A Compukit UK101

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Doubletop
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Joined: Sun Jan 05, 2020 6:19 am
Location: Wellington NZ

A Compukit UK101

Post by Doubletop »

I was in the loft getting down the Christmas decorations. I also bought down two computers I built some years ago. This first one was built from a kit in 1979 and bits got hacked and added on over time.

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It’s a Compukit UK101 a Brit knock off of the Ohio Scientific Superboard. It came with 4Kb of RAM and the upgrade to 8Kb cost me £50, equivalent to £285 today. That would buy you a top end Intel I7 processor.

It got heavily modified over time, ending up with 64Kb RAM And floppy disk drives for 8” disks that held 128Kb of data! It became the development platform for #2 but more of that later.

Internals

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Main Board

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PSU 5V 10 Amps - no switch mode here.

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Home made expansion card AtoD DtoA and other things I can't remember

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Underneath the main board is a genuine OSI 64k expansio card and disk controller. I did have 8"drives and OS65d, but the disks and drives are long gone.

Then came the full homebrew. It started life as an add on to the UK101 with a circuit board connected to the original 6502 microprocessor socket and provision for 6502, Z80 and 6809 microprocessors plus a floppy disk interface. See the three original circuit diagrams that I found in a box of papers.

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It never saw a 6809 and more and more was added to it that eventually the two computers were separated and all the new boards put in an old rack chassis.

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Z80 Based it runs CP/M 2.2. It grew, at first with 8” floppy disks , then 5.25” disks and then a hard drive. Getting that going is the current task so I can save everything on the hard drive before it gives up. Then I'll tackle the UK101 and now I've found the resources here there's hope for it yet. Dave tells me that the Gotek USB drive I already have on order can emulate 8" disks.

Pete
"To achieve anything in this game, you must be prepared to dabble on the boundary of disaster" - Sterling Moss
dave
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Re: A Compukit UK101

Post by dave »

Welcome, Pete! Both of the systems look really cool. It will be great to see it up and running!

Dave
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Doubletop
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Joined: Sun Jan 05, 2020 6:19 am
Location: Wellington NZ

Re: A Compukit UK101

Post by Doubletop »

Dave

The UK101 is on hold at the moment. I was working on the CP/M system but now I've got the Gotek USB disk unit on order I'm going to park working on anything it until it arrives. To get the CP/M system to run I have to fire up the 10Mb hard disk and it makes some strange noises at times. Once I have the Gotek up and running I can copy everything off the HD and then any tinkering shouldn't result in a disaster. I had trouble getting it to start yesterday and once it did it locked up and threw some text on the screen that is in the BDOS. That caused a moment of panic. Two hours of timkering got it runing again without knowing what I'd done. No doubt dodgy IC pin connections.

Pete
"To achieve anything in this game, you must be prepared to dabble on the boundary of disaster" - Sterling Moss
nama
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Joined: Wed Mar 30, 2011 9:44 am
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Re: A Compukit UK101

Post by nama »

For the Gotek to emulate 8" floppies you may consider getting one of these:

https://gitlab.com/NF6X_Retrocomputing/fd50to34

2P (1mhz 32k) - 502 + 8k + CEGMON + garbage collector fix BASIC, D&N MEM-CM9 + 24k, 540 (mono) [SOLD]
4PMF (2mhz 24k) - 505, 540, 527, D13 + 5.25" + Gotek
Superboard RevD - CEGMON + 610 board 24k + D13
Spares - 3 x 527, 1 x 505, Backplane
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