On May 13, 22:34, Tony Duell wrote:
> Subject: Re: Acorn RiscPC 600 (OT - only 5 years old)
> You can trace links between the Atom and the Systems (Same bus, for
> example). And between the Atom and the BBC micro (Some of the
> non-standard parts of Atom BASIC turn up on the Beeb). The electron is
> obviously related to the Beeb. But I would claim that the Arch was also a
> BBC descendant. And thus the Electron is an offshoot of the main line of
> machines.
The Beeb video architecture is very similar to the Atom (but more modes,
more colours, more resolution), the disk system is almost identical, the
sideways ROM system is similar, Econet is the same, user port/VIAs are the
similar, etc. But they're all rolled together on the Beeb, and there's
lots more.
There were a few other "specials" like the Communicators built for Reuters,
looked like a Compact but had a different processor (the one that's based
on a 6502 but is 16-bit), and a built-in modem.
The Arc (not Arch, please :-)) was certainly built from the same philosophy
as the Beeb, and had some similarities in things such as screen modes, I/O
handling, OS entry points, etc. And like the Beeb, was well-documented.
> > micro and the ][ grew into the ][+ though I think the BBC micro
surpasses
> > the ][+ in terms of capability. The Master and //e both had to deal
with
>
> The Apple wins on hardware expandability (there are no expansion slots on
> any model of Beeb). The Beeb (IMHO) wins on a more powerful BASIC, better
> video system, more standard I/O ('User port, ADC, etc were all standard
> on the BBC micro, and properly documented in the user manual). Both are
> interesting machines.
The Beeb is also several times faster, largely due to the fact that I/O is
interrupt driven, and there's no polling overhead; also most I/O is
properly buffered and streamed. What's wrong with the 1MHz bus for
expansion? There were lots of devices that used that, including a
backplane system, and lots more that fitted (sometimes in ingenious, and
not always wonderful, ways) inside the case.
> No definitive list, alas. I can tell you the ones I remember :
>
> BBC A, BBC B, BBC B+, BBC Master. Master Compact. US models of some of
those
> (certainly there's a US version of the B).
>
> Some of those had 'professional' versions, or were available as PCB only
> for use in embedded systems.
The Master PCB was available separately as an OEM item. There was a series
of Acorn Business Machines, which were based on the B+ board, in a big case
which included colour monitor, B+ board, two 5.25" drive bays, second
processor, and had a separate keyboard and (for some models) a mouse.
There was one with a Z80, CP/M, floppies; one with 80286, floppies, MS-DOS
(or maybe it was DR-DOS), and one with a 32016, 4MB RAM, hard drive, and
one floppy. That was the only one that actually survived past the launch;
it became the Acorn Cambridge Workstation.
There was a also a pair of Springboard cards for PCs -- ISA cards with an
Arm on them. They differed only in the amount of memory, one was 1MB but I
can't remember if the other was bigger or smaller (4MB comes to mind, but I
might be wrong about that). They were basically a second processor for a
PC -- they used the PC's I/O -- meant for development work, and provided
with an editor, assembler, and a couple of compilers. They were sold by
the OEM division and not very many were made.
> Second processors for the BBC (not the internal ones for the master) :
> 65C02, Z80, 32016, ARM 1, 80286 (never released?)
>
> 80816 card for the Master (other master copros?)
4MHz 65C102 (Master Turbo), 4MHz Z80 (external only), 32016 (external only,
I think; Master Scientific), 80186. The Z80 wasn't a new design, it was
the same old Z80 as before. The others were new designs, and the Turbo and
80186 were available either as an internal PCB, or fitted in a box like the
original second processors.
There was also a short-lived Master ET. It was a Master 128 case and PCB
minus disk interface, minus some of the firmware, fewer standard I/O ports,
and limited expansion, but with the (otherwise optional) Econet networking
hardware fitted. A sort of diskless workstation.
> Peripherals in 'second processor cases' : Prestel modem, teletext
> adapter, GPIB interface, Econet bridge.
>
> Winchester (SASI) hard disk system. [Torch (IIRC) made a SCSI system as
> well.]
Acorn's used an Adaptec ACB400 which is definitely SCSI-1, not SASI. I
think Torch's was SASI -- and it never worked very well, I seem to recall.
Its protocol was sufficiently different to the Acorn standards that lots
of stuff wouldn't work with it.
> > - Was the source to the MOS ever released or reverse-engineered?
>
> Never released, and I've never seen a reverse-engineered version :-(
Yes they were. I have two separate copies of the source/commentary for the
MOS. They were issued at Acorn training courses, which were run for
dealers and developers. There were a range of courses, and I went to one
of the MOS courses run by Paul Bond (who was the major designer of the
MOS). It was a fascinating course.
> > It's very well documented but there are some undocumented
features.
> > (One example came up in the discussion of the Torch Z-80 card.
> > It involved interrupts at power-on time, I think.) How about
> > the source or disassembly for BASIC?
Software interrupts. The Torch Z-80 does it badly wrongly, which is why it
screws up several other add-ons. At power up, various service calls are
offered to all the ROMs in turn, and the Torch Z80 uses one of them for an
unintended purpose. it also claims one it shouldn't, instead of passing
control back correctly.
> > - The Proton _is_ the same as the BBC micro, right? Some Web sites
> > seem to disagree on this!
>
> Yes.
No! The Proton was a design for the successor to the Atom, and that was
the design initially shown to the BBC when they started to canvas for
material for what became the Microcomputer Project and the "Making The Most
of The Micro" TV series. The BBC asked for, and got, several major
changes, and the BBC Micro was quite a bit bigger and more complex than the
Proton would have been. The proton was more like the Atom than the Beeb.
> > As for finding a machine, I thought there was a place in London selling
them
> > new but I haven't checked yet.
There was a batch of machines that turned up from the U.S. at one point, so
beware that they are a different spec (video timing, mostly, but also a
different ROM) and I think there was a batch came back from Germany.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
Received on Thu May 13 1999 - 20:04:43 BST