Odd FDC problem (Compupro)
julesrichardsonuk at yahoo.co.uk
Tue Jul 19 06:30:11 CDT 2005
On Mon, 2005-07-18 at 21:52 -0400, Dave Dunfield wrote:
> Hi Guys,
> I've got a Compupro 8086 based S-100 system which has been on the "to do list" for
> a while, and yesterday I finally got the CPU reference manual which was the missing
> piece ...
> I've "almost" got it working, according to the docs, it should flash the drive select
> light about once/second with no disk in the drive, as it tries to read --- this it
I probably won't be at Bletchley until this weekend, but we got a
Compupro 8/16 a few weeks ago with a *lot* of documentation. I could
have a flick through that assuming nobody's taken it home with them...
> The odd thing is that if you put a disk (any disk) in the drive, it immediately stops
> selecting it - it's as if getting the index pulses from the disk prevents the FDC from
> proceeding ...
If you're seeing different behaviour occasionally, then this can't be
it, but I remember our machine did something very similar to this if the
drive cabling was back to front; the drive LED would pulse but then as
soon as a disk was put in it'd do nothing.
> Sometimes, usually after taking a board out to check something, it will actually try
> and boot from the disk - If you put Disk-2 of the Compupro CP/M 86 distribution in the
> drive, you can hear it boot, it seeks a bit and obviously reads a track or two - after
> the first seek, you can see the RTS+DTR lights come on on all three serial ports, which
> suggests that it has come up enough to init the serial ports ... but I do not get any
> output on any of the three ports.
Are the disks known to be good? It does sound like a faulty connection
though - does moving the boards around to different slots make any
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