Does anyone has firmware source code for any terminal in the VT100
series?

On Sunday, May 16, 2021 at 1:12:09 PM UTC-7, lars...@nocrew.org wrote:
> Does anyone has firmware source code for any terminal in the VT100
> series?

Do you have ROMs to disassemble?

Or isn't that good enough?

On Sunday, May 16, 2021 at 1:12:09 PM UTC-7, lars...@nocrew.org wrote:
> Does anyone has firmware source code for any terminal in the VT100
> series?

Disassembled with some comments is here:

https://www.pcjs.org/machines/dec/vt100/rom/VT100.txt

On Sunday, May 16, 2021 at 1:12:09 PM UTC-7, lars...@nocrew.org wrote:
> Does anyone has firmware source code for any terminal in the VT100
> series?

Service manual is here:

http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf

gah4 wrote:
>> Does anyone has firmware source code for any terminal in the VT100
>> series?
>
> Disassembled with some comments is here:
> https://www.pcjs.org/machines/dec/vt100/rom/VT100.txt

Thanks, I do have this. Some more comments would be nice, and
especially original symbols and comments.

I'm totally clueless as to what was inside a VT100.
How much of its functions was controlled by firmware?
What was the processor?
Did folks/site hack it to be custom?

I remember DEC pushing a model with some sort of PDP-11 chip and an 8" floppy behind the blank panel next to the screen. I don't think I ever saw one in use outside of DEC marketing material. I'm guessing this was 79 or so, well before the Rainbow and Pro 350, which came years later

On Wednesday, May 26, 2021 at 1:20:56 PM UTC-7, fishtoprecords wrote:
> I'm totally clueless as to what was inside a VT100.
> How much of its functions was controlled by firmware?
> What was the processor?
> Did folks/site hack it to be custom?
>
> I remember DEC pushing a model with some sort of PDP-11 chip and an 8" floppy behind the blank panel next to the screen. I don't think I ever saw one in use outside of DEC marketing material. I'm guessing this was 79 or so, well before the Rainbow and Pro 350, which came years later

As above, the service manual is here:

http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf

It seems to be 8080 based, as were many things at about that time.

Usual use for firmware is to read characters from the keyboard and send them out the serial
port and/or write them to the screen. Read them from the serial port and write them to
the screen.

Using firmware allows for all the control functions, even CR/LF, to be performed, much
easier than in hard logic. It also allows for programmable functions, changing modes,
and all that.
I suspect that not a lot of hacking was done, though possibly changing the character
generator for unusual use, maybe even APL. Maybe not until after the warranty was up.

According to gah4 <gah4@u.washington.edu>:
>I suspect that not a lot of hacking was done, though possibly changing the character
>generator for unusual use, maybe even APL. Maybe not until after the warranty was up.

I used a fair number of VT100s and don't ever recall anyone hacking the firmware.

--
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

fishtoprecords wrote:
> I'm totally clueless as to what was inside a VT100. How much of its
> functions was controlled by firmware? What was the processor?

Glad you asked! I have now written most of a simulator for the V100
hardware. (Not breaking new ground; there's one in MAME, and another in
JavaScript.) The CPU is a plain Intel 8080(A? not sure). It
orchestrates most of the hardware. The custom video chips use DMA
(temporarily suspending the 8080) to get characters from RAM and has its
own character generator ROM. The LK40 keyboard has discrete logic to
scan the matrix on command from the 8080.

See chapter 4 here for details:
http://bitsavers.org/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf

> Did folks/site hack it to be custom?

In a way yes, including DEC and 3rd parties.

The original VT100 came with an expansion port. In the basic
configuration it did not have enough RAM to display the full 24 lines in
132 column mode, just 14. And only one attribute bit per character,
which could be toggled between reverse video and underline.

The AVO - Advanced Video Option - board would add 1K of RAM and also
make it 12 bits wide. This made 132x24 possible and four more
attributes per character. The VT101 and VT102 are cost reduced
unexpanable models without/with AVO built in. And new firmware.

There's the VT18X board which added a complete Z80 computer with
floppies, capable of running CP/M.

Selanar Corporation made a graphics add-on called Selanar Graphics 100
Plus. http://www.bitsavers.org/pdf/selanar/Graphics_100_Plus_Mar1982.pdf

On Thursday, May 27, 2021 at 10:57:16 PM UTC-7, lars...@nocrew.org wrote:

(snip)
> Glad you asked! I have now written most of a simulator for the V100
> hardware. (Not breaking new ground; there's one in MAME, and another in
> JavaScript.) The CPU is a plain Intel 8080(A? not sure). It
> orchestrates most of the hardware. The custom video chips use DMA
> (temporarily suspending the 8080) to get characters from RAM and has its
> own character generator ROM. The LK40 keyboard has discrete logic to
> scan the matrix on command from the 8080.

If I was in the mood to do it, and so far I am not, I would do it in an FPGA.

There is already an 8080A in HDL, so then you need the display logic.
Usually emulate the keyboard through an interface to a PC keyboard.

gah4 wrote:
> If I was in the mood to do it, and so far I am not, I would do it in
> an FPGA.

That wouldn't be very hard, especially if the 8080 is already done.
There's also an ER1400 EAROM to store the SET-UP parameters. The
keyboard is responsible for the beep sound and key click in a peculiar
way.

On Friday, May 28, 2021 at 2:06:33 AM UTC-7, lars...@nocrew.org wrote:
> gah4 wrote:
> > If I was in the mood to do it, and so far I am not, I would do it in
> > an FPGA.

> That wouldn't be very hard, especially if the 8080 is already done.
> There's also an ER1400 EAROM to store the SET-UP parameters. The
> keyboard is responsible for the beep sound and key click in a peculiar
> way.

There is another 8080 based terminal I had a thought of doing as an
FPGA emulation, but didn't get to (yet) described here:

https://www.retrotechnology.com/dri/SLAC_8080.html

referencing the PDF here:

http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-r-199.pdf

This one does smooth scrolling with a large character buffer using
a metal wheel on the side. Or, it can go to graphics mode and use
all the memory for bitmap Tektronix 4013 emulation. Also, it has
the ability to use either the built-in character generator, or one
in RAM, loadable by the user.

I had forgotten about the beep and click. I do remember that the VT100
keyboard has a 1/4 inch thee conductor phone plug (like old headphones)
to plug in with.

Otherwise, it would be nice to have a little FPGA board, with the right
hardware to emulate things like terminals and early microprocessor
based computers. Not so much extra stuff that they like to add on.

gah4 wrote:
> There is another 8080 based terminal I had a thought of doing as an
> FPGA emulation, but didn't get to (yet)

Probably a good choice. As much as the VT100 is a loved classic, my
rose-tinted view of it is changing as I get to know it better. As many
people here probably know well, it's not a speed demon when it comes to
processing input.

> This one does smooth scrolling with a large character buffer using a
> metal wheel on the side. Or, it can go to graphics mode and use all
> the memory for bitmap Tektronix 4013 emulation. Also, it has the
> ability to use either the built-in character generator, or one in RAM,
> loadable by the user.

Sounds like a great machine!

> Otherwise, it would be nice to have a little FPGA board, with the
> right hardware to emulate things like terminals and early
> microprocessor based computers. Not so much extra stuff that they
> like to add on.

I think there are a few with just the basics: an FPGA, some DRAM, VGA,
PS/2 keyboard and mouse, maybe Ethernet. I think there's a CADR Lispm
board that fits this description but really, it could also be used for
many similar class computers and terminals.