Electronic Circuits and Projects Forum

Originally Posted by ericgibbs

Hi Mike,
I have used the 8255 as an expander in the past with good results.

But the 8255 is a really limited 'horrible' device, there are MUCH better PIO chips available (like the 6522 for a start).

But considering this is supposed to be for a 'relay computer', isn't the memory supposed to made of relays? - isn't that the point?.

Originally Posted by Pommie

That should indeed be the point. However, if you look at the link I posted on the other relay computer thread then the relay computer is the ALU and associated address/data busses. The actual memory used was silicon. Even with silicon memory the thing was still huge and not something I would like to attempt building. If you did do relay memory then you are going to be pushing the envelope at 256 bytes.

Well based on past experience, I don't think there's a chance he's going to build it anyway!

Originally Posted by Pommie

We were all that enthusiastic once and shouldn't knock it. However, your probably right.

Considering this
http://www.electro-tech-online.com/r...ht-seeker.html
is about as far as he goes, I can't see him building anything like a relay based computer

And to be honest, it's seriously a complete waste of time and money anyway, if (for historical reasons) you wanted to see what one was like, it would be fairly easy to write a simulator on a PC.

Originally Posted by Nigel Goodwin

But the 8255 is a really limited 'horrible' device, there are MUCH better PIO chips available (like the 6522 for a start).

But considering this is supposed to be for a 'relay computer', isn't the memory supposed to made of relays? - isn't that the point?.

hi Nigel,
I did say in the 'past', I suppose I should I should have said, 'in the distant past'.
Remember at one time time, it was cutting edge!.

Originally Posted by Pommie

Nigel,

The youth of today should be encouraged at every step. Krumlink appears to have a lot of enthusiasm and gets on and does things. Let's encourage him and others to have a go.

Mike.

Mike,

For whats its worth, I agree 100%

I achieved most of my goals and I try to help others to do the same...

3V0 managed to focus Krumlink for a short while, and Krumlinks school robot (with the globe) looked great (was it a VEX?).
Krumlink appears to be driven by visual / physical projects. A microcontroller IC looks pretty meek and may appear uninteresting compared to something mechanical.

Differential engine (an early mechanical computer) the meccano version is a monster.

This wee 12F509 device is a very power micro computer