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From: thad@cup.portal.com (Thad P Floryan)
Newsgroups: comp.sys.amiga
Subject: Re: JR-Comm VT100 emulation
Message-ID: <37439@cup.portal.com>
Date: 1 Jan 91 00:04:04 GMT
References: <600@caslon.cs.arizona.edu> <37397@cup.portal.com>
  <647@faatcrl.UUCP>
Organization: The Portal System (TM)
Lines: 35

First, I'm happy to hear that Dave P. Schaumann solved his difficulty with
JR-Comm V1.01, and am pleasantly surprised to hear that Jack Radigan enhanced
the "base" D.J.James' COMM program so well.

As far as "VT100" compatibilty goes, if a program doesn't 100% pass the Per
Lindberg "vttest" VT100 validation suite, then a program is NOT compatible.

"VT100" compatibilty has become a de facto "standard" to which many terminals
and emulators aspire due to DEC's successful marketing in this regards and the
presence of many terminal clone manufacturers.  Even AT&T saw the need to make
SVR3.* curses specifically VT100 compatible in terms of the line-drawing char
set for boxes.

At my office we have REAL DEC VT100, VT220 and VT240 terminals, and also
Datamedia DT80 and Falco TS1 clones.  And we have IBM-PCs, Macs and Amigas.
Nothing on the Macs or IBM-PCs will properly emulate a VT100; NOTHING.
Handshake on the Amiga does, and so apparently does A-Talk-III and now,
presumably, JR-Comm.  But I'll reserve judgment on those last two until I
*see* them do 80 and 132 columns along with double wide and double-wide/-high
characters and pass every part of the Per Lindberg validation suite.

You may scoff at the need for FULL VT100 (and not just ANSI) compatibility
until you encounter the tens of thousands of programs which need the VT100
capabilities, and NOT just on DEC computers.

What baffles me is why it seems to be so difficult for "emulator" writers to
get it right, especially using an MC680x0-family CPU.  A real DEC VT100 has a
dinky 8080A CPU, and the Datamedia DT80 uses an 8085 with only a few 4Kx8
EPROMs; the Datamedia DT80 is actually a better VT100 than DEC's own VT100!
About 8 years ago (1983) I wrote a 100%-compatible VT100-emulator in assembler
which fit in an 8Kx8 EPROM for an MC6803 CPU; just requires a straightforward
fsm (finite-state-machine; state transition matrix; decision table; whatever)
to parse the ESCape codes, branch off to subroutines, and do the right thing.

Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]