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J3 on revision D needs to be configured, with out the baud divider connected there is no tx/rx clock to the 6850

I will confirm that these are the correct connections when I get home, I can't remember what problems it caused without the connections . But when I brought the board up I got video fixed first then memory and finally the lifted pin to boot. I think I would have remembered if it was backwards, but s...

Hi Bill, I believe in my information sheet I sent with the board showing the 4 missing traces that need to be made the one resistor to put in the other hole , I believe I made a note to leave that pin out of the socket, when I made the mod my trace was still connected on that pin, it does not boot o...

As long as it does not have the twist

The 610 and d13 with out modifications are set for dual single sided drives the side select line is connected to ds1 and disk select is ds0 so you get 2 single sided drives after the mods you should be able to still use single sided drives because there is no side select on those drives in theory if...

@Bill

your memory issues could be the problem writing to the disk do you have the same buffers chips in the 600 and 610 ie 8t28 not 8t26's

Make sure you have good ground between everything, I was using a different supply to power my drives and had all kinds of problems till I grounded everything together

I have a little progress with the 510 I made a 48 buss interface to connect to the 610 and a modified BillO memory board , I disabled the 610 ram and have been using 56k ram with no glitches at all (ready for cp/m),also a modified AT power supply with +5 +12 -9 -12 now time for a case (just a rough ...

here is another view

ERR #9 seems to be a common problem when trying to make a disk using boot code, as mike suggested different media has solved it for me, but also switching between starting the boot code at 2217 then 2a51 and back , once the formatting catches all seems to go well, and once you get the disk made all ...