6809 SBC

Jules Richardson jules.richardson99 at gmail.com
Mon Feb 1 10:19:05 CST 2010

Tony Duell wrote:
>> Hi!  When I designed the N8VEM 6809 host processor it is loosely based on an
>> article I read for the BBC computer called "Dragon in the tube".  I am not
> THe Dragon was, of course, the most common 6809-based computer in the UK.

Yes, there never was an official 6809 copro from Acorn - although there have 
been at least two homebrew ones (not including the linking of the Dragon).

  >> very familiar with the UK microcomputers but apparently 6809 "coprocessors"
>> were fairly common peripherals on their Z80 and 6502 designs.  I used a
> Were they? I've never heard of one.
> Acorn never (AFAIK) made a 6809 second processor for the BBC micro. The 
> original series of second processors (in 'chesse wedge' cases to fit 
> alongside the BBC micro) were the 65C02, Z80A, 32016 (originally 16032 
> :-)) and ARM 1. There was also a 32016 board with 4 times as much RAM 
> that was used in the Acorn Cambridge WOrkstation

No, there was no 'official' 6809 that I know of. My list of commercial ones is 
as follows (notional OSes in square brackets):

   Acorn 6502
   Acorn 65C02
   Acorn 65C102 (Master internal TUBE)
   Acorn Z80 [CP/M]
   Acorn ARM-1 AEK
   Acorn ARM-1 A500 (*not* the standalone machine) [Arthur, ARX, RISC OS]
   Acorn 32016 "small board" (256k/1M) [PANOS, poss. Xenix or ARX]
   Acorn 32016 "large board" (1M/4M) [PANOS, poss. Xenix or ARX]
   Acorn 32016 (Master internal TUBE) [PANOS, poss. Xenix or ARX]
   Acorn 80186 (Master internal TUBE) 512K [DOS+/GEM]
   Acorn 80186 (Master internal TUBE) 1M [DOS+/GEM]
   Acorn 80286 [DOS+/GEM likely]
   Torch Z80 "Communicator" [CP/N]
   Torch Z80 "Tosca" (with local serial comms) [CP/N]
   Torch 68000 "Neptune" [Uniplus, CP/N]
   Torch 68000 "Atlas" [Uniplus, CP/N]
   Torch 80188 "Graduate" [MSDOS]
   Cumana 68008 "Upgrade" [OS-9]
   PEDL Z80 [unknown]
   Crombie Anderson Associates 68000 "Casper" [FLEX]

And known "homebrews":

   Dragon/beeb hybrid 6809
   Graham Toal's 6809
   Jonathan Harston's PDP-11
   Acorn's VAX*
   Sprow's ARM7

* I have confirmation that it really did exist, but nobody seems to recall 
exact details. Near as I can tell, it ran a serial link between the BBC micro 
and the VAX though (rather than TUBE or 1MHz bus), so it's perhaps a loose 
definition of coprocessor...

> Is this article available on-line anywhere? Or do you have a reference to 
> it? It sounds as though it might be worth reading.

I have it, but I'm only finding scans of the second part on the server right 
now (from Electronics and Computing Monthly, September 1985). I think the 
first part of the article from the previous month's issue is buried in an 
email somewhere - if nobody else has it (& you don't happen to have those 
magazines anyway) I can go hunting for it.

The software (FLEX, customised for the BBC/Dragon hybrid) had to be sent away 
for, and I never could find a copy - if someone has it, I'd love a copy for 
the archive... (not least because hooking one of my Dragons to a beeb would be 
a fun project one day :-)



More information about the cctalk mailing list