Acorn RiscPC 600 (OT - only 5 years old)

On May 13, 22:34, Tony Duell wrote: 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. surpasses with 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. those 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. 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. 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. 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. features. 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. 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. them 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