Two Stop Bits | ddingus's comments

ddingus 751 days ago | parent | on: How can Space Invaders Invade Your Space? The Epoc...
Yet another odd little machine I have not heard of!
Very creative use of the hardware limitations.
Seems to me it must have lacked interrupts, or its video system must only respond to inputs once per frame. Maybe the CPU was too slow...
ddingus 758 days ago | parent | on: Microsoft's Xenix - Microsoft tries their hand at ...
Mine too, along with a UNIX shell Internet account.
ddingus 764 days ago | parent | on: Intel 8080 Emulator in 6502 Assembly
Interesting. What is the 8080 speed?
- chris8080 764 days ago
  Unless my calculations are wrong, executing a NOP (opcode $00) would take 39 cycles (instead of 4 cycles on a 8080).
  Here is a simulation of an execution of NOP from the label run_emulator in 8080.s with STACK_BASED_DISPATCHER=false (it's 6 cycles faster)
```
  (cycles, instruction)
  3 lda (PCL),y
  2 tax
  2 asl
  3 bcc do_tab1
  4 sta _jmp2+1
  4 lda instruction_length,x
  3 beq length1
  5 inc PCL
  3 bne no_inch_pch
  5 jmp (tab2)
  3 jmp run_emulator
  =39
```
  And that's in the best case with no page crossing.
  - chris8080 764 days ago
    errata: replace _jmp2 by _jmp1 and tab2 by tab1
    - ddingus 763 days ago
      Nice! I am looking at my Apple 2e with 16Mhz 6502 (actually '802) with 1Mb of fast RAM on the CPU card thinking it may run at useful speeds.
      S1
ddingus 765 days ago | parent | on: Atari announces first new Atari 2600 game in 30 ye...
A lot of the fancier homebrew games actually make use of a processor in the cartridge.
This one appears true to Atari roots. Probably an 8, maybe more kilobyte game, straight up use of the video hardware, no flicker, no crazy tricks.
Looks fun, creative.
ddingus 765 days ago | parent | on: IT’S A HUMBLE ‘SCOPE, BUT IT CHANGED OUR WORLD
I made many of the exterior wraps. Rvinyl is the material. 5052 alum with vinyl heat bonded to it.
ddingus 765 days ago | parent | on: [Ask 2SB] How to promulgate this site
Write your feedback to others here, then link it there.
Post stories here. Link them in high traffic discussions. Reddit is good. X can be good too.
Include this site in your tag lines, profiles.
Hey, greets retro fans! I love having our place here to gather and benefit from our collective works.
ddingus 767 days ago | parent | on: ChatGPT fixes 6502 ASM code using an uploaded scre...
I am impressed. Dave did a great job explaining how he uses the product.
So far, the handful of little programming snippet requests for python, 6502 ASM, and C have been very useful just as Dave suggests.
If one is learning a new language, or trying out programming a new kind of task, ChatGPT can be a big help
ddingus 768 days ago | parent | on: Atari Projects
I find myself visiting this site every so often when I feel like ramping up on retro goodness.
Would be great to see this simple idea applied to other systems.