19 Aug 2014 - 2 min read
ALU & Registers A-D Test with new Display Cards
Now that the two display cards are complete enough to display and control the status of the ALU and four registers (A-D) it’s time to fit them to the upper enclosure. …
30 Mar 2014 - 3 min read
Following my last post on the completed backplane I’m now in a position to connect all the other completed cards together to test the full ALU. The ALU is made up of the …
26 Mar 2014 - 3 min read
ALU Construction: Completed Backplane
In my last post I mentioned I’d suffered a bit of a set back with the construction of the ALU backplane. Well, the short version of things is that I’ve admitted …
16 Mar 2014 - 2 min read
ALU Construction: Completed Control Card Full Test
The ALU Control Card is now complete and looks like this: This card was, on the whole, much simpler and quicker to put together than previous cards (despite me initially …
14 Mar 2014 - 1 min read
ALU Construction: Control Card Power Rails & Wire Wrap
I’ve been a bit short of time lately so I’ve been working on the ALU Control Card in little bursts … but after lots of these little bursts I’ve now …
04 Mar 2014 - 2 min read
ALU Construction: Control Card Header Pins & Relay Sockets
Following on from the first two successfully completed ALU cards, for logic and arithmetic, it’s time to make a start on the control card (well, actually, the LEDs and …
23 Feb 2014 - 1 min read
ALU Construction: Completed Arithmetic Card Full Test
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 …
19 Feb 2014 - 1 min read
ALU Construction: Arithmetic Card Wire Wrap 2
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 …
16 Feb 2014 - 2 min read
ALU Construction: Arithmetic Card Wire Wrap 1
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 …
26 Jan 2014 - 2 min read
ALU Construction: Arithmetic Card Power Rails
Another round of soldering done … this time putting down the power rails on the arithmetic card along with some soldered wire links. This is the last of the soldering …
21 Jan 2014 - 2 min read
ALU Construction: 1-bit Arithmetic Full Construction
So, as mentioned in my last post this time I’ve put in the wire links and wraps needed to test the first bit of the arithmetic card. With these in place I can make sure …
17 Jan 2014 - 2 min read
ALU Construction: Arithmetic Card Relay Sockets
It’s always a fiddly job getting the relay sockets soldered in and the ALU arithmetic card proved no exception. With this in mind I’ve been spreading the work out …
06 Jan 2014 - 2 min read
ALU Construction: Arithmetic Card Header Pins
Following on from the successful construction of the ALU logic card in my last post it’s time to start off the new year with the next ALU card (number 2 of 3 ALU cards …
18 Dec 2013 - 2 min read
ALU Construction: Completed Logic Card Full Test
The ALU logic card is now finally complete! … well, it is now I’ve popped the last few relays into their sockets. The final card looks like this: As the old …
18 Dec 2013 - 1 min read
ALU Construction: Logic Card Wire Wrap 3
I’m now just one session of wire wrapping away from a completed ALU logic card. The final job is to wire up the gating relays that select one of the five logic results …
12 Dec 2013 - 2 min read
ALU Construction: 8-bit Logic Unit Tests
There’s now enough sockets, solder and wires to test all eight bits of the ALU logic card. This isn’t quite a full test as the gating relays that apply one of the …
12 Dec 2013 - 1 min read
ALU Construction: Logic Card Wire Wrap 2
Continuing on with the wire wrapping for the ALU logic card next up is the input and result links: Given the limited range of colours I’ve got to choose from (Black, …
12 Dec 2013 - 1 min read
ALU Construction: Logic Card Wire Wrap 1
Finally, with all the soldering now done, it’s time to set about wire wrapping the ALU logic card. First up is the internal connections within each logic bit: After wire …
10 Dec 2013 - 2 min read
ALU Construction: Logic Card Power Rails
It seems that every time I move on to the next stage of construction on the ALU logic card it’s fiddlier than the stage before it … this stage is no exception. …
09 Dec 2013 - 2 min read
ALU Construction: Logic Card Relay Sockets
The construction of the ALU logic card is coming along nicely but there’s still a lot of soldering ahead to get all the relay sockets down … and this part is the …
08 Dec 2013 - 1 min read
ALU Construction: Logic Card Header Pins
Following on from the successful construction of the first bit on the ALU logic card in my last post it’s now time to start putting together the other 7 bits and the …
07 Dec 2013 - 2 min read
ALU Construction: 1-bit Logic Full Construction
So, although I probably should construct the logic card methodically a full stage at a time (solder header pins then sockets then wire wrap) I can’t resist fully …
06 Dec 2013 - 1 min read
Following on from my last post I can now test the LEDs that have been soldered and hooked up to the header pins on each of the three ALU cards (Logic, Arithmetic and Control). …
06 Dec 2013 - 1 min read
ALU Construction: Logic Card Wire Links
Before I can test all of the LEDs laid down so far (to make sure they survived the heat of the soldering iron) I need to add some wire links on the logic card between the LED …
05 Dec 2013 - 3 min read
ALU Construction: LED Header Pins
So far, in the construction of the three ALU cards (Logic, Arithmetic and Control) I’ve soldered down the connectors and LEDs. It’s now time to solder in some …
02 Dec 2013 - 4 min read
ALU Construction: Connectors and LEDs
As promised in my last post it’s finally time to get the soldering iron out and make a start on constructing the three cards that make up the ALU. I’m going start …
01 Dec 2013 - 4 min read
In the last three posts I introduced the design for the 3-to-8 Function Decoder, Zero Detect circuit and the Condition Registers. In this post I’ll put all three of …
30 Nov 2013 - 4 min read
ALU Design: Condition Registers
This post covers the design of the ALU Condition Registers which along with the 3-to-8 Function Decoder and Zero Detect circuit (both covered in my previous posts) make up the …
23 Nov 2013 - 2 min read
This post covers the design of the Zero Detect circuit which along with the 3-to-8 Function Decoder (covered in my last post) and the Condition Registers (next post) make up …
20 Nov 2013 - 2 min read
This post covers the design of a 3-to-8 Function Decoder which along with the Zero Detect circuit and Condition Registers will all go in to the ALU Control Card. The Decoder …
17 Nov 2013 - 5 min read
ALU Design: 8-bit Arithmetic Unit
In the last post I introduced the design for the 1-bit Arithmetic Unit. This post covers connecting eight of these units together to make an 8-bit Arithmetic Unit along with …
15 Nov 2013 - 3 min read
ALU Design: 1-bit Arithmetic Unit
This post covers the design of a 1-bit Arithmetic Unit that can add two input bits together (B and C) with carry in and out. Here’s a schematic of the 1-bit Arithmetic …
13 Nov 2013 - 5 min read
In the last post I introduced the design for a 1-bit Logic Unit. This post covers the design effort to cram 8 of these on to a single pad board complete with connectors, …
11 Nov 2013 - 5 min read
This post covers the design of a 1-bit Logic Unit that can produce AND, OR, XOR, NOT and SHL (Shift Left) outputs from two input bits B and C. Here’s a schematic of the …
07 Nov 2013 - 4 min read
Architectural breakdown: the ALU
In this post I’ll continue to try and explain away the various bits of the architecture that will make up my relay computer project — this time it’s the Arithmetic …