Yet another VT-100 emulator
dave06a at dunfield.com
Sat Dec 22 04:27:54 CST 2007
> > Although there are cheap CF cards today, it would be a hit if it could
> > be ROMable and put in place of BIOS chip :o)
> If you can still find them, ancient XT motherboards ought to be just right for
> this type of service. Just get an old video board (will it work with a CGA
> board?) and a serial I/O card and plug in the "extra" bios chips for the
> emulator. Of course, several options could be added:
> 1) Support for a character based printer (both serial and parallel)
> 2) Some sort of scrolling (got to use that 640k of memory somehow!)
> 3) Color support (if you got a CGA card, use it!).
> 4) Provisions for 40 column mode (so you can use the RS-170 output to a TV
> 5) Add a network card for a telnet client (probably a bother since there are
> so many network cards)
> The best part is that when you turn the machine on, you get instant terminal.
> None of this silly operating system stuff.
This might not be as difficult as you might think. The terminal is written
using my own Micro-C compiler, and I do have an embedded version for the 8086
family that makes code not requiring an operating system...
I'm not sure about targeting an XT - I like the features you can get with
VGA (full VT-100 graphics font, proper attributes) and the enhanced AT
keyboard. AT's and 386's are a dime a dozen, and 16 bit slots are easier to
get VGA working in - extra ROM sockets are harder to find however. You also
get CMOS RAM which could be used to store terminal parameters if you do
replace the BIOS.
Replacing the BIOS would be a bit tricky, as it would be realy nice to
be able to use the VGA BIOS for compatibility with the most cards. I
don't know what would be involved in enabling the VGA BIOS without the
standard BIOS - normally they hook together.
I'd have to rip out the scripting language, file transfers and other
features which assume files...
But is all this worth it? .... The program is tiny (about 20k .COM)
and easily fits on a boot floppy with DOS, it's config file (or
multiples if you want to save multiple configs) and a few scripts if
you like to automate things --- So you wouldn't need a hard drive,
CD etc. just a single floppy. and you can have it today.
Telnet might be a bit trickier, but one might be able to use wattcp
to provide the ip services. Use of packet drivers would provide
compatibility with MANY older network cards (and is another case
where booting from a DOS floppy would make sense) - how much
interest would there be in a stand-alone telnet VT-100 ?
dave06a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
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