20 Nov 2022 - 4 min read
Well, what a journey that’s been then … I started work on a clock for my relay computer back in May 2020 and today (20th Nov 2022) this post marks the end of it. …
01 Feb 2020 - 2 min read
As the clock struck midnight at the very end of 2019 I decided, over a glass of something sparkling, that I’d set myself a challenge to put out a series of six YouTube …
05 Jan 2020 - 1 min read
In my last post I covered off the full design for the decoder card so all that remains is to get it soldered up and tested. As before I’ve put a video together which …
21 Dec 2019 - 1 min read
In my last couple of posts I covered off the full design for the controller unit. As the PCBs have now arrived I can get on with soldering up the cards and giving them a test. …
20 Nov 2019 - 2 min read
In my last couple of posts I covered off the full design for the sequencer unit. With PCBs now safely arrived in the post I can get on with soldering up the cards and giving …
04 Mar 2019 - 12 min read
After years of using pad/prototyping boards to build my computer I’ve decided to switch things up a bit and have a go at making a custom PCB. The thinking is that it …
27 Mar 2018 - 4 min read
Auxiliary Control Construction
In my last three posts I covered the design of the auxiliary control unit which will ease entering and inspecting programs in the computer’s memory. With the design ‘in the …
16 Jan 2018 - 3 min read
Fetch and Increment - Construction and Test
This is a bit of a landmark moment … at least for the construction of my relay computer. For a long time now my blog posts have been leading up to the point where my …
07 Jan 2018 - 1 min read
In my last two posts I covered the construction of the upper and lower incrementer cards. The lower card is a 16-bit half adder and the upper card is a 16-bit register. …
30 Nov 2017 - 2 min read
I’ve covered the construction of the upper and lower memory cards in my last two posts … it’s now time to bring those two cards together to form the memory …
11 Nov 2017 - 3 min read
In my last couple of posts I’ve been slightly distracted by some ‘miscellany’ but now I return to form and crack on with constructing the program counter. …
06 Aug 2017 - 4 min read
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. …
24 May 2016 - 2 min read
It’s finally time to give all the cards created so far a test so I can check everything works together as expected. This represents quite a bit of a milestone as the …
01 Jan 2016 - 3 min read
Controller Construction: MOV-8, ALU and SETAB
So yea, it’s been a while since my last post … in fact it’s been just over six months. For some reason I decided I didn’t have enough to do in the …
08 Jul 2015 - 6 min read
Sequencer Construction: 8-cycle FSM
I’m just about at the half way mark now for getting the computer to operate the MOV8, ALU and SETAB instructions. The easier cards are out of the way now … time …
07 Jun 2015 - 3 min read
Decoder Construction: MOV-8, ALU & SETAB
In a change from prior form I’m combining the construction and testing of the next card in to a single post this time. Partly because this card is a nice easy one but …
16 May 2015 - 1 min read
Register Construction: Completed Instruction Register Full Test
Following on from my last post, and after popping in some relays, the instruction register is complete and looks like this: As usual I’ve put a video together that …
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. …
28 Jun 2014 - 2 min read
Register Construction: Completed A and D 8-bit Registers Full Test
The A/D Register card is now complete and looks like this: As usual I’ve put a video together that demonstrates this card in operation. This time I don’t show …
26 May 2014 - 2 min read
Register Construction: Completed B and C 8-bit Registers Full Test
The B/C Register card is now complete and looks like this: As usual I’ve put a video together which demonstrates this card in operation … firstly on its own but …
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 …
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 …
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 …
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 …
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 …
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 …
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). …
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 …