mancuso@psuvax.UUCP (Pat Mancuso) (04/04/84)
This article contains information about the monitor supplied with the Xerox 820 board. The Jump table has more entries in it than the manual lets on. I have figured out what some of the 'undocumented' ones do, but the explanations that I have given may not show *all* of the features/ramifications of the functions. There are 2 major jump tables in the monitor, one which contains the low-level operations (F000-F042) and one that contains jumps to the higher level operations (F7FD-F805). The manual (from BG Micro) only mentions the first 14 entries in the first table. Monitor Jump Table: Low-level Operations ADDR Name Function ---- ---- ----------------------------------------------------- F000 INIT Cold start entry In : none Out: Does not return F003 PROMPT Warm start entry In : none Out: Does not return F006 CONST Console status test In : none Out: Status in A, FF if char avail, 00 otherwise F009 CONIN Console input In : none Out: Character in A (loop until char avail) F00C CRTOUT Memory-mapped CRT output F00F CRTOUT " " " " In : Character in A Out: none F012 SIOST SIO Port B status test In : none Out: Status in A, FF if char avail, 00 otherwise F015 SIOIN SIO Port B input In : none Out: Character in A (loop until char avail) F018 SIOOUT SIO Port B output In : Character in A Out: none F01B SELECT Disk drive select In : Unit number in C (if drive not ready, keep present one) Out: Status in A F01E HOME Restore to track 0 In : none Out: Status in A F021 SEEK Seek track In : Track number in C Out: Status in A F024 READ Read sector into memory In : Sector number in C, Buffer pointer in HL Out: Status in A F027 WRITE Write sector from memory In : Sector number in C, Buffer pointer in HL Out: Status in A (The following jumps are not listed in the manual--info may not be complete) F02A DUMP Dump memory to screen In : ?? Out: ?? F02D HOUTHL Outputs 4 hex digits contained in HL to CRT In : Number to be printed in HL Out: ?? F030 HOUTA Outputs 2 hex digits contained in A to CRT In : Number to be printed in A Out: ?? F033 ?? ?? In : ?? Out: ?? F036 COUTA Outputs character in A to CRT In : Char to be printed in A Out: ?? F039 ?? Prints CRLF (does more, though) In : ?? Out: ?? F03C CONIN2 Gets char like CONIN, but also echoes it to screen In : ?? Out: Char in A (loops until char avail) F03F ?? ?? In : ?? Out: ?? F042 PRSTR Outputs string to CRT. String immediately follows call, terminated by 04. Returns to instruction following 04. In : ?? (uses return address for start of string) Out: ?? (The following are monitor high-level function calls) F7F0 DUMP Dump memory routine In : ?? Out: ?? F7F3 ?? ?? In : ?? Out: ?? F7F6 MEM Memory examine/change In : ?? Out: ?? F7F9 F7FC F7FF F802 ?? ?? In : ?? Out: ?? F805 TYPWR Typewriter In : ?? Out: ?? --- Overall there is a smell of fried onions. (fnord) :+: Pat Mancuso :+: Penn State University Usenet: :+: ...!psuvax!mancuso Bitnet: :+: mancuso@psuvax1