On Fri, 30 Aug 2013, Ed Vance wrote to mark lewis:

 EV> I then remarked, does XT stand for eXpired Technology?, he never
 EV> thought of that before, but he would tell that to all of his
 EV> friends who were still running XTs.     

hahaha... XT was eXtended Technology IIRC... it was a step up from the
plain original PC... the addition of the HD and the necessary BIOS
modification to boot from it were one of the main extensions... also there
were more slots (8) on the XT but they were spaced closer together than in
the PC... the XT also allowed for more memory on the motherboard (256k)
than the PC (64k)... the PC was limited to a maximum of 256k memory whereas
the XT could handle up to 1M but only 640k of that was usable by the
user... the BIOS, adapter ROM/RAM and video RAM filled the inaccessible
384k of that 1M space...

 EV> That AT of his must had been a 286, I guess.

yes, ATs were introduced with 6mhz 80286 CPUs in them... they also had the
16bit ISA bus as compared to the PC and XT 8bit bus... this also worked
well with the 286's 16bit design architecture... the AT also came with a
20M HD (compared to the XT's 10M or 20M in later models)... later the
brought out the 8mhz 80286 with a 30M HD... the AT's 80286 CPU was
specifically designed for multitasking but the huge majority of them were
sold and used as single user machines... they were "simply"
faster DOS boxes to most folks...

 EV> B4 I got a 486 in 1994, I learned from reading messages on BBSes,
 EV> and later on, on a ITT XT at work by typing in the Example Programs
 EV> from the Manuals that came with the XT.

i started off on a TRS-80 and their BASIC... then later i was downloading
BASIC programs from a system up in michigan when i was in oklohoma... i
already knew some BASIC so i set about modifying those downloaded programs
to add color since i was working on a PCjr with color monitor... later a
friend turned me onto PASCAL and ASM and i never looked back... BASIC's
PEEKs and POKEs never made sense to me but i knew and understood what they
were doing... i was just never able to figure out where folks got those
lists of codes from and what they actually meant... it wasn't until i got
into ASM that it struck me as to the OPs codes they were using...

 EV> That ITT with DOS 2.11 was a real good PC, in fact when it was
 EV> replaced by a Zenith 286 I thought the XT worked better than the
 EV> 286 did.  But what do I know???????????

the 286 was plagued by a few problems but those were HD based... once the
HDs were replaced, they didn't have any more problems...

FWIW: the 32bit 80386 was brought out by COMPAQ in 1986 IIRC... this was
the first time that the (de facto) PC Compatible standard was updated by a
company other than IBM...

)\/(ark