Date   : Wed, 08 Feb 2006 21:26:34 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: 1 MHz Bus backplane

"Mike" <profpep@...> wrote:
> I've seen a few references to a 1 MHz bus backplane system.
> 
> Does anybody have any details of the configuration. I have details of a
 
Could be from "Interfacing the BBC Microcomputer", Colin Opie,
McGraw-Hill, 1983.
 
The author devloped a motherboard for interfacing to the BBC using
2x30way Euro-board connectors. Rather expensive, I would have
thought, for hobbyist development. What to play with interfacing?
First, spend loads of money and time on learning how to make and
on building PCBs.
 
The motherboard connected into the Analogue, User and 1MHz ports.
The Euro-connectors provided the following signals:
 
        0v   A1   B1   0v
        0v   A2   B2   0v
Analog GND   A3   B3   AC0  Analogue port lines
       AC1   A4   B4   AC2
       AC3   A5   B5   PB0
      Aref   A6   B6   PB1
                 --------------------------------
       LPS   A7   B7   UD7
       UD6   A8   B8   UD5  User port lines
       UD4   A9   B9   UD3
       UD2   A10  B10  UD1
       UD0   A11  B11  CB2
                 --------------------------------
       CB1   A12  B12  A7
        A6   A13  B13  A5
        A4   A14  B14  A3   1MHz port lines
        A2   A15  B15  A1   Address and Data buffered
        A0   A16  B16  0v
        D7   A17  B17  D6
        D5   A18  B18  D4
        D3   A19  B19  D2
        D1   A20  B20  D0
       AIN   A21  B21  nRST
      nPFD   A22  B22  nPFC
      nIRQ   A23  B23  nNMI
      1MHz   A24  B24  R/nW
         -   A25  B25  -
         -   A26  B26  -
      +12v   A27  B27  +12v
      +12v   A28  B28  +12v
       +5v   A29  B29  +5v
       +5v   A30  B30  +5v
 +5v unreg   A31  B31  +5v unreg
 +5v unreg   A32  B32  +5v unreg
 
The publishers also produced "Interfacing for the Spectrum",
with the same eye-bending cover-art and with a similar expensive
motherboard system. (I've been trying to track this book down.)
It inspired me to create my own cheap 'n' cheerful version with
cast-off parts from the Medical Physical Department that my Dad
worked in using single-line connectors that didn't need PCBs,
see http://mdfs.net/Info/Comp/Spectrum/Backplane I also designed
an adaptor that let me plug my Spectrum backplane into the
Beeb's 1MHz connector!
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
NOBODY expects the MACRO ARGUMENT INQUISITION!  Our chief weapon is
unexpected addressing modes... unexpected addressing modes and local
branches out of range.  Our two weapons are unexpected addressing modes and
local branches out of range and quoted argument lists.  Our *three* weapons
are unexpected addressing modes, local branches out of range, quoted
argument lists, and an almost fanatical devotion to the pope.  *Amongst* our
weapons are such elements as unexpected addressing modes, local branches out
of range... I'll come in again.