[sebhc] H17 ROM ?
sp11 at hotmail.com
Fri May 21 15:39:13 CDT 2004
>I've been disassembling the H17 ROM (found it in the archive),
>As far as I can tell, it has very little to do with the disk
>hardware - it appears to be chock full of various utility
>subroutines (like divides etc.) but almost no disk functions.
>Just a little boot stub at the end.
Are you looking at your disassembly, or just that partial listing in the
archives? (That listing only shows the very beginning of the ROM).
Disk-related entry points in the H17 ROM include:
R.SYDD EQU 033316A ROM device driver
R.MOUNT EQU 033345A Mount new device
R.ABORT EQU 033366A Abort any active I/O
R.XOK EQU 033374A Exit with OK status
R.XIT EQU 033375A Exit
R.READ EQU 034077A Read from disk
R.READR EQU 034321A Read regardless of protection
R.WRITE EQU 034336A Process disk write
R.CDE EQU 035136A Count disk errors
R.DTS EQU 035172A Decode track and sector
R.SDT EQU 035225A Seek desired track
R.MAI EQU 035251A Move arm in
R.MAO EQU 035254A Move arm out
R.DLY EQU 035303A Delay by clock
R.LPS EQU 035321A Locate proper sector
R.RDB EQU 036044A Read disk byte
R.SDP EQU 036062A Set device parameters
R.STS EQU 036165A Skip this sector
R.WHD EQU 036235A Wait for hole detect
R.STZ EQU 036254A Seek track zero
R.WNH EQU 036271A Wait for no hole
R.UDLY EQU 036302A Microsecond delay loop
R.WSC EQU 036307A Wait for sync character
R.WSP EQU 036343A Write sync pattern
R.WNB EQU 036373A Write next byte
BOOT EQU 037014A Boot disk system
DDIAG EQU 037262A Disk diagnostic
As you see, the ROM has an entire device driver - but it may be easier to
look over the source for the HDOS driver (sydvd.asm) that I mentioned in my
>I had been assuming that the ROM would contain all the disk
>functions, so that the operating system could access the disk
>no matter which controller/drive you had installed
Different controllers had different ROMs. The H17 ROM only addresses its
>Look in the PAM-37 Panel Monitor Operation/service Manual. That book
>contains a listing with routines for and references to all the disk types.
I don't think the PAM-37 listing has made it into the archives - I've been
looking for it myself. Ironically, even though I am the author of PAM-37, I
don't have a copy of the listing!
But yes, PAM-37 was the only monitor ROM able to boot from all the disk
flavors, and that was a major objective of the development project.
However, as I recall, it still relied on the code in the controller ROMs.
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