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Were there any alternative OS or CPU cards for the 800?


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#1 x=usr(1536) OFFLINE  

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Posted Mon May 14, 2018 9:30 PM

This post had me wondering about something that had crossed my mind years ago, back when I still had my 800: were any cards ever released that replaced the OS card or CPU board?

 

I believe that there were a couple of different revisions of the 10K ROM, but that's not really the sort of thing that I'm thinking of - something more along the lines of a completely different OS, or a Z80 card for running CP/M, etc. would be closer.

 

These are items I don't remember ever seeing or hearing about, so if anyone knows of anything it'd be interesting to hear about them.



#2 BillC OFFLINE  

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Posted Mon May 14, 2018 10:24 PM

There were 2 different OEM CPU cards for the 400/800, the original used the standard 6502B, while the later version used Atari's custom 6502C(AKA Sally).

 

There is also the 400/800 Super Color CPU card by tf_hh, the later version includes Bryan's UAV video upgrade.

http://atariage.com/... 800 cpu card

 

Then there is the alternate OS card for the 800 called the Ramrod MMOS. I believe it's main purpose was for use with the Newell products, OSN/Omnimon/Omniview.


Edited by BillC, Mon May 14, 2018 10:36 PM.


#3 Rybags OFFLINE  

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Posted Tue May 15, 2018 12:40 AM

Aside from 6502B / C "Sally" variants the very early NTSC  boards had CTIA instead of GTIA.  Desirable entirely due to rarity, as Atari's service centres replaced C with G for free (?)

AFAIK non-existent combinations are Sally boards with CTIA by from the factory, and any PAL with CTIA.

Whether early PAL machines came with 6502B, I don't know but guess that they probably did.

 

From Atari themselves never anything aside from NTSC's OS-A and OS-B and the PAL-B OS.  The NTSC A revision is somewhat undesirable thanks to it's bugs.  The PAL-A revision is believed to not exist at all.

 

The Fastchip FP upgrade was a swapover for the stock 2K FP Rom so as a standalone product wouldn't have come with any other hardware replacements.



#4 sup8pdct OFFLINE  

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Posted Tue May 15, 2018 2:12 AM

Pal only ever had Rev A os.  To best of my knowledge, no Pal 400/800 had a 6502B.

 

James.



#5 Kr0tki OFFLINE  

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Posted Tue May 15, 2018 2:23 AM

Atari's service centres replaced C with G for free (?)

Only if during the warranty period; otherwise they would charge a whopping $62.52 for the service. Source, source.

The PAL-A revision is believed to not exist at all.

Actually it's PAL Rev. B that doesn't exist.

Edited by Kr0tki, Tue May 15, 2018 2:25 AM.


#6 Rybags OFFLINE  

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Posted Tue May 15, 2018 5:57 AM

I'm tempted to pull my 400 apart just to verify the Sally CPU theory - it was purchased sometime mid-late 1981 so the build date was probably late 80-early 81.



#7 rpiguy9907 OFFLINE  

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Posted Tue May 15, 2018 4:39 PM

Someone made a 6809 CPU board for them, but it was not a commercial product. Same for the 65C816 accelerators.

#8 kiwilove OFFLINE  

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Posted Tue May 15, 2018 4:57 PM

Only if during the warranty period; otherwise they would charge a whopping $62.52 for the service. Source, source.

Actually it's PAL Rev. B that doesn't exist.

 

I purchased an Atari 800 in London in Hammersmith Maplins - and before I left the UK to head home - I had it converted via Atari UK for use in New Zealand.  If my memory serves me correct? It may have been converted to PAL Rev.B???

 

I don't know what they did exactly to it.  Sadly I don't have that Atari 800 anymore...  The only difference between the TV standard in the UK versus NZ - is at that time - NZ did not have UHF frequencies operational - which started being used in the 90s?

So they would have changed the RF output so that a VHF channel would then be working?

 

Harvey



#9 luckybuck OFFLINE  

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Posted Tue May 15, 2018 5:19 PM

:-) Kr0tki has made for us the OS B PAL ROM :-))) I used it on daily basis and it works like a charm. :-) So, thank you again for.

 

On the other hand, there is the source code for B, but up to now (2018) we have never seen a real OS B ROM.

