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

111111111111111111i, 11111 II I ITRACK INITIALIZATIONBefore any disk can be used, the surfaces must first be formatted with address marks,sector identifiers, and gaps. A special write command records these fields on a disk surface.Once a disk is formatted, the remaining disk I/O commands can be used. The proceduresrecommended for formatting a disk are described later under "Track InitializationProcedures."Format Track0 5 8 11 16 20 26 31Op code R Fun Zeros Mod DA MA0 0 0 0 1 XXX 00100000 0 1 0 0 * * * * • *XXXXXXi iii II 11 !Il l 1 1 1 1 1 1 1 1 1 1 1 1 1••••■•••,,e•IIM, ••••■•■,■■■■ ••■■•••■••■•■,■••••••,,•■•• .••■••••,•■■••• ■■•••••■••■•••■••0 8-F 2 0 4 0 0-3 XAddress marks, sector identifiers, gaps, and 0's in the data fields are written on a track.(The read/write head used to write the track must be selected by a previous seek commandor load-next-sector-ID command.) Sector identifier data to be written in the first sectoron the track is contained in the index register (R), or the accumulator if R=000. The dataword has the following format:0 2 1011 15FCTS1 1 1 1 1 11 1 1 1S•■■•■••,....111., N.1111.,,,•■••' S•••11...„,••■0The track bit (T) is an extension of the sector address. Thus, sector numbers 0 through23 are written on the upper track and sector numbers 32 through 55 are written on thelower track.The cylinder number field (C) must contain the physical number, in binary, of thecylinder (0000 0000 to 1100 1011). This number is the same for every sector ID on thesame track.The sector number field (S) must be set to 0. This number is incremented automaticallyfor each successive sector formatted on a track.Formatting starts at the first sector past the index mark and continues for 24 sectors. Fora previously unformatted disk, the flag bits (F) in the data word are set to 0. A device-endinterruption request is presented after the track is completely formatted. After the trackhas been formatted, a read verify operation must be performed to check for any surfacedefects on the track. If an error occurs during the verify operation and the track is determinedto be defective, the track must be reformatted as described previously under "Flagging.,Note: The disk storage module gives a busy indication to all other commands while a trackis being formatted.IBM 5022 Disk Storage Module 15-27