An 8-bit computer based around an AVR ATMega-644 and junk-box SRAM.


I’m am going to make a series of posts in the build log, showing from the beginning of the project, what has happened.  I’ve collected notes and pictures along the way, and I will be presenting these in a time-compressed manner.

Why another computer?

I have been playing around with computers since a young kid.  One of the first computers I played with was the Commodore Vic-20.  It was very limited in its abilities, but it was a start.  I eventually got into PCs, and now I’m a software enginner.  I’ve also been very interested in electronics.  For a long time, I’ve been wanting to build my own computer.  In college we simulated computers in FPGAs; that’s probably the closest to realizing my own computer design in hardware.

real-time update

Next steps:

Ethernet:  I want to connect to the internet, without the ‘help’ of a PC.  There seems to be two main options: the wiznet chips (like the W5100) and the Microchip ENC28J60

Both use the SPI bus.  The ENC28J60 is very simple, so the burden of the TCP stack is pushed into my code:  I have to do it or find a library.  There are libraries out there, but limited abilities.  The Wiznet chip does the TCP stack itself, leaving me with more-or-less a serial interface; once the socket is up I just send/recv bytes to the thing.  I was also tempted by the simplicity of a device such as the wiz110sr, which just IS a serial port that connects to a socket.  I would put it in a seperate box, call it a ‘modem,’ and get on with my life.  


So, I will be using the Wiznet 5100 chip, for now.


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