Commodore PC10

After Tramiel left Commodore in 1984, the company started to look for other fields to explore. In mid-1980s PCs gained much popularity and Commodore started a large family of IBM PC clones. Probably the first one, PC5 released ca. 1984, had single floppy disk drive and 512kB of RAM. Next models, PC10 and 20 (1985), used the same casing left from Commodore's graphics workstation (so in early PC10 and some PC20-II mainboard had to be split to two boards connected by goldpin interconnect), and PC20 was a cost-reduced version of PC10 with single floppy drive. In 1986, PC-20 got a 20MB hard drive and was sold as PC20-II. All of them used different ATI graphics adapters compatible with MDA, CGA or Hercules, sometimes in one board.
The problem was that PCs manufactured by Commodore (mostly in Germany) were not much different than much cheaper Chinese and Taiwanese clones. So after releasing next versions, previous were made even more "cost-reduced" giving a mess of revisions, versions and editions. PC10 without hard disk was manufactured until 1987 when mainboard was re-designed and... sold as PC10-1 (one FDD, 512kB) and PC10-2 (2 FDDs, 640kB) leaving HDD branch to PC20-II and later types. The goal of these maneuvers was to make older PCs cheaper and, in perspective, more affordable than Asian clones. But even introducing a home-oriented small PC-1 in 1987 did not saved Comomdore's situation with PC clones.
In Europe, Commodore PCs got some small popularity in Germany where they were manufactured, but in other countries they were much more expensive than Taiwanese PC clones. Because PC was, in user's perspective, just a PC with all PC software, most customers bought cheaper Asisn PCs with the same specifications.

Manufacturer Commodore

Origin USA / Germany
Year of unit 1986?
Year of introduction 1985
Class XT
CPU Intel 8088
Speed 4.77MHz
RAM 640kB
ROM Commodore PC BIOS
Graphics CGA/Monochrome (ATI Graphics Solution rev. 3)
Sound PC Speaker
System expansion bus 8-bit ISA
Floppy/removable media drives 2x 360kB 5.25" floppy drives
 
 

Hard disk: 20MB Kalok KL-320 (non-original)

Peripherals in collection:
 - Commodore 1402 monitor (monochrome, white, manufactured by Hyundai)
Other boards:

 

 Controller for hard disk
Non-standard expansions:  
Operating system(s): MS-DOS

My unit has been built for German market, but it was probably bought by Polish customer. The monitor (Commodore 1402) is later, and CPU probably had some other one. In 1990 hard disk upgrade was installed.
As I got it, hard disk was not working After making ribbon cable more stiff it was possible to make it running with relatively small amount of bad sectors. I've added 256kB to sockets in mainboard to have 640kB of memory.

The mainboard's ISA slots part has holes drilled in tracks, these drills were made in factory.

To quickly distinguish between German and American Commodore PCs, look at floppy disk drives - in my German unit they are operated by pushbutton, not turning lever. German PCs had BASF drives with button mechanism, while USA PCs  had Alps with lever.

Contents: Starting, usage Jumper settings Links

Starting

By hardware it is a bit different than IBM's PC, as it has PLAs and GALs, as well as RS232 and Centronics onboard, but for software it is compatible with IBM PC. It just boots DOS from floppy you give it.

After power on, BIOS starts displaying frame with information and counting memory as part of POST. Then it emits series of high-pitched sounds and tries to boot from floppy.

 

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Jumper settings

As of today (2016) it is a bit hard to get jumper and DIP switch settings. These settings have been compiled from similar Commodore computers documentation and tested in my unit.

In the mainboard, there is a DIP stiwch bank near interconnection of two boards (1 - ON, 0 - OFF):
1 - Deafult OFF - ON reboots after memory test. For factory burn-in testing
2 - Default ON - OFF if 8087 is installed
3,4 - 00 - 640kB of RAM installed, 10 - 512kB of RAM installed, 01 - 256kB of RAM installed, 11 - 128kB of RAM installed
5,6 - Factory set to 0,0
7 - Default OFF - On deactivates floppy disk drives
8 - Default ON - ?

ATI Graphics solution Rev. 3 has a DIP switch bank on its edge. Near DIP switch bank there are 3 connectors. The two-pin one is in most ATI cards a composite video output (it should be checked before using), while longer one is for light pen. I don't know what is the third one for. Switch 1 is closer to the bracket. I am not certain of these settings (deduced from SE and Rev. 2 versions), you have been warned. The possible DIP switch meanings are:
1,2 - 10 - monochrome adapter, 01 - CGA, 00 - CGA emulation
3,4,5 - 100 - TTL RGB/monochrome monitor, 011 - Analog monochrome or composite monitor, 000 - EGA monitor
6,7,8 - Factory set to 100.
JP1 is factory set to 2-3.

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Links:

http://www.zimmers.net/anonftp/pub/cbm-pc/ALLFILES.html - Interestong files in Bo Zimmerman's site. Service manuals, diagnostic manuals, disk images, ROM dumps...
http://dostalgie.de/downloads/pc10-20-10II-20II/PC10_II_SM_COMMODORE_EN_DE.pdf - Mainboard is the closest to this design.
http://www.europeana.eu/portal/pl/record/91658/MM_objekt_1089824.html - described as PC 10
http://gona.mactar.hu/Commodore/monitor/schematics/1402_Monitor_Service_Manual.pdf - Commodore 1402 service manual



 

 

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