 

If you have one, please let us know. Only 2 ROMs are still missing. Further, please check in here:

https://www.wudsn.co...ROMChecker.html

 

and for the 2 ROMs here:

https://atariwiki.or...?page=Rarity 10



#10 Rybags OFFLINE  

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Posted Tue May 15, 2018 6:35 PM

UK used PAL-I which specifies a 6 MHz audio seperation instead of 5.5 used by PAL-B/G.

 

A device will work fine from one to the other but there'll be no audio.  More modern TVs have the full digital tuning and country select on the menu so would likely be OK with it.

VHF or UHF shouldn't matter.

Most older TVs do VHF and UHF - whether a computer does VHF 1 or UHF 36 doesn't matter much in this area though isn't VHF less common on UK sets?

Likely the modification needed was to either replace the RF modulator or substitute components to produce the required audio offset.


Edited by Rybags, Tue May 15, 2018 6:36 PM.


#11 x=usr(1536) OFFLINE  

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Posted Wed May 16, 2018 4:38 PM

Most older TVs do VHF and UHF - whether a computer does VHF 1 or UHF 36 doesn't matter much in this area though isn't VHF less common on UK sets?

 

Preface: my experience with this was with both Irish- and UK-market TVs.  I haven't lived in either country in 20 years, and while Irish-market items were generally the same as UK-market items, there were occasional minor differences.  I'm also getting older and my memory isn't the greatest, so take this for what it's worth icon_smile.gif

 

VHF was less common on Irish- and UK-market sets, but gradually became more common from the mid-'80s onwards.  However, I don't recall ever buying or seeing a device designed to connect to a TV (computer, VCR, or DVD player) via RF in that part of the world that didn't use UHF for its output.  IIRC, my 800, 800XL, various STs, and 2600jr. all output on UHF 36.

 

One exception I will add to that: VideoSenders.  These were essentially designed to take the RF output from a device and broadcast it to a TV within a couple of hundred foot radius; the couple of those that I had would let you change the broadcast frequency (not channel; spent a lot of time fiddling to get them on-channel) via a couple of screwdriver-adjustable pots.  At least one of them had a UHF / VHF switch and separate pot for the band you were setting it to transmit on.


Edited by x=usr(1536), Wed May 16, 2018 4:38 PM.


#12 Stephen OFFLINE  

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Posted Wed May 16, 2018 4:45 PM

That's crazy.  I only ever knew about devices outputting VHF 2 or 3 (some may have done 3 or 4).  This was in USA.



#13 Rybags OFFLINE  

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Posted Wed May 16, 2018 6:05 PM

Low-band VHF was/is common for blackbox devices - when FM radio became common the move started to get TV away from that band and in any case an FM station uses somewhat less bandwidth than a TV station and is less likely to cause interference.



#14 Mechanicjay OFFLINE  

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Posted Wed May 16, 2018 9:33 PM

This kinda ties into the whole idea that the 800 had these great user accessible slots for which there were only a criminally small number of  products ever released, but they weren't really an expansion bus like an Apple II or an S100 system.    But we have the totally forward thinking and probably too ahead of it's time SIO Bus -- things like the ART8000 show how far you could take that idea -- basically slaving the Atari to the ATR8000 while it ran CP/M.  This is basically what happens with an Apple II CP/M card as well.


Edited by Mechanicjay, Wed May 16, 2018 9:34 PM.


#15 tf_hh OFFLINE  

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Posted Wed May 16, 2018 11:14 PM

Pal only ever had Rev A os.  To best of my knowledge, no Pal 400/800 had a 6502B.

 

Would confirm that. I´ve repaired a lot of PAL 400/800 in the last years, but all of them had the CPU board with 6502C CPU onboard. I´ve also see some NTSC 800 with the 6502C CPU board and unpopulated parts for the PAL burst frequency generator, but never the other way.



#16 kheller2 OFFLINE  

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Posted Thu May 17, 2018 12:16 PM

:-) Kr0tki has made for us the OS B PAL ROM :-))) I used it on daily basis and it works like a charm. :-) So, thank you again for.

 

On the other hand, there is the source code for B, but up to now (2018) we have never seen a real OS B ROM.

 

If you have one, please let us know. Only 2 ROMs are still missing. Further, please check in here:

https://www.wudsn.co...ROMChecker.html

 

and for the 2 ROMs here:

https://atariwiki.or...?page=Rarity 10

 

 

The romchecker page needs updated with the latest info from here:             #64            



#17 luckybuck OFFLINE  

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Posted Thu May 17, 2018 12:37 PM

Thank you Karl, will forward the info to JAC!

 

:)






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