brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell

9Sep/111

Intel 8080 CPU Emulator (in Javascript, no less)

After getting a version of Tiny BASIC running on my emulator, I was scanning around to try to find something else to run. And, of course, when you look, you find all sorts of cool stuff. I happened across this cool page which is an 8080 emulator which is written in Javascript, and runs entirely in the browser. Very neat.

Intel 8080 CPU Emulator.

Filed under: Emulation 1 Comment
9Sep/110

Emulator progress, and envy…

I've made a tiny bit of headway, but also encountered a link which makes me envious of much greater hacking skill. Óscar Toledo did an 8080 emulator that can boot CP/M as part of the 19th International Obfuscated C Code Contest, winning Best of Show. Its brevity is the "soul of wit". Check it out.

Toledo 8080 emulator

Óscar also has written several tiny chess programs, and a Javascript chess program. Awesome.

While I didn't find his code to be all that helpful (it's, well, dense to say the least), I did find his approach to be helpful. A few additional minutes of hacking, and I managed to get the Tiny BASIC that he runs on his simulator to work on my own. Witness the following BASIC program:

>LIST
  10 PRINT "A PROGRAM TO EXPLORE THE 3 * X + 1 PROBLEM"
  20 FOR I = 1 TO 10
  25 T = I 
  30 GOSUB 100
  35 PRINT
  40 NEXT I
  50 STOP
 100 PRINT T,
 110 IF T = 1 GOTO 1000
 120 LET J = T / 2 
 130 IF 2 * J # T GOTO 140
 135 LET T = J
 136 GOTO 100
 140 T = 3 * T + 1 
 150 GOTO 100
1000 PRINT
1010 RETURN

OK
>RUN
A PROGRAM TO EXPLORE THE 3 * X + 1 PROBLEM
     1

     2     1

     3    10     5    16     8     4     2     1

     4     2     1

     5    16     8     4     2     1

     6     3    10     5    16     8     4     2     1

     7    22    11    34    17    52    26    13    40    20    10     5    16     8     4     2     1

     8     4     2     1

     9    28    14     7    22    11    34    17    52    26    13    40    20    10     5    16     8     4     2     1

    10     5    16     8     4     2     1


OK
>

Not bad! I suspect that even though my 8080 simulator is still pretty rough, I could get CP/M booted on it in much the same way that he did. More later.

Filed under: Emulation No Comments