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Commodore PC10 III BIOS

A

archeocomp

Experienced Member
Joined
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416
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Hello. I have bought two PC/XTs off eBay Germany. One is PC 10 III with MFM card and HDD, the other one is PC 20 III with RLL HDD. I do not have any TTL monitor. Week ago as I only had the first one, I did power it up, just to let it heat up. Before everything went fine, I could hear the computer beep after RAM test, though I did not see anything. But this time after a while I heard an explosion and the power supply fan did exhaust a lot of smoke. So I switched it off and disassembled. A capacitor at the input in power supply exploded. I replaced it. Power supply seemed to work, I measured all the voltages and it seemed OK. So I started the PC agan. And it did not start. The LED in the front just blinks. So it seems, the motherboard is damaged. I removed the BIOS chip and wanted to read it contents. Sticker says it is BIOS4.36. All FF. I tried to program one byte. No succes. So the EPROM is dead. But I tested the MFM card in yet another PC/XT. It works !! So not everything has been burned. Today I received the other PC 20 III I mentioned in the beginning.
http://www.ebay.de/itm/110936163204?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
I cleaned it, it was very badly dusted, rosty. I wanted to read the BIOS chip. Sticker says it is BIOS 4.41. And it seems almost cleared. Here are the first lines:
:2000000055FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFAA
:20002000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0
:2000400064FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5B
:20006000FFFFFFFFFFFFFFFFF7FFFFFFFFFFFFFFFF07FFFFFFFFFFFFC7FFFFFFFFFFFFFFD8
I think the EPROM may not be dead, it only lost its contents. Now my question.
1. Could somebody please upload some BIOS for these PCs ?
2. I know nothing about different PC/XT BIOSes, are they interchangable ?
3. I see there is another CHAR ROM on the motherboard. Can someone upload it contents as well.

In a week or so I should receive this TRIDENT 9000 card, I want to test the PC with LCD VGA then. It hopefully is an 8 bit friendly card.
http://pocitace.aukro.cz/vga-karta-trident-i2551448516.html

Any thoughts, comments, help are welcome.
Regards,
Roman
 
archeocomp said:
1. Could somebody please upload some BIOS for these PCs ?
Click to expand...
If someone does, then I can host it at http://www.minuszerodegrees.net/rom/rom.htm

archeocomp said:
2. I know nothing about different PC/XT BIOSes, are they interchangable ?
Click to expand...
I am unfamiliar with the Commodore PC10-III, but I can see lots of information about it on the Internet.
The PC10-III motherboard differs greatly from that of the IBM PC, IBM XT and close clones of those two.
Therefore, I do not think that ROM images that you find for those computers will be suitable for the PC10-III.
 
I am unfamiliar with the Commodore PC10-III, but I can see lots of information about it on the Internet.
The PC10-III motherboard differs greatly from that of the IBM PC, IBM XT and close clones of those two.
Therefore, I do not think that ROM images that you find for those computers will be suitable for the PC10-III.
Click to expand...

I owned a PC20-III - indeed it was still a commodore machine that had gotten some attention, not a mindless clone.
CGA/HGC switchable, 8bit IDE harddisk, etc.
Maybe it was lucky enough already that it was compatible at all
icon_smile.gif


But hey, forum member Tezza has a PC10-III?
http://www.classic-computers.org.nz/blog/2010-11-18-exploring-a-commodore-pc-10-III.htm
 
Many Moons ago i scrapped a PC10 lll but kept the Mobo, I dug it out and dumped the Bios chip, The lable on the chip reads: 318085-02 PC 3 BIOS 4.36 The machine was probably in very poor condition and incomplete hence why it got binned, Bios dump attached though no guarantees.

Malc
 

Attachments

  • PC10_lll.zip
    18.3 KB · Views: 4
Malc said:
Bios dump attached though no guarantees.
Click to expand...
Thanks for that. The 8-bit checksum of the image is 2A. Had it been 00, then I would have confident about the image's integrity, however maybe Commodore doesn’t use 00 like most others.

Of course, if archeocomp uses the image and it works, then that would suggest that the 2A is normal for this version of the ROM. If it doesn't work for archeocomp, then he won't know if the cause is a corrupt image or something else that's wrong with his motherboard.

If someone else posts a ROM image, we'll have a better indication.
 
Thank you. I can confirm that this image is 100% OK. It is binary identical to the one found here:
http://mhv.bplaced.net/cbmroms/cbmroms.php
This page's author has collected a huge amount of Commodore ROM's.
When I receive my VGA card and a new EPROM programmer (cause my chinese has stopped working yeasterday) I wil try the image. That will not be sooner as in two weeks. I also have probably the latest version for PC10-III, the 318085-08, that is Version 4.41. It is dated on 30.nov.1990. I can post it now or later when I have tested it.
 
tezza said:
Yes, I did. Unfortunately no more though ):
Click to expand...

Don't even think about coming up with any excuse, there isn't one! :p
(yes I read the last line on your blog after I posted here)

This PC20-III I bought was my first pc. I sold my C64 to be able to buy it, which I regretted a long time, but there was no other way.
 
