The 8-bit computer is up and running! Check out my blog posts on the computer: http://blog.ircmaxell.com/search/labe...

Before you see my arm come in, you will see about 11 clock cycles across 2 instructions prior to me turning up the frequency.

The first instruction copies the B register to the A register (upper center of the screen). This causes the A register to change from 00000001 to 00000010.

The second instruction copies the C register to the B register. This completes just as I increase the clock speed.

The initial clock is about 1 htz (one clock pulse per second). The end I haven't measured yet (waiting for test hardware to arrive).

The program is simple. Count the Fibonacci numbers up from 1, 1 all the way until the value overflows (can't fit into 8 bits). You see clearly 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233 appear in the A and B registers. Then the computer restarts the sequence.

What's happening is the following program (intel assembly syntax):

fibo:
MOV RA, 0x01;
MOV RB, 0x01;
fiboLoop:
ADD RC, RB;
JMPC fibo;
MOV RA, RB;
MOV RB, RC;
JMP fiboLoop;

The "A" register is hard-wired as a second input to the ADD instruction. So ADD RC, RB; is really saying RC = RA + RB;