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
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