Program Logic Manual - All about the IBM 1130 Computing System

Significant variables:Symbolic locationD0006D1000D1020+2 LIBF TV entry.Contents/UseIf DISK! was entered by a monitor system program at D1000, this word is used byDISK1 to simulate a LIBF link word. The contents of this word should referencethe simulated LIBF at symbolic location D0060.Monitor system program entry.D1020+4 LIBF TV link word. Contains the address of the first parameter in the callingsequence.D0235+1 Address of the word containing the beginning of the file-protected area of the disk(D0310+1)on the specified drive.D0280+1 Address of a table in COMMA containing the list of defective cylinders of the diskon the referenced drive.D0305+1 Address of the device code to be used corresponding to the referenced drive.(D0330+1)D0350+1 Address of the word in COMMA containing the current position of the heads on the(D0390+1)referenced disk.D0901D1901D1902 andD1903D1904 andD1905D1906 andD1907D1908 andD1909D1911D1912 andD1913D1925D1926D1929D1930D1932D1938$DBSYSector address of previously executed Forced Read.Current arm position obtained by reading the sector address after seeking.Last two words of sector previously read. The area is used to store an intermediateword count and sector address.IOCC for the operation currently being performed.IOCC for the user-requested function.IOCC to reader sector address into D1901 after a seek operation.Second word of Sense IOCC.Used to save and restore the ACC and EXT.Word count remaining to be read or written from originally requested word count.Next sequential sector to be read or written.Non-zero if the seek option was requested.Non-zero if the displacement option was requested.Second word of Seek IOCC.Current sector address.Non-zero indicated routine is busy; this word must be cleared to zero before entryto this routine is permitted.Program Analysis Procedures 179