Science Of Cambridge MK14 Replica build

[rubber_jonnie]

More parts arrived today, and I am getting closer to having all the parts I need.

I joined this forum: Vintage-Radio.net

And they have been super helpful.

I was missing the following:

1. DM80L95 Hex buffer
2. MM2111 RAM
3. NSA1198/88 LED display

And with their help I now know the 80L95 can be replaced by a 74LS365, so I have some coming, plus I have an adapter board on the way to replace the original LED that was the same as those used in a Texet 880 calculator.

I didn't want to destroy a retro calculator, so that made sense.

So, just RAM to source now, hopefully I can find some at less than £14 an IC!!!

[rubber_jonnie]

Woo hoo, more parts for the MK 14 😁

IMG20240717190606.jpg

[rubber_jonnie]

Good progress tonight:

IMG20240717221900.jpg

That's all the sockets installed and all the caps, resistors and other items. The crystal, display and other missing parts (Bar RAM, I'm working on that) are on the way.

Given the cost of the CPU and I/O IC I will power the board on without any IC's installed and make sure the correct power is in the correct places before I plug anything in. I really don't want to see magic smoke...

Should be there reasonably soon :)

[stephen_usher]

:dualthumbup:

[PhilC]

That was quick. Time for a C128 board next perhaps? :lol:

[rubber_jonnie]

That was quick. Time for a C128 board next perhaps? :lol:

Well, it's a very small project 😁

The C128 is still in my sights but I also have an H4 and H5 to do too, so I have plenty of content.

:dizzy:

[rubber_jonnie]

OK, chips out smoke test has passed (No smoke) and voltages go where they should in the IC sockets :)

Also no shorts, though this is a lot easier than the OSI 600D as it actually has got solder mask, so less chance of solder bridging traces.

Whilst I'm waiting for more parts to arrive I'll probably start populating the LS ICs and see how a power on test goes with those.

The display should arrive tomorrow too, and I'm hoping the remaining parts, bar the RAM (I have RAM on order, it may take a while to arrive...) will be here in time for the weekend.

[rubber_jonnie]

Getting close now:

IMG20240718112720.jpg

The RAM is unfortunately coming from France, so that'll be the hold up, but I should have everything else by the weekend I hope.

[rubber_jonnie]

Well, the crystal arrived along with the 74LS365, so I did a little testing.

There is a correct clock at the CPU, so things are looking positive, display will arrive tomorrow by the looks of things, so then it's the wait for the RAM.

Getting a lot of good vibes from it :)

[HigashiJun]

Looks really good !

Well done.