherwise c is 0 and the activation set mask is set to a, where a is less than 256.

CCKVBS(512+b;==>c;) "Set echo mask"
If there is a transmission in progress, c is 1. Otherwise, the echo mask is set to b, where b is less than 256. An input character is echoed if it is in mask set i and bit i of the echo mask is on. See (p2,maskset) for the definition of mask sets.
Examples:
To echo everything except non-printing control characters, set the echo mask to X'F7'.

To echo nothing, set the echo mask to zero.

CCKVBS(kt;==>X'B0E';)