Talking of the 380Z...

[Jules Richardson]

On Sun, 2005-07-03 at 19:17 +0100, Tony Duell wrote:
> > We've got several 380Z's (well, two or three) that have no drives in
> > them - I expect those are tape-only systems. Unfortunately I've never
> 
> Thay may have been used with external floppy units. The only way to be 
> sure is to see what PCBs are inside.

It's on my to-do list... it's just been there for about a year now :-)

> > important to do! I know we've got one of the 8" drive setups too which
> > are rather rare, plus we've got one 380Z-FD machine which should have
> > the "full disk" controller in it (on-board RAM, ROM, its own Z80 cpu
> > etc.).
> 
> I was readign the 380Z service manual on vt100.net this morning. It was 
> the first time I'd come across this board, it looks rather fun.
> 
> 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 -
the simple one (still with an SIO-4 on board) with an FD1771 IC on
board, and the one that I thought was the 'full disk' controller with
the on-board CPU etc.

Far as I know, the former board is FM only and can put about 70KB on a
disk, whilst the latter one can do MFM and gets about 240KB on a disk.

I'll have to have a look inside our FD machine and see what disk board
it has... 

> FWIW, the normal, non-intellegent disk controller has a SIO-4 on the same 
> PCB, but it's nothing to do with the disk controller function. Obviously 
> on that board you can go from serial port to disk without using the rest 
> of the machine.

Yep. :-)

> I believe the SIO-4 board (also SIO-5, SIO-6) was just a disk controller 
> board with the serial chips fitted and the disk controller chips not 
> fitted. 

Ahhh, that's an SIO-4C according to the disk system info file - the
board for the SIO-4 always has the disk controller circuitry with it
according to that doc. RML didn't half make things confusing.

> 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
like stuffing PAL chips with different colour codings into all their
stuff, and I'm not aware that the equations are documented anywhere.
(Your mention of the RAM board made me think of that, as the PAL is
different for a RAM board versus the equivalent on the CPU board)

> > firmware should allow communication direct between the disks and the
> > serial port - I believe it's the same board as used for the 480Z shared
> > disk system)
> 
> 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. 

> > What we don't have is keyboards. In some cases that's not such a big
> > deal as with the later serial boards they could run from a terminal
> > rather than system keyboard & display.
> 
> The keyboard interface spec is in the Information File and service 
> manual. The latter also contains a scheamtic of  _a_ keyboard, but from 
> what I rmemeber the one I have is very different.

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. 

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
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
what device to use as output, though...

> In the xase of the 380Z, what I want to do is to try to load a real RML 
> tape, sort out the replay phase using that, then sort out the recording 
> phase so I can load my own recordings.

I'll double check regarding tapes. I've got about half of Bletchley's
RML software here, and one of the other guys has the rest - so it may be
that he has one or more tapes...

cheers

Jules