Re: BBC B+ Disk Drive issue

paul wrote:
Hi Steve.

I have problems with dirty drive heads which can be cleaned with cotton buds and isoproyl alcohol; although I would expect an error and not to experience it on two drives in a row so I think this is unlikely.

I assume the DFS or ADFS rom is recognised with an appropriate DFS or ADFS header on the boot screen. If not check the rom chip is seated, or remove the rom without bending the pins, check all the pins are clean, and blow out any dust from the socket and reseat. Sometimes I use the edge of a ruler to bend the all the pins on the chip out a little on each side, before reseating the chip to improve the contact against the socket pins.

Check you have correct filing sytem for the disks you are using, games are generaly on DFS systems, and will not read if you are using ADFS filing system; but I would expect an error message if this was the case so I think this is unlikely.

Check the loose socketed chips, go through all the socketed chips on the motherboard and apply a little pressure to seat them a bit firmer.

Check the disk cable, if you used the same cable for both drives I would try another cable. If one of the connections in the cable is broken, that can cause this behaviour. If you can't find an bbc cable, you can use an old pc cable with the edge connectors so long as you don't use the connectors with a twist in the cable between them.

Check the disk drive connector on the bbc board, just check the connector pins are clean, not loose, bent, or missing.

Check the 1770 disk drive controller, this chip should be socketed, but the chips can get loose. remove the chip without bending the pins, check all the pins are clean, and blow out any dust from the socket and reseat. It is possible the 1770 controller chip could be faulty and would need to try a replacement.

If all that fails, would need to investigate deeper in to the dfs circuitry.

The B+ has a 1770 disk controller, and it is easy to hook up a basic 3.5 pc drive, it should connect with a standard pc cable so long as you use the connectors without a twist between them. You will need to source a double density (not high density) floppy disk with an Acorn DFS or ADFS image on it. If you have a double density disk, you can use omniflop software to write a DFS or ADFS image to it on a PC.

I hope that helps.

Regards,
Paul.


Thanks for all the info Paul. I actually have a brand new BBC 3.25 floppy drive too that I haven't used yet - I'll try out the DFS with that too. I'll also try reseating all the ICs and give the board a good cleanout.

The DFS definitely is active and comes up on the bootup screen. The 1770 definitely isn't socketed on the B+ also, it's soldered in firm which makes replacement a pain, and makes me think I'd get on better with a vanilla B board.

Steve
.

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