As an aside, if I remember correctly, these machines have composite out.
There are switches on the back to configure the video port, if it's set to CGA (Colour) then I'd expect the composite port to throw out a signal your TV can display with a simple RCA lead.

The onboard graphics were quite cool in that they could drive MDA or CGA/EGA displays.

Although this is from my memory, and it's been a long time.

Might help until you get a TTL display.
 
I have tested my PC10-III boards in the last two days. The one with revision 5.9 seems to work, the other one with revision 6.2B does not work. I have tested BIOSes form both on the working one. The board rev 5.9 originally contained BIOS 4.36. This has been already uploaded. The rev 5.9 board works also with BIOS 4.41 from the non working board revision 6.2B. Here I am uploading it for everyone.View attachment PC10-III.4.41.BIOS.zip
Computer works, boots into DOS and 360kB floppy lights up. It is too late to test the floppy. Tomorrow I will test it further with different floppy drives. Rumours say this BIOS revision could even support HD floppies.
 
So I tested the newer BIOS more thoroughly. I ran CheckIt main system test and it passed. I also succeeded attaching original 360k drive as A: But I did not succeed in attaching any other drive to it. I tried attaching another 360k but both where acting at the same time. The LED came on both all the time. The cable has no twist though. When I attached 1.2M drive BIOS wrote at start time A: drive BAD.

I do not really understand this. Do the drives have to be jumpered to A: and B: respectively ? The FDD chip
FDC9268 on the mainboard is capable of supporting HD drives. But how to make BIOS recognize them ? Even yet another 360k drive was not recognized, but this one is maybe faulty.
 
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archeocomp said:
I also succeeded attaching original 360k drive as A: But I did not succeed in attaching any other drive to it. I tried attaching another 360k but both where acting at the same time. The LED came on both all the time. The cable has no twist though.
Click to expand...
In the IBM PC, the specially twisted cable is mandatory.
Both floppy drives are set to DS1 (the second Drive Select option).

A diagram is shown at http://www.minuszerodegrees.net/images3/floppy_crossover_cable_wiring.jpg
Photo of twisted cable at http://www.minuszerodegrees.net/misc/floppy_vs_hard.jpg
 
modem7 said:
In the IBM PC, the specially twisted cable is mandatory.
Both floppy drives are set to DS1 (the second Drive Select option).
Click to expand...
Yes and not. The cable without twist was originaly in the one of the PC10-III. And this one had combination of a 5.25 362k A: drive and 3.5 720k B: drive. The B: drive is TEAC FD-235F 100-U. It has UNJUMPERED MS header. This problably makes it to act like B: drive. I actuallly happen to have one more of these drives. The other one has been salvaged from Bondwell B200, there it had MS pins jumpered. And I tested (with unjumpered MS) both now, so I can sort out hw problem. I behaves like this. ON start up drive A: ligths up, after that the light on B: drive comes up. The PC boots without complaining about drives A: or B: and Norton Commander sees drives A:, B: and C:. So the B: is definitile recognized. When I try dir b: or format b: though, the B: drives lights up but after long time I get mesage "not ready". But again, the B: drive is difinitley accessed and try to do something. This setup was found orginally in the one of these Comoder PC10-III. Why the B: drive does not work now ?
 
I succeded in attaching 720kB 3.5" as B: drive. I did not success trying 1.44MB drive. I used a non twisted cable. The A: 360kB 5.25: drive is jumpered as DS0. That makes it behave as it would be after the twist. The B: is TEAC FD-235F and must have Motor Select MS pins jumpered. It seems that the controller does not provide Motor On signal. The drive motor is turned on by the Drive Select. Last step was an entry in config.sys.
DEVICE=C:\DOS\DRIVER.SYS /d:01
This creates a logical drive that has factor 2 -> 720K (3.5-inch disk). This is default factor so it could be left out from the parameters. I tried an 1.44 drive too, but there seem to be two problems:
1. the motor does not spin
2. the dos still thinks it is an 720kB drive

And I bought a beautiful PHILIPS green 12" monitor and an 8087 coprocessor as well. And the HDD seemed dead at first. It's heads were probably stuck. It could not boot, BIOS could not detect it, it only made a lot of noice. Next time it got detected, but booting failed on read errror. With each power on I could get further, when on approx. 5th time it booted succesfully. The HDD has no bad blocks once it got operational again!! Now this little nice PC10-III lives again ;)
27092012013.jpg27092012014.jpg
 
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I need a new BIOS for my Commodore PC 20-III. I accidently damaged the rom so now it's toast.
Do any of you who read this have the possibility to make me a new one and send it to me in Sweden?

Of course i'd preferably take the 4.41 version as it seems to be the newest one but any from 4.36 and up would work for me if you have one you don't need.

Please help me!
 
Looking for the latest BIOS ROM for the Commodore PC10-III. Anyone have it? I tried the site above but it asks for a username and password.

EDIT, I see post #13 has an attachment, I will try it!
 
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