2.2 The IBM 7171 ASCII Device Attachment Control Unit - Index of

D.3 Definition of the IBM 7171/User Program InterfaceIn the following definitions, this notation applies:addrCRLFCRbytebyteAn ASCII representation of a 2 byte address, e.g. 1 COO. The digits0-9 (ASCII x' 30' - X' 39') and the letters A-F (ASCII X' 41' -X' 46 ') are legal. All addresses are offset from segment DCOO.The ASCII Carriage Return - Line Feed sequence, i.e. X' ODOA 'The ASCII Carriage Return, i.e. X' OD 'The ASCII representation of any two arbitrary bytes, e.g. 1F43. Thedigits 0-9 (ASCII X' 30' - X' 39') and the letters A-F (ASCII X' 41 '- X' 46 ' ) are legal. In the special case where the 'bytebyte' is theLAST of a 'one or more'(!) sequence, one or two bytes may be used.e.g."S 1COO: 34567890" and "S 1COO: 3456 1432 OA3B 78" areboth legal but "S 1COO: 3456 124325" is NOT legal.chksumA one byte checksum of all data bytes on the line just issued inresponse to dump commands. One line is defined as the data bytesbetween the second colon and the checksum in a DUMP response.The checksum algorithm is given later.One or more of the sequence immediately following the!. Thesequence mayor may not be surrounded by parentheses.Characters between single quotes are literal ASCII characters.D.4 Interface CommandsThe commands are defined as follows:1. Exita. InputTo issue an exit command, enter:( 'E') + (CR)b. OutputThe response is(CR) + ('Ok') + (CR)Followed by the 'ENTER TERMINAL TYPE:' message.D-2 IBM 7171 Reference Manual and Programming Guide