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C64 - A reappraisal 2017


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#326 carlsson OFFLINE  

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Posted Today, 4:36 PM

So in the best of worlds, Atari might've been both the company "causing" the video game crash, and "fixing" it a little later with a new generation of game systems, perhaps before Nintendo came along (and Atari's potential licensing of the NES if it wasn't for the ADAM Donkey Kong yadda yadda).



#327 Nebulon OFFLINE  

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Posted Today, 5:08 PM

I'm familiar with history documented at http://www.atarimuse...ld/1450xld.html

 

I'm making the assumption Atari without Jack would have keep the 1450XLD but instead of using FREDDIE use the Amiga chipset.  And an obvious follow on would be a 68K processor with the Amiga chip set likely called a new name or something like the 1600ST ( ST for sixteen/thirty two).

 

http://www.atarimuse...les/mickey.html

 

"one was designated the Atari 1650XLD which would have been 6502 CPU based, the other was the Atari 1850XLD which would have been based on the Amiga Lorraine."

 

 

Amiga OS is 32-bit so (assuming Atari also opted for a 32-bit OS for the 1850XLD) that means the 6502 version would have to have a different OS written for it.



#328 thetick1 OFFLINE  

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Posted Today, 6:41 PM

 

http://www.atarimuse...les/mickey.html

 

"one was designated the Atari 1650XLD which would have been 6502 CPU based, the other was the Atari 1850XLD which would have been based on the Amiga Lorraine."

 

 

Amiga OS is 32-bit so (assuming Atari also opted for a 32-bit OS for the 1850XLD) that means the 6502 version would have to have a different OS written for it.

 

OK that is exactly what I wrote I just used the wrong historical names. No reason why a 6502 based processor could not be used with a modified Amiga Lorraine chipset.   It is bit ridiculous to argue hypothetical possibilities though.  

 

Actually the 68K processor implements a 32 bit instruction architecture but a 16-bit data path to external components.  Thus why Atari chose name Atari ST ( Sixteen/ Thirty two).  So depending how you define a 32-bit machine the 68K based  Amiga or Atari ST is either a 16-bit or 32 bit machine.  The original Amiga OS clearly supports the 32-bit instruction architecture but only 16-bit external data architecture.


Edited by thetick1, Today, 7:22 PM.


#329 Bryan ONLINE  

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Posted Today, 7:06 PM

The 1650XLD was rumored to have an Intel chip for DOS compatibility.

 

Sure, the Amiga chipset could be modified for 8-bit systems but what good is Amiga hardware in a system that can only see 64K without bank switching? A 320x200x16 color screen is 32K just by itself. Once your graphics get big, you need a big address space.

 

Who knows what Atari would have done if the crash hadn't happened.  They sure wasted a lot of money exploring all the possibilities.



#330 Bryan ONLINE  

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Posted Today, 7:32 PM

Only a little bit on topic...

 

I would love to have a crowdfunding campaign to design an 8-bit system from the ground up. Design the NMOS chips and everything using ONLY technology from around 1980 (if there's not enough money for chips, then workalike FPGA DIP's could be used in the board). It would be fun to deliver boxed computers from an alternate history, but based on the architecture ideas we'd most like to see in a single machine.

 

Then we'd write a fictional backstory for the machine and its parent company.



#331 fujidude OFFLINE  

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Posted Today, 7:57 PM

If your urine glistens in all the colours of the rainbow, perhaps you should see a doctor?

 

Nahh, it's what every true computer fan should strive for!



#332 VladR OFFLINE  

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Posted Today, 8:50 PM

Sure, the Amiga chipset could be modified for 8-bit systems but what good is Amiga hardware in a system that can only see 64K without bank switching? A 320x200x16 color screen is 32K just by itself. Once your graphics get big, you need a big address space.

Unfortunately, this problem certainly didn't stop the Jaguar. What good is it to me that it can address 2 MB, if the GPU is fricking four kilobytes ?

- And it doesn't support stack, so you gotta reserve some space for emulating stack.

- And every variable you use is 32-bit integer (otherwise you fall down to 68000 performance levels once you start extracting separate bytes from those 32 bits, or if you load from main slow RAM),

- thus you burn through those 4K almost instantly

- you fit much less code than on 6502, as you don't have 8-bit instructions like INX/INY/CLC, they're 16-48 bits (2 - 6 Bytes)

- don't get me started on how the GPU performance gets butchered once you start splitting&blitting code chunks to the cache using the infamous 64-bit blitter mode...

 

If I had it my way, I'd rather limit jaguar to 64 KB bank-switching (like on 6502) from those 2 MB, but have those 64 KB for GPU cache. This alone would incredibly upgrade the performance capabilities. If Atari 800 is able to switch banks within 1-2 cycles, I for sure wouldn't mind those cycles if ObjectProcessor would switch to a different bank for each bitmap it processes and displays.

