Guys, guys.... I have one thing that you lot dont, a school tech LOL

He said:

"Just draw out your circuit and I will print it "

But I have decided to do a mix of wire wrapping and pcb. The PCB will be single sided only and the wire wrapping will be used when i cant get all the connections to work!!!

 

Interesting project. Have you study the Intel 4004 and Intel 4040 internal architecture ?

 

Kind of...

WHERE CAN I GET OLD CPU's AND CHIPS!!!!
They are simple and a good form of computer education for me

 

Many of the old CPUs like Z80 are still sold today. I guess it is hard to find a 4004 or 4040 on sale today. But I think you can find the code needed to program a FPGA so it emulate a virtual CPU, for many 4 and 8 bits CPUs.

 

alu sketch

 

The old 6502 is alive and well, and you can still by vintage computers (such as Commodore 64) for a song. Better yet, you can get emulators for almost everything, which allows you to try your hand at coding the old stuff without having to buy anything. Some of the Commdore emulators are truely fantastic.

Ever hear of a Sinclair Computer? The design was bought by Timex, it had 5 chips total, this included the Z80 and a voltage regulator, and had a old NTSC video signal out. PITA to program, as the power supply kept popping out (they saved a bit too much money on the earphone jack), but the concept was truely awsome.

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I just occured to me, though I don't know how true it is, that the 4004 instruction set is buried in the 8080 (and probably the Z80) CPU. These chips evolved from the previous, and the great grand daddy of them all was the 4004. You might think about seeing if an existing 8 bit chip can be scaled back and treated like a 4 bitter.

 

It is a shame that the "Visible 6502" program is not to be found any longer. The screen had all the elements of the processor laid out, and you could tell it where to start executing code. It was the slowest imaginable debugger.

Searches on "visible z80" and "visible 8051" come up dry, too.

The program was very instructive, as the program showed how the clock controlled all program execution.

 

Oshonsoft have some nice simulators.

 

I remember I used a CPM simulator running under dos. This because the Z80 simulator (I can not remember the name) I liked best was running under CPM. In those day we did not have flash. So it was somewhat irritating running out of blanked EPROMS. Well just a trip along memory lane

 

Some further poking around turned up some info on 6502's. It's obsolete, but has fewer registers, making the internal process easier to follow - http://richardbowles.tripod.com/cpu_sim/lessmenu.htm

 

Hi guys, IM BACK AND BETTER!!!

I am so sorry for not updating.
So anyway, guess what....come one......dont know....ok

My project has gone through the roof like you cant believe. What started out to be a project that was only really ment to do a few functions now does a wapping 16 instructions

But you can wright programs, load programs and a few more. Bellow is the finished code:

0000 - add (adds two numbers and stores in accumulator)
0001 - adm (adds number in accumulator with word B)
0010 - sub (subtracts two numbers and stores in accumulator)
0011 - sbm (subtracts number in accumulator with word B)
0100 - AND (AND operation with word A and B, then stores in accumulator)
0101 - ANM (AND operation with accumulator and word B, then stores in accumulator)
0110 - OR* (OR operation with word A and B, then stores in accumulator)
0111 - ORM (OR operation with accumulator and word B, then stores in accumulator)
1000 - NOT (NOT operation with word A then stores in accumulator)
1001 - NOM (NOT operation with accumulator, then stores in accumulator)
1010 - EXO (EXOR operation with word A and B, then stores in accumulator)
1011 - EXM (EXOR operation with accumulator and word B, then stores in accumulator)
1100 - COM (Compare Accumulator word with word B)
1101 - SAV (Saves words A, B and instruction into memory)
1110 - LOD (Loads words A, B and instruction)
1111 - RES (Resets everything)

Notice that it has an accumulator so you could write a program that gets a user defined input and does several things with it

Oh my god im so proud of this, ITS MY BABY!!!
The schematics will be released soon (once i have...er...debugged them?)
You get the idea!

Oh, and here is a picture of a visualisation with what it will look like and I have already built a keyboard (well, building almost finished) for it!!!

 

Good for you for seeing it to completion.

Imagine what the inventors did back in the 1940's and 1950's when nobody had any idea of what a computer might actually be, or how to construct the logic elements (vacuum tubes are not really happy as switches).

 

Yeah, this is what it would have been like:

inventors:
"WE HAVE BUILT THE WORLDS FIRST COMPUTER"

public:
"What is a computer?"

inventors:
"It can do addition, subtraction and many other math problems for you in a second"

puble:
"What ! That can do MY JOB FOR ME.....KILL THE INVERTORS"

inventors:
"ahhhhhh"

And the computer was not seen for another 30 years

The end!