4 Bit Homemade Computer

[Freyaday]

Are you going to make your own keyboard or are you going to use a standard PS/2 interface?

[Ashbad]

no, that stuff is too complex for my point in this -- think of a PC from 1950, with 64 bytes of RAM and 2-4 bit ALU's.  That's what this is like

The goal is to make it completely out of household products

[Freyaday]

Does that include blue lobsters?
Lobster Abacus!

[Ashbad]

I should look in my fridge hmm, maybe to store data I can have lobster chunks and setting bits adds lemons to the lobster "bits" and to reset them you eat them.

I think I'll write up a decent ALU design later today, so I can do 4 bit math fast and with little wire

EDIT: and that "AND" machine is actually an "OR" machine -- sorry, I had my foot in my mouth

[Freyaday]

What are you going to do with the rest of the wire? Maybe you could use the lobsters for power?

[Ashbad]

I bet they give off more electricity than the electric eels I tried, so that would actually be a good idea

[Ashbad]

Well, after some fabulous input from runer, I have ideas for tons of different instructions and registers.  The opcode table is still far from complete, but I can explain the registers:

A - the primary arithmetic register.  Used in tons of instructions involving math and logic.  4 bit.
B - fulfills the role of A, less instructions support it, but its good for when A is tied up.  4 bit.
C - General use register, connected closely to the O output register for quicker transport of values for shipping.  4 bit.
D - General use register, connected closely to the I input register for quicker transport of values in shipping.  4 bit.
E - general use register, can be used to complement other registers to make 8 bit values. 4 bit.
F - flag register -- includes the C, Z, N bit flags and another general use bit used in more complex instructions.  4 bit.
G - (proposed, unsure if I'll keep it) includes more flags such as parity/overflow, and a few extra bits for really complex instructions.  4 bit.
I - input register, directly deals with the input received from a port in 4 wire form, transfers data quickly to D and slower to other registers.  4 bit.
O - output register, directly deals without the output sent out to a port in 4 wire form, transfers data quickly to C and slower to other registers.  4 bit.
PC$ - the program counter register, determines where in a 2048 bit program the instructions are to be read from.  8 bit.
PG$ - the page counter register, determines what page of a 256 page (each page 2048 bits) program instructions are to be read from.  Used in calculations and for easy management of pages without many ports -- however it relies on a port to actually swap pages. 8 bit.
N - the frequency register.  Directly deals with the speed at which a program can run.  The higher the number, the slower the program goes.  4 bit.
U8 - no use specified 8 bit register.
U16 - no use specified 16 bit register.
U32 - no use specified 32 bit register.
U64 - no use specified 64 bit register.

The no use ones can be accessed with a few more complex instructions, and can be used if you wanna use large numbers for some unknown reason.  Keep in mind, these would be very slow (unlike the other less used registers, which are really fast -- these are accessed in a different way than the others due to their size, with exception of A8 being connected like PC$ (fast) and PG$ (medium fast))



Edit: I just realized I should have some more, but I'm sure people will point out things like a double word one like HL and an offset one.  Give any suggestions
Edit2: and maybe another more general use one or two?

[Juju]

I love this idea to make a processor out of household items

[Ashbad]

Well apparently after telling my friend about the new and complex opcode table, he lost interest in making this completely out of household items

So, instead, I told him about logism, so we're gonna just fool around with that for now

So.... He says that if we just draw stuff up for logism, it should be around 64 bits... I said we should make a 4 bit processor first what do you guys think?

[ztrumpet]

Sounds like a cool project!  Good luck.

[Ashbad]

Thanks zTrumpet!  We'll try to make it the fastest 4 bit processor ever

[Happybobjr]

will you explain what you use for switches. Is it the magnets?
What are you using as a power supply?

[AngelFish]

*Cough* 64 bit is a pain to wire *cough*

You could shoot for 8 bit, though.

Also, completely ignore my tutorial if you'd like to make the next 4 bit i7

[Ashbad]

Thanks for that tutorial qwerty, it helped

[willrandship]

Interesting. I'm currently working on a base-4 2 bit processor, so it also has 16 commands. I have 4 addressing bits, though, so I can do a lot more with said commands BTW, 4 quaternary bits = up to 256 options

Sounds like a cool project! Mine's still in the design phase I've only managed some of the base circuits, like a multiplexer to choose the command, the memory, and the three base logic gates. XOR is not happening