[Coco] A hint for NitrOS-9, MPI, and "hard drive" PAK

[Gene Heskett]

On Thursday 19 December 2013 11:30:18 Luis Antoniosi (CoCoDemus) did opine:

> SALT chip ?
> 
> There is one online copy:
> 
> https://archive.org/details/TandyServiceManualColorComputer3
> 
> hard to see the schematics though

They will enlarge, and the detail is good, nice scan. An SC77527 failure is 
entirely possible.  I wonder if the shack (or Mark) has any spares? I'd 
imagine I'd better put a heat sink on the replacement, and in a socket too.  
I am only seeing 5 volts or nearly ground at the 4 pin din, which I think 
confirms the diagnosis.

My 2 meg memory kit covers that whole area, so that will need to go in 
order to make other measurements. Like verifying that the +-12 is actually 
getting to the salt chip.  Should be an interesting replacement. Not.

Thanks Luis.
> 
> On Thu, Dec 19, 2013 at 10:54 AM, Gene Heskett <gheskett at wdtv.com> wrote:
> > On Thursday 19 December 2013 10:43:40 Robert Gault did opine:
> >> Many years ago I wrote a Basic09 utility to graphically display a
> >> floppy drive's RPM. Just recently I was booting NitrOS-9 using Roger
> >> Taylor's Drive Pak and my rpm program crashed NitrOS-9. This is the
> >> same code that works when booting NitrOS-9 from my scsi hard drive.
> >> Let's make it very clear that the problem was NOT Roger's Drive PAK.
> >> Well this bug drove me crazy for about a week. Finally I found out
> >> what was wrong and I expect that any user of a "drive" PAK
> >> regardless of make is likely to run into the same bug.
> >> 
> >> My Coco system is a Coco3, MPI, two scsi Hard drives, DistoSCII in
> >> slot4, hard drive interface in slot3, RS-232 PAK in slot2, and a
> >> Drive Pak in slot1. Recently I've had the slot selector set to #1
> >> and have been booting NitrOS-9 from the Drive PAK.
> >> Well when I booted from the hard drive, the MPI selector was set to
> >> slot4 which made the floppy controller active. When booting from the
> >> Drive PAK with the selector in slot1, the floppies had not yet been
> >> used.
> >> Hmmm, my program POKEs the floppy controller but if that has not been
> >> initialized either by hardware or software ....
> >> 
> >> Well adding a single line to the Basic09 program let the program work
> >> correctly regardless of where the MPI selector was set during the
> >> boot process: SHELL "iniz /d0"
> >> 
> >> This is not something you would expect to be required, and I never
> >> needed it when booting from the scsi hard drives even though both
> >> kernel and OS9Boot were on the hard drive and not a floppy. I still
> >> don't understand why the above line is needed as OS-9 does not mess
> >> with the MPI unless a driver requires it. Still with the recent
> >> interest in ROM and Drive PAKs, if you have unexpected crashes with
> >> previously working programs, keep the above in mind.
> >> 
> >> Robert
> > 
> > Thanks for the heads up. And I am out of the drivewire business until
> > I can get my coco3 fixed, I've apparently blown something in the
> > bitbanger circuitry while trying to make inetd actually work.
> > 
> > Most will recall that I've long ago converted my system to run on an
> > old AT power supply, which puts a true + and - 12 volts into the com
> > circuitry in the coco which usually limps along on +-8 volts or so. 
> > The extra voltage seems to have overheated and destroyed something in
> > the bitbanger when it was being asked to handle, non-stop because of
> > some sort of an error loop, something over 1000 packets a second
> > according to the server, which was echoing 10: Unk API back at the
> > coco just as fast, and taking from 10 to 97% of one core of a phenom
> > 4 core cpu to do it here on this machine.  I let it run that way for
> > a couple days, so an overheating related failure is quite possible.
> > 
> > And somehow, despite owning 2 copies of the coco3 service manual, I
> > can't find either in my "midden heaps" here or in the basement. 
> > They'll turn up eventually, but...  I am out of business in the
> > meantime.
> > 
> >> --
> >> Coco mailing list
> >> Coco at maltedmedia.com
> >> http://five.pairlist.net/mailman/listinfo/coco
> > 
> > Cheers, Gene
> > --
> > 
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > 
> > -Ed Howdershelt (Author)
> > Genes Web page <http://geneslinuxbox.net:6309/gene>
> > 
> > Win98 error 003: Illegal ASM instruction. If your modem worked
> > properly, the
> > FBI would have been called.
> > A pen in the hand of this president is far more
> > dangerous than 200 million guns in the hands of
> > 
> >          law-abiding citizens.
> > 
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > http://five.pairlist.net/mailman/listinfo/coco


Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

There are times when truth is stranger than fiction and lunch time is one
of them.
A pen in the hand of this president is far more
dangerous than 200 million guns in the hands of
         law-abiding citizens.