Program Logic Manual - All about the IBM 1130 Computing System

2. (if the Telephone sequence is received) setsRTBSY off (zero), turns the line around, andbegins transmission of the IDLE character for1.5 seconds (the Transmit TEL operation iscomplete)3. (if the Telephone sequence is not received)decrements the retry counter by 1 and re-issuesthe initial Start Write to transmit the Telephonesequence4. (if, after 7 attempts to transmit the Telephonesequence, the Telephone sequence is notreceived in response) branches to the user'serror routine5. (on return from the user's error routine) resetsthe retry counter to 7 and re•-issues the initialStart Write to transmit the Telephone sequenceif the accumulator is positive.6. sets RTBSY off (zero), turns the line around,and begins transmission of the IDLE characterfor 1.5 seconds if the accumulator is negative(the Transmit TEL operation is complete)performs a Close operation (see "Close" underCall. Processing, above) if the accumulator iszeroTimeout (Transmit). If a timeout interrupt occurs,the timeout routine1. branches to the read response routine to handlethe timeout as if an invalid response wasreceivedWrite Response (Receive). The write responseroutine(if a data record was received in the lastAcknowledge and Receive operation) transmitsan acknowledgement, including the appropriateacknowledgement character--ACK1 for oddnumbered records, ACK2 for even numberedrecords (if the acknowledge is to be positive);then performs a Start Read (puts the SCA in thereceive mode and causes a read responseinterrupt)(if a data record was received in the lastAcknowledge and Receive operation) transmitsthe Error Received sequence (if the acknowledgementis to be negative); then performs a StartRead(if the End of Transmission sequence has beenreceived) transmits the End of Transmissionsequence; then performs a Start Read4. (if the Telephone sequence has been received)transmits the Telephone sequence; then performsa Start ReadRead Response (Receive). The read response routine1. (after the appropriate acknowledgement has beentransmitted) expects to receive (1) the Start ofRecord sequence, followed by the data record(including ILRCs, if required), followed by theEnd of Record sequence,(2) the End of Transmissionsequence,(3) the Telephone sequence, or(4) the Inquiry sequence2. (while receiving data characters) builds an LRCto check against the ILRC/LRC received3. (if 1 above is received) compares the LRC builtagainst the ILRC/LRC and indicates an error inthe data record if they are not identical4. (if 1 without errors, or 2 above is received) setsRTBSY off (zero), turns the line around, andbegins transmission of the IDLE character for1.5 seconds (the Acknowledge and Receiveoperation is complete)5. (if 3 above is received) branches to the user'serror routine6. (on return from the user's error routine) transmitsthe Telephone sequence; then performsa Start Read (puts the SCA in receive mode andcauses a read response interrupt)7. (if 4 above is received) turns the line around,re-transmits the appropriate acknowledgement;then performs a Start Read8. (if characters other than one of the above--1, 2,3, or 4-- or 1 above, with errors, are received)decrements the retry counter by 1, turns theline around, and transmits the Error Receivedsequence; then performs a Start Read9. (if, after 7 attempts, one of 1, 2, 3, or 4 aboveis not received) branches to the user's errorroutine10. (on return from the user's error routine) resetsthe retry counter to 7 and re-transmits theError Received sequence attempting again toreceive one of 1, 2, 3, or 4 above, if theaccumulator is positive11. sets RTBSY off (zero), turns the line around,and begins transmission of the IDT,E characterfor 1.5 seconds if the accumulator is negative(the Acknowledge and Receive operation iscomplete)12. performs a Close operation (see "Close" underCall Processing, above) if the accumulator iszero13. (if nothing is received in response to the lastacknowledgement transmitted) a timeout occursTimeout (Receive). The timeout routine1. (if nothing is received in response to the lastacknowledgement transmitted) branches to the108.4