Date   : Sun, 22 Jul 2007 15:14:30 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: modern BBC remake

>Message-ID: <469DC88F.6050204@...>
 
I think the way I'd go is:
 
Pinouts on the PCB to plug an Econet card into
PCB holes to mount all extension connectors
  PCB holes for 9-DIN serial connector
  PCB holes for 9-DIN mouse connector on the user port
4 ROM sockets for 16K/32K ROMs
IDE connector
PC keyboard connector
If duplicating a Master, PCB pinouts to plug an intenal CoPro into
 
A FPGA containing everything else:
  a 65(whatever)02 CPU
  128K RAM
  Control logic
  Devices that "look like" the standard BBC devices to the CPU, ie
  accessing FE00/01 accesses something that responds just like a
  6845 would respond, accessing FE08/9 accesses something that
  responds just like a 6850 would respond, etc.
  Half a dozen gates to give an IDE interface  
 
Plus: border control register at FE02
Access to an analogue RGB palette
 
Try and get the PCB a similar size as an external second processor
PCB with mounting holes in the PCB to match the CoPro, so a copro
board can be clamped to the NewBeeb PCB.
 
If it can't squeeze onto a single PCB, two PCBs mounted one on
top of the other would half the footprint.
 
I'm picturing something about 12cm by 20cm which would fit inside a
project box, about the size of two ZX Spectrums one on top of another:
 
      rom slots
   -----------------------------------
     |                             |
     | other bits                  |
   -----------------------------------
 
Molex connectors for an Econet card and internal CoPro.
 
I would want space around the edge of the PCB for the following
external connectors:
 
5-DIN     9-D    6-DIN    BNC     RF  PC-KBD  +5v/+12v
Econet   Serial   RGB    Video                  Power
 
34-IDC    25-D     9-D Mouse/    34-IDC   40-IDC   40-IDE
Floppy   Printer   20-IDC User    1MHz     Tube     IDE
 
Maybe some sort of connector to allow it to be plugged into
another host computer. I like Adrian Lee's Z80-on-a-Podule card.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
Youth has now fled. Their best years have been passed in the service
of the party. They are ageing and their ideals have also passed,
dispersed by the contrarities of daily struggles.