[sebhc] H17 ROM ?

Steven Parker sp11 at hotmail.com
Fri May 21 15:39:13 CDT 2004

Dave says:
>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 
last message.

>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 
own controller.

Ron said:
>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.


- Steven

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