Date   : Thu, 07 Jul 2005 21:33:48 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Compressed Model B

> Message-ID: <42CD45C1.7020009@...>
 
Richard Gellman <splodge@...> wrote:
> >Rather than use a BBC why not try a Mini Beeb
> >http://homepage.ntlworld.com/rpsprowson/bbc/minib.htm
> >
> And two, that board doesn't look to be too BBC Micro compatible. I've
 
It's fully BBC compatible if you use legal system calls. What you
mean is that it doesn't have the same hardware as a BBC.
 
> not read in-depth, but since it runs its own OS (as opposed to OS1.2)
> the phrase "Repton won't run on this" springs instantly to mind. Nice
> little device though.
 
Repton will run on it. As MiniBeeb doesn't have a 6845-driven
bitmap display you won't see anything, and as it doesn't have an
internal data-bus matrix keyboard you won't ke able to control
what you can't see.
 
Do you really mean that you want a system that the OS 1.20 ROM
will drive, or a system that is drivable through the legal system
calls.
 
> Re: The advice on conglomerating parts: I'll be economising where
> possible, but I want to stick pretty close to the original circuit. Some
> parts will be eliminated, but the basics need to be present, 6502, 6845,
> 6522 VIA-A, VIDPROC, RAM, SAA5050, sound chip, WD1770 + support
> componets (ideally).
 
There's a IPFA project that puts an entire ZX Spectrum onto one
IFPA.  Essentially, you could put together something that looks
like, eg, a 6845+SAA5050+2x6512s from the point of view of the
CPU, and the CPU will not know any different.
 
John Kortink <kortink@...> wrote:
> In any way, you'd better first re-engineer some parts
> of the circuitry, i.e. lump together sideways ROMs,
 
Please have some sideways ROM sockets available for plugging
physical ROMs into. I'd have, maybe, eight sideways banks
accessible as PCB sockets and eight sideways banks within bulk
onboard non-volitile memory.
 
> memory, glue logic. Into single, modern parts (flash
> ROM, static RAM, CPLD respectively). Will save a /lot/
 
I remember in the eighties there was a BBC in a box the size of a
large box of matches - about the size of two 3.5" hard drives. I
can't remember what it was called, and never physically saw one,
but always wanted one, and met somebody at Univeristy who had
taught microprossesor programming with them.
 

-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for Windows and Internationalisation
  See http://mdfs.net/Software/BBCBasic/Windows/ProgTips