Posts

Showing posts from February, 2014

ALU Construction: Completed Arithmetic Card Full Test

Image
The ALU arithmetic card is now complete! The final card looks like this:
As I did for the ALU logic card before I've put the following YouTube video together which gives a walkthrough of the arithmetic card in operation ... and as before this one also has a narrative track delivered by my own fair gob.


So, that's two out of the three ALU cards done with just the control card left to do. Well, I say that ... after the ALU is completed there's all those registers let alone all the control and timing circuitry coming up ... I'll try not to think too much about the impending work for now.

The control card should prove a bit quicker to put together as there's less relays, wiring and soldering to contend with. Oo - and for my next post I'll share what I've been up to in SketchUp for the enclosure design.

ALU Construction: Arithmetic Card Wire Wrap 2

Image
I've managed to squeeze in a couple more wire wrapping sessions this week so in this post there's a few photos of progress so far.

Inputs B and C are fully wired in now as is the data bus output. As all the wiring is now complete on the arithmetic 1-bit units I've popped the relays in.


The next wire links to add are the control lines which select either the Add or Increment operation and then once that's done the card should be ready for powering up and testing/debugging.

ALU Construction: Arithmetic Card Wire Wrap 1

Image
Fear not (just in case you were for some reason) all this talk of Sketchup and enclosures and so on hasn't totally diverted me from the main task of constructing the ALU. The wire wrap is coming along nicely on the arithmetic card although it has taken slightly more concentration than before to get all the wraps in the right places.

Here's a couple of pictures showing the card in its current state of progress:
All the 'internal' links (black wires) in each 1-bit arithmetic unit are complete along with the display links (also black wires) that run from each unit to the LEDs on the front. All the green wiring is also complete which runs the internal results between each 1-bit arithmetic unit and on to the gating relays at the top right of the board.

The next links to be wired in will be:

Red power lines supplying each 1-bit unitBlue input B and C lines (with input B permanently connected but input C routed through gating relays at the top left of the board)Blue result lin…

Sketchy Diversion

Image
I'm taking a break ... just a short one.

In between all the bouts of wire wrapping for the ALU arithmetic card I'm starting to think about enclosure options for the computer when it's finally (finally!) finished. I've been trawling the internet for inspiration and I'm starting to get a feel for the sort of materials and finish I want and I've even been getting some prototype laser etching done (more on this in a later post). One thing I'm finding as I'm going along though is that I'm trying to picture things in my head and there's a lot of guesswork going on. What I need is to employ some CAD so I can make sure things fit together before really fitting them together.

So, cutting to the chase, after a couple of hours getting up to speed with the very usable SketchUp I've created 3D models of all the cards I've constructed so far and it looks like this:
... and with all the boards (virtually) plugged together it looks like this ...
This pr…