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Since command blocks are great, I have been making a 4 bit CPU based around command block logic. Using testforblock and setblock in vanilla, I was able to so far create on a basis for a CPU with 4 usable registers, 2 temp registers, resiable program memory, 3 internal commands (ld d,r[f], ld r[f],d, inc pc), and one user op (ld r,imm).

Registers Left-to-right: User registers a, b, x, y, temp register d for internal commands, temp register f for flags to internal commands.


Program memory. Has ld a,6 (00nn / nnrr)


Instruction decoder is first two command blocks (00xx is ld r,imm), next 2 are block copies that move xxnn to d, next lone command block calls inc pc, next 4 block copies move nnxx to d and xxrr to f, next block calls read, last block calls inc pc.


internal commands' calling blocks and f register decoders in front.


back of internal commands.


Other op codes will just be added to on the decoder chain. Op codes include
Code:
ld r,imm Register load
ld r,r Register copy
in p  IO input to port #p
out p IO output to port #p
bz n  Branch if a == 0
cmp.t r Compare r with a using mode t (eq, neq, gt, lt), store result in a
add a,r
sub a,r
or a,r
and a,r
xor a,r
(inc/dec or rotates?)


<edit>I made a fast full adder (testing, not added to the CPU yet) that is 5 to 9 ticks per slice, depending on the logic.
Made a 4 bit full adder (add a,r) into the CPU, so far it works fine. Next for a not instruction and I will have subtraction.



<edit>

Ran a bunch of programs, works well, although slow. I wasn't aiming for speed, but this seems pretty fast for being unoptimized. Sample:
Code:
(a == 0)
ld b,0b0011
ld x,0b1100
ld y,0b0001
add a,b
add a,x
add a,y
(a == 0)
Hi,

Is your CPU "world" available for download ?

I'm currently playing with the "Commandore 32", to see how he's used the command blocks.

Before that I spent a lot (too much !) of time playing with RedStoneChips (on bukkit). I built a large part of a virtual CPU, but then got "stuck" trying to figure out how to make a micro-coded control section.

One of the only (*the only ?*) good examples I found of how to make a simple micro-code control unit was "Warren's Microcoded CPU" (made in Logisim).

I never made anything substantial with "raw" redstone, didn't have the patience to create a "bazillion" flip flops Wink

Mike
Yes, can you please put your world up for download?

I've been wanting to make a command block computer for months. It has been among my most important projects occupying my scarce free time. And until now, I thought that nobody had ever made one before in vanilla Minecraft and without programming from outside Minecraft (like Commandore 32). I see I was mistaken.

I would be very interested to look at your computer architecture. You would be doing everyone a favor to post your world.
> without programming from outside Minecraft (like Commandore 32)

Commandore is vanilla Minecraft.

The "outside Minecraft" is just for the compiler, which produces [ /scoreboard players set XX ] "Assembly language statements".

But as I look at it, so far, the command blocks don't seem to have made it that much smaller (if at all) from the usual vanilla-redstone computers. There still seems to be a large amount of "torch circuitry" in it.

Mike
  
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