Bentium Pro ALU: Overview, Registers, Adder, Logic, Shift/Rotate and Schematics
My Bentium Pro computer is a Ben Eater inspired machine which uses many of the same ideas and many identical or very similar circuits. My intention with these blog posts was to write about the things I have added or done differently and leave the same/similar stuff for people to copy from Ben. I also …. Read More
The Bentium Pro Flags Register
After giving you a general tour of the ALU of the Bentium Pro and the carry select circuitry I want to move onto describing the flags register and how the flags are evaluated. As a reminder, the Bentium Pro has four flags: Carry. This can contain the carry/borrow from the adder and also the bit …. Read More
Breadboarding With Diode Logic
I was thinking recently about OR gates. We normally do these with TTL logic chips but I wondered whether it would be possible to do the same thing with diodes. A quick Google showed that this was not merely a workable idea but something which has a name – ‘diode logic‘ – and which has …. Read More
Adding ADC, SBC, INC & DEC Operations To Ben Eater’s ALU
The ALU on Ben Eater’s original Bentium 8-bit computer has two operations: add (ADD) and subtract (SUB). This gives his design the ability to add and subtract 8-bit numbers. But if you want to add or subtract larger numbers then you need more than 8 bits. You could do this by expanding to a 16-bit …. Read More
My Breadboard ALU With Twenty Operations
Last year I built Ben Eater’s 8-bit breadboard computer, which taught me a lot about how processors work. But with only 16 bytes of memory it’s not really usable for any kind of real world tasks. As soon as I’d finished it I knew I wanted to make some upgrades. And when I looked at …. Read More
HDSP-0762: Hex Displays Made Easy
If you’re working (or playing) with digital electronics then you’ll probably want to display your data data on hex displays at some point. Normally this involves using some kind of decoder to turn your data into something that can drive a 7-segment display. Which means extra chips, extra wires and extra breadboard space. I set …. Read More