New finds: enough Torch stuff to sink a battleship

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue Jul 1 18:38:00 2003

> Hi Tony,
>
> > No idea... What (if any) chips are missing from your Stickleback, other
> > than the Ethernet chipset?
>
> I haven't had time to open the case today, but a glance the other day didn't
> show anything big around the VME bus interface; it looked to all be 16 pin
> chips and the like. I got an email from the guy today saying the following:

The VME interface doesn't have any big chips. It's TTL buffers and a few
small PALs...

>
> [ Not a theory - I know that one is the original prototype. The VME interface
> [ didn't work on that PCB issue. I've an idea that it's got a prototype EPROM
> [ in it that doesn't require a key disk. IIRC on that box of Eproms I gave you
> [ there is a "Simon" eprom - that's a debug boot EPROM that doesn't use the
> [ key disk system
>
> Interesting. I noticed that Simon ROM and wondered what it did :-)

Hmmm.. i have Simon too, but I thought it still needed the key disk. It
lets you boot from arbitrary files on the hard disk, though which is what
makes it useful. But UniPlus+ still seems to need a key disk to boot...

> > The monitor I am thinking of is almost entirely a Sony chassis, with a
> > little Torch PCB at the input carrying the 8 pin DIN socket and
> > connectors to the monitor video board (flat in the bottom) and the speaker.
>
> that's what the 10" ones are like inside. I pulled the case the other day to

I am not sure if mine is the 10" or 13"...

Looking from the back there's the video PCB flat in the bottom. On the
left is the PSU PCB with the chopper control PCB plugged into it. On the
right is the scan PCB with the raster correction PCB plugged into it.
There are a couple of other PCBs for the controls, and the Hstat block
screwed to the metalwork...

> see what the connections were but didn't need to go any further than the small
> PCB carrying the connector so I don't know what's lurking deeper within (yet)
>
> > I think that 'NC' pin is for the interrupt input from the touch switch.
>
> there's some bodged circuitry (cut tracks, extra capacitor and a desoldered
> resistor etc.) in the corner of the board near the video circuitry. Maybe
> that's something to do with the power-mechanism bypass (or might well be
> something else entirely)

Can't help you. The power control is handled via the service processor
(6803 IIRC)...

> > One question? Is there a ROM or EPROM on this board connected to the 1MHz
> > bus side of things? The reason I ask is that there's some feature of the
> > BBC micro where you can get it to execute code from a ROM in one of the
> > 1MHz bus address spaces after a reset, if you hold one of the interrupt
> > lines low or something. I wonder if that's where it gets the hard disk
> > drivers from...
>
> No, not on the SASI board. There's a Torch ROM on the Xebec controller, but the

It's not going to try to boot from that...

-tony
Received on Tue Jul 01 2003 - 18:38:00 BST