Date   : Mon, 12 Jul 1993 12:50:15 +1200
From   : David Andrew Sainty <David.Sainty@...>
Subject: Tube connections (was RE: colour Graphics)

From: "John K Nicoll" <jkn@...>
>Date: Sun, 11 Jul 1993 20:42:55 +0100 (BST)

>don't you guys have the Beeb circuit diagram? I'm amazed!

Definately wish I did!

>Anyway, here's something I dug out of the vault...

>40 way IDC connector.

>pins 1,3,...,27,29 - 0V
>pins 31,33,35,37,39 - 5V

>pin        2 - R/N         OP
>      4 - 2MHZ E   OP
>      6 - NIRQ     IP
>      8 - NTUBE    OP
>      10 - NRST    IP
>      12 - D0
>      14 - D1
>      ...
>      26 - D7
>      28 - A0
>      30 - A1
>      32 - A2
>      34 - A3
>      36 - A4
>      38 - A5
>      40 - A6
>
>hope this helps
>              john N

Certainly does! Pin 4 is the clock we need. With 7 address lines, that
should be enough to map some control registers to addresses not used by
2nd processors, so it needn't be the case that you could only have one or
the other plugged in. Strange though, I assume the NTUBE line indicates
an address space of 127 bytes is being addressed, within Sheila?

Oh, just noticed something else... NRST is down as an input here,
is that a typo? I'd expect it to be an output... (though plausably
could act as an input too)

Dave.