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Some 8-bit stuff - Printable Version

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Some 8-bit stuff - phyrrus9 - 10-01-2018

So, I've been collecting electronics components for the last month so that I could design and physically build myself a small CPU. I finally figured out an instruction set I want, and got to work today on the ALU. The instruction set is as follows:

Code:
Registers: R0-R9 R7 is stack pointer R8 is link register R9 is program counter ALU ops (reg-reg): ADD SUB NEG INV LSH RSH AND ORR XOR MOV (also accepts constant) CMP (also accepts constant) mem: LDR STR PSH POP other (either constant or register): BRA JMP INP (register only) OUT

And, just because it looks pretty, here's a graphic of the schematic for the ALU instructions:

[Image: Cc1SmWi.jpg]


Let me know what you guys think. So far, the bill of materials is just under $30. When finished, this might be a fun project for those of you that want to learn this stuff (ill release my schematics if people are interested)

RE: Some 8-bit stuff - Losi - 10-01-2018

Holy shit that's cool. Quite an ambitious project i'd have to say. Keep us updated!

RE: Some 8-bit stuff - Cr3aTor - 10-01-2018

That's a nice project, I might give it a try.
Good job and thanks for sharing.

RE: Some 8-bit stuff - Jimbo39238 - 10-01-2018

That is awesome dude, the schematics would indeed be cool Tongue

RE: Some 8-bit stuff - phyrrus9 - 10-01-2018

(10-01-2018, 04:22 AM)Cr3aTor Wrote: That's a nice project, I might give it a try.
Good job and thanks for sharing.

I encourage you to do so. The difficulty with something like this isn't the design, it's the optimization. With a basic understanding of digital logic you can build your own without issue.

RE: Some 8-bit stuff - Cr3aTor - 10-01-2018

(10-01-2018, 03:10 PM)phyrrus9 Wrote:
(10-01-2018, 04:22 AM)Cr3aTor Wrote: That's a nice project, I might give it a try.
Good job and thanks for sharing.

I encourage you to do so. The difficulty with something like this isn't the design, it's the optimization. With a basic understanding of digital logic you can build your own without issue.

I'm actually thinking of a series based on my journey into electronics and this project would most probably be part of it.

RE: Some 8-bit stuff - OversouL - 10-01-2018

I'd like to see more posts about this project. It will be an interesting read. I already forgot my computer architectures class and it will be interesting for me if you show how you designed this from the start. Biggrin

RE: Some 8-bit stuff - zorrophreak - 10-02-2018

Looks pretty sexy my dude, I'll brush up on 8bit shit soon and I'll give this a shot with you!

RE: Some 8-bit stuff - phyrrus9 - 10-02-2018

(10-02-2018, 05:27 AM)zorrophreak Wrote: Looks pretty sexy my dude, I'll brush up on 8bit shit soon and I'll give this a shot with you!

I expect to see some decoder logic soon. You're looking at a completed ALU!

RE: Some 8-bit stuff - phyrrus9 - 10-03-2018

An update for you guys. I decided to run a test and see how difficult it would be to do it using surface mount components and printed circuit boards. Here's the drawings from that: I drew up the ALU/XOR circuit

Schematic:
[Image: d27PO9E.png]

Gerber, all layers
[Image: npPdgSp.png]

Mock up (top side)
[Image: VXhhfSB.png]

Mock up (bottom side)
[Image: uV4SUeR.png]