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A project log for GTXL Gigatron clone computer with keyboard

Microcomputer that runs without a CPU

justin-davisJustin Davis 11/14/2018 at 13:014 Comments

Still building - not quite to blinking lights yet.  Lots of soldering.  I ran out of 20-pin sockets, so I had to put some on order.  I also didn't realize I had no 750 Ohm resistors.  I've also been seeing if there's a drop-in ZIF socket for the ROM, but I haven't found one yet.  I probably should have thought of that during layout.  It may help if I do lots of ROM updates.  More likely I will just build the cartridge with reprogrammable memory.  

While I'm waiting I can start loading chips and testing starting with the ALU and then the X/Y registers.  I'll wait for the Cherry MX keys until I have everything else checked out since they are fairly expensive (at 63 of them are).


Discussions

Dr. Cockroach wrote 11/14/2018 at 20:24 point

I have a lot of 750 ohm resistors if you want me to send some. Just message me your address and they will be on their way :-)

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Justin Davis wrote 11/16/2018 at 17:22 point

I already have some on the way, but thanks for the offer!

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Marcel van Kervinck wrote 11/16/2018 at 23:58 point

Or just use 680 ohm. Its all analog in that area, your eyes aren't going to spot the difference.

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Dave's Dev Lab wrote 11/14/2018 at 18:35 point

try looking for some Low Insertion Force(LIF) sockets instead of Zero Insertion Force(ZIF). i've used them on a number of projects recently and they are much more cost effective that ZIF. https://hackaday.io/project/158510/logs?sort=newest&page=3

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