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

cmomill111111•1=101.11=111111111BINARY DATA MODEBinary, data can be received by the ACCA if it is in receive mode and a special sequence oftwo consecutive downshift characters precedes the binary data received in the message(see Figure 7-5). Following this sequence, binary data is received from the host by transferringfour binary bits from each character to create one hexadecimal character.Character bit positions, B, A, 4, and 2 are the four bit positions used for a hexadecimalcharacter. The ACCA assembles four hexadecimal characters, inserting the first characterinto bits 12 to 15, and transfers the resulting 4-character word (16 bits) to the System/7processor storage. The fourth character assembled must have character bit position 1 seton to signal the ACCA that a 16-bit word is ready to be transferred to the processor. Ifa 1-bit is not detected, the ACCA continues converting characters to binary data,overlaying the previously assembled data word.If a bit is received in character bit position 1 before four characters have beenassembled, the ACCA stops assembling characters, fills the remaining high-order bits with0's to complete the 16-bit word, and then presents an interruption request to the System/7.The host system and the ACCA communicate in a normal manner, observing all the rulesfor line control, error checking, and other character constraints. The ACCA exits frombinary data mode when it receives an end-of-block (EOB) or end-of-transmission (EOT)character.Sequence usedwith station controloption onlyEOT SOAHost ©O$EOA Normal Binary EOB Binary EOB EOTdata DS DS data 0 LRC DS DS data CILRC ®0W V1Text Text TextVVSystem/70 4 OYAK YAK YAKNotes:'Bits 8-15 of the index register or accumulator2 ACCA in binary data mode3 Bits 0-15 of the index register or accumulator4 ACCA in standby mode5 ACCA in receive mode'AddressFigure 7-5. Binary data mode operationC) 4Asynchronous Communications Control Attachment 7-13