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Chris
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6800 Systems
Post Posted: Wed Dec 29, 1999 4:05 am
Today at my local programming spot (Explorer Post 227) I
was talking with one of the advisors about assembly and processors. He was giving me some really
interesting insight on how it works and he assigned me 2 projects that I could choose to work
on to improve my programming skills:

1) An Assembler in any language I chose
2) An Emulator in any language I chose

He also told me about the motorola 6800 which was around the same time as the Z80, 6502,
and 8080 processors. He said that the 6800 would be the processor of choice for myself, being
a casual programmer, for it's simplicity. Personally, I don't want anything thing to do with the
Z80 right now and I would like to try something new. I'm going to choose option #2 which is
to write an emulator but I don't have any good documentation and I would like to know what
kinds of systems use this type of processor.

Yes, I know this message has absolutely nothing to do with SEGA emulation but I know you all
can be very informative and give me "moral" support.

Happy holiday and have a great new year,

Chris :o)
 
  • Joined: 28 Sep 1999
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Post Posted: Wed Dec 29, 1999 6:49 pm

Quote
> Z80 right now and I would like to try something new. I'm going to choose option #2 which is
> to write an emulator but I don't have any good documentation and I would like to know what
> kinds of systems use this type of processor.

The MAME project (www.mame.net) has a 6800 emulator written in C that
might be a good reference. I would assume most all information pertaining
to other CPU's in the 6800 family, such as the 6809, would be valid for
the 6800 in some way.

You can order product literature from Motorola for free, with
minimal shipping costs if you live outside the USA. I don't know
if they have manuals for the 6800, but they definetly have them
for the 6809 (ordered one myself a while back)

Personally, I think writing a 6502 emulator would be a bit easier,
because there's plenty of documentation and 6502 programs for you
to test with. And the 6502 is fairly simple, apart from some
unusual bits with addressing modes and zero page stuff.
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Chris
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Post Posted: Wed Dec 29, 1999 11:44 pm
Man, the 6502 is what I've been wanting to work on for the past 8 months. It's gotta be one of the
simplest processors out there. Hell, my original goal before all this SMS crap was to write an NES
emulator. But I figured since there were around 60 or so floating around the net that I would quit
and give a shot to SMS emulation. But that processor, the Z80, is so tedious. With all those registers
there's like 600 or 700 instructions to emulate. Not to mention all the memory crap. The 6502 only
has 150 or so of instructions and there's only the A, X, Status, Stack, and Program Counting registers.
I had a pretty functional 6502 emu under VB but it was slow. If I did an internal loop, the entire
program would freeze until that loop was broken and if I used the VB timer control it was god
forsakenly slow! It was more of a 6502 debugger. You could load the NES game, divide the
program and video roms, and execute the program rom while at the same time giving you
a constant update of where the PC was and what the CPU was doing. I wanted to port it
over to Visual C++ but I'd have to learn that first. I don't know what I want to do. It's times
like this when I want to just say fuck it, shut this piece of mechanical shit down, and go
bowling.

Chris :o)
 
Nyef
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Post Posted: Thu Dec 30, 1999 1:44 pm
Quote
> over to Visual C++ but I'd have to learn that first. I don't know what I want to do. It's times
> like this when I want to just say fuck it, shut this piece of mechanical shit down, and go
> bowling.

Then may I recommend you shut the computer down and go bowling? ^_^

Quote
> Chris :o)

P.S.: If you don't want to do another NES emulator, there are tons of other systems that use the
6502. Atari 2600 comes to mind, as do the Apple ][. the Vic 20, the C64, and the Atari 400.

--Nyef
 
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Post Posted: Fri Dec 31, 1999 8:01 pm
Quote
> Man, the 6502 is what I've been wanting to work on for the past 8 months. It's gotta be one of the
> simplest processors out there. Hell, my original goal before all this SMS crap was to write an NES
> emulator. But I figured since there were around 60 or so floating around the net that I would quit
> and give a shot to SMS emulation. But that processor, the Z80, is so tedious. With all those registers
> there's like 600 or 700 instructions to emulate. Not to mention all the memory crap.

What memory crap?

Quote
>The 6502 only
> has 150 or so of instructions and there's only the A, X, Status, Stack, and Program Counting registers.

And sometimes 'y'?
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