IBM System/7 Functional Characteristics - All about the IBM 1130 ...

.11.1111111.111 MP I 111.10114P III PP 41011111111110.11RffiliFEENINNAThe Asynchronous Communications Control Attachment (ACCA) is an optional featurethat resides in the IBM 5010 Processor Module Models A and E.The ACCA controls the transfer of serial data to and from a host processor at a remotelocation via a data set and communications line facility. The ACCA can be used forconnecting a System/7 to telecommunication equipment or other processors havingcompatible adapters. Any number of System/7 configurations (each with an ACCA) canfunction as satellite processors to a System/360 (model 25 and larger), a System/370, oran 1800 Data Acquisition and Control System. (For the user who is not familiar withdata communications, the manual Teleprocessing System Summary, Order No. GA24-3090,may be helpful.)Data transmission is serial-by-bit, using the start/stop method of character and bitsynchronization. The code used is the IBM Paper Tape Transmission Code/Extended BinaryCoded Decimal (PTTC/EBCD). (See Appendix D.) Figure 7-1 shows the data word andPTTC/EBCD bit assignments within the second byte of the word. Odd parity must be usedfor bits 9 to 15. Therefore, on transmit, the character parity bit (C-bit) must be providedby the program in the System/7 processor; on receive, the ACCA checks for correct parity.Data rates, selected by machine pluggable options, are 14.8 or 66.7 characters per second.These character rates correspond to bit rates of 134.5 and 600 bits per second respectively.The ACCA operates in half-duplex mode; that is, the System/7 or the host processorcan either transmit or receive data, but cannot transmit and receive simultaneously.0 8 15Data CharacterIII!'IS) B A 4 2 Ct ..—.......--,........—.-Character bitstShift bit Parity check bit0 = lower case for bits B, A,1 = upper case 8, 4, 2, and 1Figure 7-1. ACCA data word