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Showing posts from August, 2017

The problem with memory

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It's time, at last, to start looking at the design for the computer's memory and this is a bit of a game changer as it's the final part of the jigsaw that lets the computer run a program. However, it's also the part of the computer that leaves me in a bit of a quandary.

The problem with memory is that typically you need quite a lot of it and that's something that doesn't come easy with relays. In a way the registers already present in the computer are a kind of memory ... they store a single byte of data. So, effectively you can get two bytes worth of storage on one of the usual computer cards. You can maybe see where this is going.

Each instruction in a program takes a byte of memory therefore a 10 line program needs 10 bytes of memory. How long does a program need to be? Well is depends but for this kind of computer 20 to 30 wouldn't be unreasonable it you're going to do something 'interesting'. It's not just the instructions that need sto…

More Laser Cut Parts

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I've nearly got the design for the memory cards done and ready to share but once that's out the way it'll be time to get on with some construction again. With that in mind I cracked out the credit cards and got buying more relays plus some other bits and bobs and whilst I was in a spending mood I decided it was high time to treat the computer to some more laser cut parts.

The two displays (A and B) in the upper enclosure have been looking a bit 'unfinished' and it was always my intention to get some laser cut panels made up eventually which would surround the switches and LEDs and give it a more 'polished' look. Additionally the panels would also carry an engraved legend to explain what each group of switches/LEDs represents in the displays. The process for making these is just the same as before when I got the laser cut panel for the primary switches.

As before I've chosen to get my laser cutting done through RazorLab who provide starter templates for …