"Roy J. Tellason" wrote to "MIKE ROSS" (19 Dec 02  20:06:17)
 --- on the topic of "THOSE OLD EXPENSIVE [2/2]"

 MR> though the hardware was different. For example a lot of programs
 MR> ran well on machines like the Tandy 1000's even though they used an
 MR> 8086. The only real hangup on those was the video which was better
 MR> than the pc's but couldn't be directly written to in the same way
 MR> (i.e. bad for games).

 RJT> That was the thing,  if it wasn't _that_ compatible then it wasn't a
 RJT> clone.  I worked for a bit at a local store that was selling Sanyo
 RJT> machines,  back around the end of 1984,  beginning of 1985.  The acid
 RJT> test was to try and run something that had a reputation for being
 RJT> fussy,  like flight simulator.  Which they did,  only they neglected
 RJT> to mention that they were running a version that was specific to that
 RJT> machine...

That's it, that early Tandy 1000 also had to run machine specific games
which naturually used a different way to access the video. A few games
would even run under both by offering a Tandy graphics option in the
startup menu. Hmmm, reminds me the Tandy 1000 also had a 3 or 4 voice
synthesizer chip for sound which at the time was light years ahead of
the pc's speaker port bit banging horror. That why the Adlib sound card
was invented for the PC and later the Soundblaster improved on that.


 MR> The 186 instruction set wasn't too different from the 8086.

 RJT> The big step up with the 186/188 was integrating a lot of hardware
 RJT> that would've been in separate parts on the earlier chips.  I'm not at
 RJT> all sure about the software differences,  and

You know, I don't think the software was the problem. I think the hex on
the 186 was that it fixed the FFF0: segment wrap bug of the 8086 which
had become the standard method to access expanded memory. Wouldn't it be
the kicker if the 286 came out with the bug purposely put back in!
Actually all cpu's since... imagine that! IIRC there was something else
that struck me as odd about the 286 in that purportedly if one pin was
grounded it operated as an 8086. I vaguely remember seeing a 40 pin 286
in an XT but being used as an 8088.


 RJT> Even the newest and fastest machines out there these days still look,
 RJT> in large part,  like the earliest,  in terms of how the software sees
 RJT> it.

Oh, stop it now! You can't run flight simulator 1.0 on a new machine!!!
In fact much software became useless when the 386 came out mostly due to
timing issues. For example things like the Adlib music card were highly
dependant on tight timing delays and these were the first to stop
working right under the early software.

 Mike
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