5 Feb
2024
5 Feb
'24
11:16 a.m.
-----Original Message-----
From: Paul Flo Williams via cctalk <cctalk(a)classiccmp.org>
Sent: 05 February 2024 16:24
To: cctalk(a)classiccmp.org
Cc: Paul Flo Williams <paul(a)frixxon.co.uk>
Subject: [cctalk] Re: vt220 firmware source?
On Sun, 04 Feb 2024 16:26:57 -0700
Richard via cctalk <cctalk(a)classiccmp.org> wrote:
Hello Paul,
Your annotated VT100 listing was invaluable in helping me to fix my own VT100 (still not
working though, but on the video output side). Would be interested in how you did it, I
get the impression from your message that you used an emulator to observe the behaviour?
Thank you so much!
Rob
In article
<A5E5BE0A-362D-4C0E-A3EC-CA503039F3FA(a)fritzm.org> you
write:
Well, in case it helps, I'll explicitly disclaim any intention of disassembling the
VT220 :-)
After the VT100, I did make a start on the VT102/131 combination but it
seemed too samey to hold my interest. I'm about to dive in to commenting the
disassembly listings, but
figured I'd ping here to see if anybody might have done this already
in case I wouldn't have to start from scratch?
Give IDA Pro or Ghidra a crack at it to help you make sense of the raw
disassembly.
I made pretty good progress on VT100 ROMs before Paul Williams put up
a completely reverse engineered commented listing.
More than 20 years ago, I started on the VT320, as my personal favourite, but
I didn't understand how to tackle emulation at the time, the 8051 emulator I
wrote had flaws, and I spent a long time on getting the emulated video timing
correct enough to even pass self test! If only the VT320 had had a technical
reference as comprehensive as that published for the VT100. I will return to it
at some point, probably using some else's 8051 core, as Peter Sichel (last head
of DEC's terminals group) bet me that I wouldn't be able to do it.
At the moment, I'm tackling another full commentary, but it may well have an
even smaller audience than that for the VT100; I'm 83% through gutting the
arcade game Star Force. I've even fixed two æsthetic bugs in the game, 40
years too late for anyone to care. At least this is Z80 assembler, and tinkering
with that has always made me *very* happy.
Paul.