[chbot] Gigatron a 7400-series TTL microcomputer
fleetwil at gmail.com
Thu Jun 24 11:10:41 BST 2021
There is a series on YouTube by Ben Eater where he builds a micro coded
8bit CPU using standard TTL. I have followed along and built my own
variation and upgraded memory to 256 bytes and designed a few other devices
that work with it, including a typewriter interface
I should bring it along next meeting if you want to check it out
On Thu, 24 Jun 2021 at 21:54, Charles Manning <cdhmanning at gmail.com> wrote:
> Hi All
> All this talk today of smaller computers led me to have a bit of a nosey
> into what's happening in the "crazy CPU world".
> Have any of you looked at this wee CPU?
> Apart from the ROM and RAM the whole thing is just 74xx logic - 36 74xxs
> in all (including the oscillator)..
> It is a very barebones - 8 bit CPU but with some interesting twists.
> * Each instruction is 16 bits - 8 bit instruction coding and 8 bits
> * 16-bit Harvard address space: 32kx16 ROM, 32k RAM.
> * 8 bit accumulator, X and Y registers.
> They have a software simulator for it that is less than 130 lines long.
> Let the small times roll!
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