Floppy disk controller card

[TALKINGWITHPYE]

Thanks all, tried all the obvious cable configurations and the bios settings are correct so I am stumped. The pc is very old so possibly a mother board fault. It still programs the Philips fm1100 radios so it is not completely useless but it would be good to get the floppy drive going.

Dave

[Dave Moll]

Originally Posted by TALKINGWITHPYE

Hi all, when looking for the CMOS battery on the motherboard I was surprised to find that there wasn't one.

If your computer maintains its time-of-day clock while switched off, there must be a (working) backup battery of some sort, either rechargable or replacable.

[ortek_service]

Originally Posted by cmjones01

There are lots of real time clock modules out there which have a battery built in. They're often made by Dallas semiconductor. Common in some test equipment is the DS1287, but I don't it has a real time clock, just battery-backed RAM.

The batteries fail, of course, which requires replacing the whole module with a new one (if available) or a substitute.

Chris

The DS1287 is actually a (Motorola MC146818 compatible?) RTC, as well as the usual spare bytes of 'CMOS' RAM as it became known and used by BIOS etc. And unfortunately have a primary lithium battery so may only last 5-10yrs before requiring complete replacement (luckily usually socketed).
Although not too many PC's used these (mainly old Amstrad ones), and they were quite expensive / probably now obsolete (and old stock won't be too good)
It is often possible to cut the battery off the top, and fit your own coin cell etc. - I have seen pictures online of this being done - to keep the original going.

[SiriusHardware]

Actually, modern equivalents are still being made, see the DS1287+ here, from Farnell.

https://uk.farnell.com/maxim-integra...p24/dp/2518671

The datasheet on that page says they are a drop in replacement for the original DS1287. Not cheap, but probably cheaper than sourcing a whole replacement computer.

[SiriusHardware]

Apologies if we have already asked, but have you tried several more discs?

If memory serves me correctly you would get the same message 'General failure' if you just tried to read a faulty disc. If you have any other surplus discs try formatting one, and if that succeeds try copying a file to the disc and reading it back.

[G6ONEDave]

It could also be a faulty ribbon cable, they sometimes failed at the wire to connector joint. If I remember correctly the first floppy socket was B drive and the end one was A drive, some ribbons even had sockets for MFM drives. Well worth trying a known good ribbon cable and also check if the drive is cable or link detect for it's drive letter.
Dave

[yesnaby]

My daughter's suggestion for any obscure fault is 'hit it with a hammer' ...

[Slothie]

Originally Posted by G6ONEDave

It could also be a faulty ribbon cable, they sometimes failed at the wire to connector joint. If I remember correctly the first floppy socket was B drive and the end one was A drive, some ribbons even had sockets for MFM drives. Well worth trying a known good ribbon cable and also check if the drive is cable or link detect for it's drive letter.
Dave

Given that he's tested the drive in another computer I suppose he could test the cable in the other computer too. It's lookng a lot like controller failure, which give the age could be down to capacitor aging or some physical damage to the board.

[SiriusHardware]

The FD controller is on a multi I/O card, not on the motherboard. TWP has already been kindly provided with an absolutely identical Multi I/O card which has not fixed the problem.

[Slothie]

Originally Posted by SiriusHardware

The FD controller is on a multi I/O card, not on the motherboard. TWP has already been kindly provided with an absolutely identical Multi I/O card which has not fixed the problem.

Ah, I must read more carefully. I thought that board was still in transit.

[TonyDuell]

I'm wondering about problems with the DMA channel or IRQ line used by the floppy contoller. Unfortunately the appropriate circuitry is likely to be part of a large ASIC on the motherboard and not easy to debug or repair.

[Slothie]

Originally Posted by TonyDuell

I'm wondering about problems with the DMA channel or IRQ line used by the floppy contoller. Unfortunately the appropriate circuitry is likely to be part of a large ASIC on the motherboard and not easy to debug or repair.

Well it must be something like that because the drive & cable have been tested and the same fault with a different card means its the MB unless the replacement card has the same fault. Try the controller in another PC? Although the other PC may not have the ISA slot required.