 

Besides, the memory controller in Jaguar burns few cycles anyway upon crossing the 64-KB boundary, so again - what good is it then again (other than for hibernated-turtle-slow 68000 code)? It only appears as a linear 2 MB system (and only for the arguably hypothetical corner case of 68k coding), but at a significant performance cost the moment you start crossing the 64 KB boundaries with your data (which can be very easily tested).

 

I would love to have a crowdfunding campaign to design an 8-bit system from the ground up. Design the NMOS chips and everything using ONLY technology from around 1980 (if there's not enough money for chips, then workalike FPGA DIP's could be used in the board). It would be fun to deliver boxed computers from an alternate history, but based on the architecture ideas we'd most like to see in a single machine.

Eclaire XL is attempting something similar, though obviously not to the degree that you want (via FPGA). But I hear ya and agree.

 

I don't believe we'd be able to find a hundred people, though...

 

 

 

A 320x200x16 color screen is 32K just by itself. Once your graphics get big, you need a big address space.

No, you don't. Now, it may be more convenient from coding perspective, but you don't really need it.

 

I'm going to see soon myself, as I'll be working with Eclaire's 4x Antic modes (e.g. 320x192x16), but basically the rasterizer needs to be able to work in zones and access one zone at a time. There's some overhead, of course, but same technique has been used at original XBOX where they had to split rendering in certain gfx modes into zones.

 

Besides, one bank is 16 KB, so we're talking only 2 banks here anyway, so the overhead will be minimal and highly likely masked by fake clipping (e.g. it costs the same amount of cycles whether I clip against scanline 96 or 192 - does the rasterizer really care if that scanline is the last one in bank one or two ? I could ask, but suspect I know the answer to that already :) ), thus very likely - free.



#333 Deteacher OFFLINE  

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Posted Today, 9:04 PM

Me, personally, I love both machines.  I've always thought the Atari had better sound (4 channels, vs. C64's 3 channels) but games on the C64 look better.  Also, like the OP said, there are some games that were strictly for the C64, like Space Taxi and Dino Eggs.

 

I prefer the Arcade ports on Atari.  Pac-Man, DK, etc. are so much closer to the arcade than the C64 versions.  However, the C64 versions of Ultima III and IV have the soundtracks, which the Atari versions are sorely lacking.

 

All in all, I can't pick one over the other.  Everyone should own both.  :)


Edited by Deteacher, Today, 9:15 PM.


#334 Bryan ONLINE  

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Posted Today, 9:16 PM

Unfortunately, this problem certainly didn't stop the Jaguar. What good is it to me that it can address 2 MB, if the GPU is fricking four kilobytes ?
- And it doesn't support stack, so you gotta reserve some space for emulating stack.
- And every variable you use is 32-bit integer (otherwise you fall down to 68000 performance levels once you start extracting separate bytes from those 32 bits, or if you load from main slow RAM),
- thus you burn through those 4K almost instantly
- you fit much less code than on 6502, as you don't have 8-bit instructions like INX/INY/CLC, they're 16-48 bits (2 - 6 Bytes)
- don't get me started on how the GPU performance gets butchered once you start splitting&blitting code chunks to the cache using the infamous 64-bit blitter mode...

 
 Yeah, I was a Jag developer for a short while. It was an ambitious design slaughtered by the need to keep it all really cheap (and by insufficient hardware testing). Even though you could do some fast things with it, nobody in the game industry has got the time to figure out how to squeeze every last ounce of performance out of a complicated architecture. Especially if the docs are sparse.
  

No, you don't. Now, it may be more convenient from coding perspective, but you don't really need it.

 

Well, when you saddle a 6502 with a screen that big you've got two problems:

 

1. Most of your RAM will be consumed with graphics. Double buffering will consume all of it.

2. It's slow to update large bitmaps with a slow processor. This is one of the things that hurt the Apple IIgs. It had modes like an ST, but couldn't draw anywhere near as fast.



#335 thetick1 OFFLINE  

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Posted Today, 9:23 PM

 
 Yeah, I was a Jag developer for a short while. It was an ambitious design slaughtered by the need to keep it all really cheap (and by insufficient hardware testing). Even though you could do some fast things with it, nobody in the game industry has got the time to figure out how to squeeze every last ounce of performance out of a complicated architecture. Especially if the docs are sparse.
  

 

Well, when you saddle a 6502 with a screen that big you've got two problems:

 

1. Most of your RAM will be consumed with graphics. Double buffering will consume all of it.

2. It's slow to update large bitmaps with a slow processor. This is one of the things that hurt the Apple IIgs. It had modes like an ST, but couldn't draw anywhere near as fast.

 

All true but I thought I typed modified Amiga chipset which would imply a coprocessor to handle the additional resources needed for the improved graphics.  The economics might not make sense as it might be cheaper just use a 68K then a 6502 (more likely 65816 ) with an added coprocessor with the Amiga chipset.  


Edited by thetick1, Today, 9:29 PM.





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