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Anyone recognize this 810 mod?


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#1 tep392 OFFLINE  

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Posted Mon Dec 28, 2009 10:39 PM

I bought a 400 and 810 drive on ebay recently and was pleasantly surprised to find a few undisclosed modifications. The 400 had an aftermarket ram expansion and the 810 drive has some kind of modified rom. I don't know what the modification does though so thought I would post a picture in hopes that someone might know what it is. The rom chip sitting off to the side has the numbers for a factory 810 rom. The side board has an eprom and a few extra wires soldered to it.

Any guess about what this is?

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#2 jaybird3rd ONLINE  

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Posted Mon Dec 28, 2009 10:53 PM

Interesting. Another member once asked about these boards in an earlier thread, and it seems that the extra board at the top (part number CO17227) is an Atari daughterboard containing the floppy controller chip and an external data separator. Apparently the early versions of the floppy chip (the 1771 you see on the daughterboard) had inadequate data separators built in, so this board was added to early 810 drives to improve their reliability. Perhaps the EPROM and jumper wires were installed as part of this upgrade.

#3 Larry OFFLINE  

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Posted Tue Dec 29, 2009 7:21 AM

The so-called "Grass Valley" 810 upgrade?

Original 810's were unreliable to the point that people were hacking the 810's adding data separator circuits from other floppy drives. A guy in our user group had one of these hybrids, and IIRC it had a Percom or TRS data separator hacked in. When I got my first 810 in 1982, fortunately it had the upgrade. It's been a long time, but those boards look like what was in my original 810.

-Larry

Interesting. Another member once asked about these boards in an earlier thread, and it seems that the extra board at the top (part number CO17227) is an Atari daughterboard containing the floppy controller chip and an external data separator. Apparently the early versions of the floppy chip (the 1771 you see on the daughterboard) had inadequate data separators built in, so this board was added to early 810 drives to improve their reliability. Perhaps the EPROM and jumper wires were installed as part of this upgrade.



#4 tep392 OFFLINE  

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Posted Sun Jan 31, 2010 10:13 AM

The so-called "Grass Valley" 810 upgrade?

Original 810's were unreliable to the point that people were hacking the 810's adding data separator circuits from other floppy drives. A guy in our user group had one of these hybrids, and IIRC it had a Percom or TRS data separator hacked in. When I got my first 810 in 1982, fortunately it had the upgrade. It's been a long time, but those boards look like what was in my original 810.

-Larry

Interesting. Another member once asked about these boards in an earlier thread, and it seems that the extra board at the top (part number CO17227) is an Atari daughterboard containing the floppy controller chip and an external data separator. Apparently the early versions of the floppy chip (the 1771 you see on the daughterboard) had inadequate data separators built in, so this board was added to early 810 drives to improve their reliability. Perhaps the EPROM and jumper wires were installed as part of this upgrade.


I think I have it figured out now. I found some info on the daughterboard and C version rom. They both went into production in late 1981. My drive was made in early 82 so it would have had these from the factory. The EPROM responds to the Archiver s/w and will write bad sectors while copying so I believe it is an Archiver chip. It might be a bootleg copy though. The 1966 written on the chip is the open code.

Thanks for the help everyone! It's been fun and educational researching this drive.

Perry

#5 tregare OFFLINE  

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Posted Sun Jan 31, 2010 2:21 PM

Interesting. Another member once asked about these boards in an earlier thread, and it seems that the extra board at the top (part number CO17227) is an Atari daughterboard containing the floppy controller chip and an external data separator. Apparently the early versions of the floppy chip (the 1771 you see on the daughterboard) had inadequate data separators built in, so this board was added to early 810 drives to improve their reliability. Perhaps the EPROM and jumper wires were installed as part of this upgrade.



even the later 1771 chips had marginal data seperation :(

#6 sup8pdct OFFLINE  

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Posted Mon Feb 1, 2010 6:26 AM

I bought a 400 and 810 drive on ebay recently and was pleasantly surprised to find a few undisclosed modifications. The 400 had an aftermarket ram expansion and the 810 drive has some kind of modified rom. I don't know what the modification does though so thought I would post a picture in hopes that someone might know what it is. The rom chip sitting off to the side has the numbers for a factory 810 rom. The side board has an eprom and a few extra wires soldered to it.

Any guess about what this is?


please ignore

Edited by sup8pdct, Mon Feb 1, 2010 6:27 AM.





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