20 Dec
2013
20 Dec
'13
4:12 p.m.
On Fri, 20 Dec 2013, B. Degnan wrote:
> I'm assuming that there's some
incompatibility between the ACB-4000 and
> the boot PROM. It would help to know what it's expecting to see. I've
> been digging through the boot ROM sources, but nothing jumps out so far.
Steve,
What OS are you using? I understand that the original
OS had an OS bug
related to direct hard drive booting. I can check around if you have not
yet resolved the problem
Hi, Bill.
I think you are close. Yesterday I discovered their 'boot.com' utility.
It is intended to cold-boot the machine from any arbitrary attached device
regardless of DIP switch setting. In looking at the source code, I
discovered that it can also read an arbitrary file from disk and use that
instead of the boot PROM on the system board. When I told it to use the
'maxrom13.com' image on the CP/M distribution diskette, lo and behold it
booted the hard drive!
I popped open the unit and sure enough the PROM was labeled "Lobo 1.2".
So it looks like the fix went in with version 1.3 and I'll need to blow a
new PROM.
Unfortunately, when reassembling the unit I managed to get the ribbon
cable between upper and lower PCBs off by one pin and smoked several chips
on the keyboard portion :-(. It took out the LS240 that reads the
keyboard matrix and both LS05s that provide the matrix scan from the
address bus. I'm about half way to having it up again. Good to keep
one's bench skills sharp...
In order to blow an LS472 PROM, I need to build the appropriate jumper
headers for my programmer - a job in itself. But I'm reasonably sure that
will get it starting from the hard drive.
FYI: The Adaptec ACB-5500 seems to be the most compatible SASI controller.
Steve
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