Date   : Tue, 15 Jun 1993 10:13:00 +1200
From   : David Andrew Sainty <David.Sainty@...>
Subject: Other Beebs

   From: Jeremy Prior <jez@...>
   Date: Mon, 14 Jun 93 9:54:40 BST

   All,
       Could anyone explain the major differences between the various BBC
   models - BBC B, BBC B+ and BBC Master machines.  I am familiar with (and
   own) several Model B's but don't know anything about the rest.

The main differences were the disc drive interfaces and the memory
management.

Both the B+ and Master had disc drive interface as standard and used
a double density capable device.

The B+ had shadow ram, and a 12k block of sideways ram.

The master has far more memory, 128k ram. That's 32k + 20k shadow ram +
64k sideways ram + 4k in sideways ram area + 8k rom workspace.

My personal favourite enhancement is the 8k ram for rom workspace.
I actually designed and built something for the model B to do
precisely that job, I was going to use it with ADFS and my newly
aquired Hard drive, but then I got a master, so the project was
prematurely halted.... Pity really! If anyone wants to carry the job on
I can probably find some of my old notes, or just explain what I did...

The other enhancement between the B+ and Master is that both shadow and
main memory ram banks can be displayed, or stored in main memory. The output
of the OS VDU drivers can be redirected to either too, the theory being
that you can do nice switching between teh banks for animation purposes.
But not much has been done with that....

Processor runs the same speed. Graphics the same (I always thought they
should have bunged in some minor shades capability in the Master).

Facility for internal co-processor (And internal modem, I've never heard
of one though!). What else... Oh, a CMOS 6502, that's quite a big
improvement! People have praised Acorn for not using a Rockwell 6502
in the master on grounds of rarety (Rockwell is slightly enhanced again).
That's a pity, could have squeezed a bit more power out there....

Memory is dynamic. Oh, almost forgot! Real time clock and battery backed
setup! Cartridge ports... don't like them so much, I'd prefer internal
rom sockets. Numeric keypad....

Hmmm, there's more differences than I thought! OS is much improved, and
has neat extras like *EDIT (which is definately where it's at! Except
pity it can't edit large files off disc....).