[geeks] Crackpot project, need some guidance

[Mark Benson]

Hi,

I just thought I'd let you guys know how my ongoing project was progressing.

Firstly I owe HUGE amount of thanks goes to a number of people here for your
helpful suggestions particularly the suggestion of the TECS book. It's great
if a little brief in places but gives a great skeleton to expand upon as well
as explaining the fundamental principles. The help and encouragement received
convinced me to donate some funds towards Bill's last 2TB hard drive. It's
things like this that make this community worth being part if *warm fuzzy
glow*.

So far I have built all the basic stuff in gate-level logic to play around
with it. I understand how fundamental items like bi-stable flip-flops, adders,
shift registers and have built up to memory registers and how memory arrays
work using addressing. I am in the process of lashing together my first ALU
(Arithmetic Logic Unit) using 1-bit building blocks. It only does AND, OR and
ADD/SUBTRACT but it's a decent starting point. I understand 2's compliment
math now (which previously I heard of but knew nothing about) too which makes
life somewhat easier!

I understand how microcode is built using a ROM memory addresses to lookup CPU
functions allowing more nemonic choices for machine code instructions . My
task after I've proven my ALU is to lash up a simple 16-bit CPU and build a
rudimentary machine code for it and see if I can add a couple of numbers
together then subtract them to get back to the same result. You'll probably
hear the cheers from over there if it actually works :D

This has been the single most enlightening project I've done in a very long
time.

--
Mark Benson

My Blog:
<http://markbenson.org/blog>
Follow me on Twitter:
http://twitter.com/mdbenson

"Never send a human to do a machine's job..."