Talking of the 380Z...
ard at p850ug1.demon.co.uk
Sun Jul 3 22:13:59 CDT 2005
> > I thought the 'full disk' controller was the 8" one (which was
> > essentially the same as the normal 380Z controller), and that the one
> > with the on-board Z80 was the Intellegent Disk Controller. But I could
> > well be wrong.
> Hmm... I've only seen schematics for two different disk controllers -
There are only 2 boards. The 8" controller is the same as the
non-intellegent 5.25" one. There are notes on the schematic for the link
settings for the FDS (== 8") and MDS (== 5.25") versions.
> Far as I know, the former board is FM only and can put about 70KB on a
The 1771 is certainly FM (single density) only.
> disk, whilst the latter one can do MFM and gets about 240KB on a disk.
I've not seriously looked at those schematics yet...
> > Much as the RAM expansion board is the same PCB as the CPU board,
> > but you leave off the CPU and buffers, etc.
> Actually, info on the various PAL chips would be handy; RML didn't half
THere were no PALs in the original set of boards (CPU, VDU, hi-res, disk,
etc). WHat there were -- and were to excess -- were small bipolar PROMs.
Those were often colour-coded.
I will have to check, but I may well have dumps of some of those somewhere.
> > That's what the service manual implied. I have a 480Z (one of the older
> > metal-cased ones), but no disk unit for it.
> Aha, I've got a 480Z disk unit here - never tried it as I need to sit
> down and figure out the cable wiring which puts a bit of extra time on
> the task.
It would be useful to know the protocol that the 480Z uses to talk to the
disk unit. From what I remember, though,, it uses the serial chips in
synchronous mode, which means finding another machine that could act as a
disk server would not be totally trivial.
> It does seem that there were a few different keyboards, but I'm not sure
> how they differed internally. Far as I know, they all talked the same
> protocol to the CPU though.
They did. 7 bit ASCII code and a strobe line. That much is documented in
the Infroation File.
> I think hacking a PC keyboard to work with a 380Z would spoil the
> machine though :-) I'd rather use a period terminal and drive things
COnsidering my Infromation File is dated November 1981, a PC keyboard
_is_ period :-)
> that way. Hitting a key on the terminal at system start should be enough
> to wake things up and tell the 380Z to use the terminal as input rather
> than the usual keyboard. Can't remember if there's a way of telling it
Are you sure about that? I've never seen it documented anywhere.
> what device to use as output, though...
> I'll double check regarding tapes. I've got about half of Bletchley's
Thanks. But absoutely no hurry -- this is very much a 'to do sometime'
project, and it's been on the list for many years!
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