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

The head bit (H) selects the read/write head to be used for the selected disk. H=0 selectsthe upper head; H = 1 selects the lower head.Once a sector ID has been read and checked for the correct ID check character, an interruptionrequest is presented to the processor module. The sector ID must then be readby a read-sector-ID command, described next, in order to obtain the ID just loaded.Note: The load-next-sector-ID command and the seek command are the only commandsthat select a disk and/or a read/write head for a subsequent read or write command.Read Sector ID0 5 8 11 16 20 26 31Op codeRFunZerosMod0 0 0 0 1 XXX 0 1 0 0 0 0 0 0 0 0 1 0 XXXXXXI t!! i i II 1111 III 111111 1 1 1 1••■••••■•••••■•••••°••■•■••,...111w,0 8-F 4 0 2 0 0-3 XThis command transfers a 16-bit sector identifier into an index register (R), or the accumulatorif R=000. The read-sector-ID command must be preceded by a load-next-sector-IDcommand, described previously. The 16-bit identification word transferred to the registerhas the following format:0 2 1011 15DAMAF C T S11111 1 1 1111S*****„....**,X X X XNo interruption requests result from the execution of this command.Read Verify0 5 8 11 16 20 26 31Op code Fun Zeros Mod DA MA0 0 0 0 1 XXX 0 0 1 0 0 0 0 0 0 1 0 1 XXXXXX1,111 I 1111 1 1 1 1 1 1 1 1 1 1••■••••se.m." •■•••••.,,••■■ ••■■•■•,,■•••• ••■••■„,....••■•• i*•11.*,..•11•, ■•■••*,,,MANI0 8-F 2 0 5 0 0-3 XThis command reads and verifies the entire data field and its corresponding check characterin a sector specified by the control information word contained in the index register(R), or the accumulator if R=000. The contents of the register have the following format:0 2 1011 15F C T S1111111 1 111••■•■■•••••••/IBM 5022 Disk Storage Module 15-17