26 Nov
2002
26 Nov
'02
5:10 a.m.
I was musing about the state of VT100s and other dumb terminals and
had a few ideas zing by...
Many of DECs dumb terminals are Z80 based with custom video hardware,
yes? Has anyone ever decompiled or reverse-engineered the code to
analyze the core code? I know that Kermit has a more-than-adequate
terminal implementation in it, but Kermit is more suited for a machine
with an OS and a C run-time library, not embedded devices.
Has anyone on the list ever worked with complete BIOS replacement
on a commodity Intel motherboard? ISTR Tony Duell or someone here
was contemplating doing some task by removing the ROMs from a 5150
board and replacing them in their entirety. With a decent terminal
emulator package, that would be one way to implement a DIY dumb
terminal.
Where I'm going with this is embeddability and portability. Obviously,
for use such as we had in the old days, a real Wyse or real VT100 or
VT220 is the way to go... simple and easy... plug it in, turn it on.
I have used my Palm Pilot as a portable terminal for reconfiguring
Cisco routers (VT100 app and a travel cable and the appropriate
RS-232 dongles). My boss at the time flipped when he saw me do it
(everybody else dragged a laptop into the server room). There are
just times when I'd like a laptop-sized-or-smaller ANSI terminal.
I can forego double-high/double-wide chars, inverse video and the
like for simplicity's sake (hardly ever used them in an app except
at the South Pole), but it should be complex enough to run a
screen editor (vi or emacs) and/or basic curses apps (Rogue/Larn/NetHack
and the like).
One place I thought BIOS replacement might be handy was in a sub-486
laptop.... just pull it out, plug it in and *voila*, it's a dumb
terminal weighing a few lbs. Yes, it's possible to drop an OS on
a floppy and add Kermit (I've already done that with a dual-720K-
floppy Zenith 8088 portabie). I'm thinking of a dedicated "instant-
on" experience.
I also have some "Net Stations" with a 5"x5" 486 motherboard stuffed
under a PC keyboard (with 4 30-pin SIMM sockets, IDE, serial, video,
and NE2000 network built-in). They don't run off batteries, but
neither do they have an intergral screen.
I've also tried to think of ways to adapt a Palm Pilot with a permanent
keyboard, but I'm not sure there's a way to do it with only one serial
port (terminals typically have at least two, even if one is dedicated
to servicing the keyboard and somewhat "invisible" to normal operation.
The final angle I've worked on is to recycle the main board in a
VT220 (being somewhat physically small), but I don't have schematics
and I don't know what signals go over the ribbon cable to the PSU/
Analog board under the CRT.
So has anyone else wrestled with how to cobble up a portable VT-100?
Anyone get any further?
-ethan
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