Tag Archives: 6502

Another Video!

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It’s done!

The TwitALU in it's entirety.

The TwitALU in all its glory..

It’s been a long time since we’ve posted but the TwitALU is finished! It has already been shown off at the University of Bristol Open Day and the DigiMakers event at At-Bristol (review).

After the break are a few videos and photos of the TwitALU in action!

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The 6502 ALU in 7400 Logic

After investigating the 6502, Jeremy and I discovered that this ancient processor was still a complex beast of a machine with lots of constituent components and some quirky ways of implementing some features (like the extensive use of gated registers on the output of each combination logic block). The complexity of the 6502’s ALU means that implementing it entirely in large relays is unrealistic. It would be large, costly and the power requirements would be immense.

7400 logic NAND

7400 logic NAND

Instead, we have decided to do what many other 6502 replica makers have done and construct the processor in 7400 logic first.  Continue reading

Introductions and the 6502 ALU

Before I tell you about the juicy guts of the 6502 microprocessor, let me introduce myself and tell you a bit about the people behind the project.

My name is Jaimesh Mistry and I am a fourth year Electronics and Communications Engineering student, studying at the University of Bristol. I’ve been ripping apart electronics and changing the way they work ever since I got my first RC car and went exploring in my dad’s crazy toolbox. These days I’m building all sorts of wacky projects with the skills I’ve gained at university – from  autonomous robots to central heating systems that you can control from your smart phone. Hacking consumer tech is one of my passions, so a project like this where we mix a range of technologies from a range of eras in computing is right up my street.

Jeremy Dalton completes our duo and is also an Electronic and Electrical engineer in training at the University of Bristol. Like me, he is into all sorts of software and hardware hacking, has ‘tweaked’ many a working thing until it stops working and we’ve successfully collaborated on a good few projects in the past. However, one of his growing passions is in dirty great power electronics and motor drives, which recently landed him on an episode of Channel 5’s Motor Morphers where he helped convert a two-tonne milk float into a rubber burning dragster!

Anyway, enough about us. As promised, I’ll walk you through the MOS Technology 6502, why we chose it over other classic processors and our simplified design for implementation in 7400/relay logic. Continue reading

The Beginning!

Welcome to the blog! This blog will be acting as a part project log – part project blog to document a project that aims to…

Design and construct a replica of the ALU found within the MOS Technology 6502 processor and interface it with the micro blogging service Twitter, allowing commands to be sent to it for arbitrary calculations and logical functions to be performed.

As the quote from the project specification says, the core goal is to internet connect the ALU from what is now an old but arguably very important processor in history that is still being used today. This will allow instructions that can be issued to either be as simple as integer additions, subtraction, multiplications and divisions or as complicated as we have time to allow the system to handle, with one of the eventual goals being to allow the (quite slow) execution of 6502 assembly instructions.

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