11 Nov
2006
11 Nov
'06
6:45 p.m.
On 11 Nov 2006 at 18:03, Chris M wrote:
It was said you needed an early bios to upgrade the
speed. So, if you had a model with the "early" bios,
you could toss in whichever crystal you wanted. I know
that up until some *bios* point anyway, the 5170 was
bump-uppable. But once they altered the bios (before
or after upgrading the 5170s speed?) you were stuck at
stock, whether it was 6 or 8 mhz?
The XT 286 did not use the same motherboard that the AT did--it would
have been physically impossible. As it was, the XT/286 was more
than a little cramped under the hood--a couple of the slots could
take only short cards. The other problem was that original "stock"
AT expansion cards were too tall to fit in the otherwsie XT-high
chassis. It was a bizarre beast, but a good performer for the money.
IIRC the memory used in the XT 286 was a bit odd also.
The original 5170's were 6MHz products. I'd heard that IBM
originally intended to ship 8 MHz units (certainly 8MHz 80286 CPUs
were available in 1986), but the idea of shipping a system that was
at least 5 times faster than the 5160 was nixed by marketing--I don't
know if the story's really true, but it would be typical of IBM of
the time.
I suspect this was behind the later incorporation of a speed check in
the later 6 MHz BIOSes--ant hat IBM shortly thereafter began shipping
8 MHz versions of the PC/AT.
FWIW, this intentional "dumbing down" to meeat a price point was an
old game. Others could verify this, but I believe that the only
difference between the CDC CYBER 72 and 73 was the addition of a
wait state or two. I'd heard that CE's could sometimes be bribed to
remove the offending jumper for customers.
When I was at Durango, we'd spec-ed our models for 7 and 14 MB Rodime
hard disks and set the pricing accordingly. Not too long thereafter,
Rodime discontinued the models and begin substituting (for no
addional cost) 10MB and 20MB drives. Marketing asked us to
artificially "clamp" the hard disk capacity in the OS so that
customers wouldn't get more than they paid for.
Only recentlly, I pulled out the CPU from an Toshiba Infinia 7230
(which used the Intel AN430TX mobo) and discovered that it was a 233
Mhz MMX unit, yet Toshiba had left the CPU clock at 200MHz on the
mobo because that's what the model was advertised as. I haven't
checked the 7201 that I have (ostensibly 160MHz, but it wouldn't
surprise me if a faster CPU were under the hood).
Cheers,
Chuck