[BBC-Micro] Subject: Re: 'BASIC 512K'

Rick Murray rick at rs432.net
Wed Feb 17 00:00:37 GMT 2010


On 14/02/2010 12:37, jgh at mdfs.net wrote:

> Acorn were looking for something to step from 8-bit 6502s to a
 > suitable 32-bit CPU.

With lessons learned from the 6502, which meant a large number of 
existing processors would fail.


 > They approached Intel to see if they could license the 80x86 core,
 > but Intel were only interested in selling physical chips.

??!? Interrupt latency like that?!? IIRC the earlier x86 chips were 
horrible, not to mention the segmented memory system that, while it had 
a purpose, artificially crippled a lot of things that weren't prepared 
to jump through the hack-on EMS/XMS loops. An example being Borland's 
TurboC that choked on source files over 64K. I think TurboPascal does as 
well. TurboC++ fixed that, fair enough, but it shows that it was a 
problem. Oh, and memory models. What a pain in the ass. As a 
raised-on-RISC-OS coder I don't give a **** what memory model it wants, 
just give me an 80K array and don't flippin' argue or tell me a load of 
rubbish about _far pointers. It wasn't until the 80386 that it was 
capable of running a useful version of Windows, and it wasn't until the 
80486 that it could run said useful version of Windows properly.
God I'm glad Acorn didn't go the x86 route!


That said, they only contacted Intel? There's AMD as well. I think there 
used to be a third, but I forget. Not to mention the much nicer range of 
NEC Vxx cores which - given a market - might have made it to an x86 
version instead of 8088/8086?


That said (yikes, there's more?!?), I seem to recall around the time of 
the launch of the Archies that Watford carried adverts for an Aries 
workstation based around an 80386. Would Acorn have been able to be 
competitive in this market? At least the ARM gave Acorn the edge, not to 
mention wiping the floor with most similarly-clocked processors (8MHz 
68000 = 1MIPS, 8MHz ARM2 = 4.5MIPS). And as for the ARM instruction set 
in *use*... there's a lot to be said of putting together a software 
emulation of a BBC Micro that is perfectly usable on a machine that's 
only clocking four times faster than the original! Oh, the amount of 
time I wasted at school playing Chuckie Egg on the emulator...

And, while the software PC emulator was horrible, it stood as a proof of 
concept and actually, ironically, meant my A3000 was able to run stuff 
an actual 80286 crap-heap-of-a-clone couldn't run. It was tediously 
slow, it was ugly to look at, but it ran FoxPro. I mean like version 
zero before Microsoft got its grubby mitts on it. A business I worked 
for upgraded to a bunch of these PCs which would sort-of run some hacked 
version of DR-DOS, but stupid little things meant you'd often see the 
screen lose sync at which point you normally reached for the reset 
button. So "for a laugh" I booted the emulator, swapped floppies, loaded 
FoxPro... it worked. Well. Mostly. No reports, no printing, there was a 
lot of stuff I had to omit from the disc to get it to start, but it worked.

I don't recall when harddisc images were introduced, if that was in the 
software emulator or if it was !PC for the 386 podule. In any case, it 
made life loads easier than all that messing with floppies. It's just 
such a shame networking support was an expensive extra.


> The beauty of the Tube system was that it takes a very small bit of
> hardware and firmware to throw together a system that lets you
> experiment with a new CPU without having to build an entire system

Which could explain the variety of different sorts of Tube add-ons.


> Pure BASIC, with a snippet of assembler for background escape
> checking.

Sweet.


> I've started putting together an ARM version now the BASIC version
> has allowed me to flatten the bugs in the implementation.

:-)

My PVR runs an ARM926 core TMS320DM320] (as does my Creative Zen). 
Although it is probably 99% impossible (or too painful), my inner geek 
would love to get a bootable version of RISC OS... well... just because.

There might be some mileage in this thanks to Castle. The abstraction 
from the Acorn chipset means that it may be possible to rework the thing 
for other ARM cores (as is happening with the Beagle board). Sadly my 
PVR is made by some random Chinese firm that don't seem too interested 
in nerd support (even after I offered my time to improve the firmware). 
Oh the other hand, I am looking at a Neuros OSD with interest. Now the 
world is going HD, the older models are coming down in price. The OSD is 
about as open source as it's possible to get for one of these things. 
Could be some potential there to get a RISC OS kernel (if nothing else) 
running.


Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...
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