MIKE ROSS wrote in a message to Roy J. Tellason:

 MR> "Roy J. Tellason" wrote to "MIKE ROSS" (18 Dec
02  20:06:09)  ---
 MR> on the topic of "THOSE OLD EXPENSIVE [2/2]"

 >RJT>  Anyhow,  TeleVideo took a different

 MR> Oh, ya, just recalled a Televideo board as the only I've ever seen
 MR> an 80186 used in. IIRC it also used 32 x 64256-12 drams for 4M???.

 RJT> There were a few 186 (and maybe even 188) machines out there,  but
 RJT> what happened was that early on it became *imperative* that the
 RJT> 8088-based stuff be "pc-compatible".  There were a few
machines that
 RJT> weren't,  and they disappeared in short order.
 RJT> Unfortunately,  IBM in the design of that machine chose to use some
 RJT> interrupts that intel had called "reserved",  which came into play
 RJT> with the 186/188 chips,  that's why those were never used all that
 RJT> much.

 RJT> The boards that did sell were for people who wanted a more powerful
 RJT> machine, and didn't care too much about pc compatibility,  not a very
 RJT> significant portion of the total market.

 MR> I just looked through my memory trays to check the part numbers of
 MR> the drams and they were TMS4256-12 (TI). However, they are 16 pin
 MR> not 18. So these are probably equivalent to 41256 drams not the
 MR> 64256. The board then had 1Meg not 4M as I mistakenly thought.

 MR> The 186 instruction set wasn't too different from the 8086. There
 MR> were only a couple significant instructions such as PUSHA and POPA
 MR> which would save and restore all the flags and a few to handle
 MR> multiple frames, multiplication in memory, and indexed string I/O.
 MR> The resulting machine would still have been quite compatible even
 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).

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

The big step up with the 186/188 was integrating a lot of hardware that
would've been in separate parts on the earlier chips.  I'm not at all sure
about the software differences,  and mention what I did above because
that's what I heard about why they never really amounted to much in the
clone market.

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

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