New Research Machines finds

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Fri Dec 19 18:11:53 2003

>
> On Thu, 2003-12-18 at 21:06, Tony Duell wrote:
> > I have a metal-cased 48Z somewhere (in fact I've never seen a
> > plastic-cased version).
>
> I'll do you a swap... I have seven of the plastic-cased ones ;-)

Round here, metal cases tend to last longer than plastic ones (less
damage when some heavy PSU topples over onto them...)

>
> I would like to get one of the metal ones sometime just to complete the
> collection a little. I've never even seen one to be honest, just the
> plastic variety. Even Bletchley don't have one, just a mammoth pile of
> 380Z's.

Before this thread, I didn't ever realise there was a plastic 480Z. I
assumed all were metal, like the 380Zs (those _were_ all metal, I trust).

And I would never regard Bletchley as having anything close to a
definitive computer collection!

>
> > I also have a 380Z with 56K, high-res graphics
> > and 2 intenral 5.25" drives.
>
> I'm not sure what this one has yet. It came with a mono monitor, but a
> quick glance the other day shows some circuitry behind the BNC
> connectors for the colour output too - but maybe they all had that
> anyway. I'm going to have a closer look at it in a moment.

No, the 4-BNC-panel is an _option_ for the hi-res card. If you have that
you have the hi-res option too.

You'll have 2 boards at one end linked together by a ribbon cable fixed
to one of them. Those are the processor, base 32K RAM and 40col
text/block graphics video. The PSU and keyboard connect to those -- and
technically it's possible to have a 380Z with just those 2 cards.

Youi probalby also have the 50 way bus ribbon cable coming from one of
those cards, across the machine, to a terminator card (full of resistors)
at the other end. Othe cards will be connected to this bus cable.

You may have (amongst others) :
32K extra memory (of which I think only 24K cna be used). This is
actually a CPU board missing many of the chips and with different address
decoder PROMs.

Hi-Res graphics. This will also connect to the mono video connector (The
SO239) on the back and will have a cable connecting it to the mono video
output on the CPU card (and another ribbon cable carrying timing
signals?) The mono video output then carries the mix of the CPU-board
text video and the hi-res video. The RF (Belling-Lee coax) connector just
carries the text video. There's a header on the Hi-Res board that carries
the output from the colour lookup table RAM (and, I think, the text
video). There's an external resistive ladder DAC board that mounts on the
back and gives RGB + composite sync on 4 BNCs, or you can flip an
internal switch/jumper to get sync-on-green

Disk controller. This is obvious, it's cabled to the floppy drives. It
contains a 1771 chip (FM only), and IIRC, a real serial port. There are 2
versions of this card, for 8" and 5.25" drives

User I/O. Not to be confused with the user port on the CPU card which is
present on all machines. The User card contains several Z80 PIOs and a
Z80 CTC, toghether with a wire-wrap area.

I am told there's also a GPIB card, aanlogue I/O etc, but I've never seen
them.

> However, a) it's a web document, b) it's in PDF format and c) it's 30MB
> so I'm not sure what your chances are of being able to get it and read

I have no intention of downloading 30Mbytes using a 14K4 modem....

-tony
Received on Fri Dec 19 2003 - 18:11:53 GMT