6502.org

Or you can define a line that is one pixel in length. Either way you do it, it's the same issue: a lot of ANSI-style mumbo-jumbo is required. You can effectively forget the idea of drawing a full-screen bitmap image. You might not live long enough to see the results.

It's 6 bytes per plotted point in Acorn VDU code. Just saying.

And you could define a custom 8x8 pixel character for single use. Eleven bytes to plot a block of 64 pixels, assuming the cursor's already in the right place.

That may be, but I notice that when I select the internal setup menu the screen gets painted at leisurely pace, certainly no faster than the real VT-100 painted its screen. While it's not a problem for me, I really was expecting a quicker response.

I get it. You don't like that "minicomputer rubbish." I'm not fan of the ANSI/VT-100 command set as well. As I earlier opined, it looks like a classic "designed by committee" mess (which it is—ANSI is the one who conjured it).

If you don't care about any kind of standards you are free to implement anything you want. However, it is more useful in the general scheme of things to pick a well-known standard and stick with it. That way your creation will (theoretically) work with others' creations that also adhere to that well-known standard.

In my case, I implemented the WYSE command set in my POC units, which meant I could connect any WYSE-compatible terminal, or any PC running terminal software that knows the WYSE command set, to the computer and have a working user interface. When I get ready to actually connect the VT-100 gadget to POC V1.2, I will implement the ANSI command set, for which I already have a definitions file.

I have a design and some code for a PIC32 based VT-100/220 terminal that was part of a three chip SWTPC 6800 emulator project that uses a similar chip in the same family.

VGA output. Just text no graphics and PS/2 keyboard support.

Did you ever do anything with it? Also, does it have a cursor? Lack of a cursor seems all-to-common in quite a few of the terminal-on-a-microcontroller thingies I've looked at.

I was intending to have one along with support for the blinking attribute. My PIC24 based composite video version had both.

[oops, ironically posted in the wrong thread. BDD and chromatix seem to be chipping away at each other's project ideas in two different places. And I'm trying to chip away at the chipping away - I wish everyone would just let things be. If you don't like an idea, leave it to stand for itself. If others like it, let them enjoy their findings.]

I eventually got around to developing my own variant of this board.

The design criteria was to have something that could attach to the back of an LCD (or other) monitor and take it's power from the monitor. I initially started out with a PS/2 keyboard, but they are getting harder to find. My initial attempts also just had TTL serial levels. You can read about the process here (warning - non-6502 site!): https://altairclone.com/forum/viewtopic.php?f=5&t=333

This final version has a RS232 driver chip, will accept a USB keyboard and color and baud rate are DIP switch selectable. The overall area of this is just about the same as the original.

That looks beautiful, Bill. Nice layout...

Thanks!

Just to update this post a little. I too wanted to add some terminal capabilities to my various retro projects. I went to Geoff's page for this and he graciously included updates to his design in the comments at the end of the page. I went to all the sites he mentioned and ended up with a few alternatives. The board produced by Gary Kaufman looked better to my use and I ordered this and built one which works fine. I also downloaded the updated firmware from David Hansel which could make use of USB etc and while there noted his Versaterm using the Raspi pico and ordered some of those boards as well. They work very well, no composite video out, but has the option of HDMI (actually DVI through HDMI jack). I also looked at the offering by Peter Hizalev but since his boards were not available at the time, I took his firmware made 2 alterations to the Kaufman board put in the 20 Mhz (for the 8MHz)Crystal and used the PIC32MX270 chip rather than the MX250 and the display quality is improved over that using Geoff's design, although there is no composite out available. Finally I also tried Grant Searle's Terminal using AVR(Pic)Mega328 for PS2 and Composite video and that also works well if you are limited to Composite video. Its not a complete VT100 implementation but works well enough for me. After all that I tend to use the Versaterm since there is a 3D printed case design available to make the thing a little neater on my bench.
Many options if you want to set your project free from your PC and terminal emulator.

Peter Hizalev sells a replacement MCU for the original Geoff Graham design that requires a PCB bodge-wire patch in order to work in Geoff’s original circuit.  The replacement is clocked at a higher frequency and produces a better-looking set of glyphs.  Accordingly, I purchased the replacement MCU before I had looked at the nature of the patch.

When I inquired about the patch, Hizalev referred me to a page on Hackaday, which has an image of a piece of the original circuit with unspecified changes.  The image is in color, and being partially color-blind, I cannot read it (what I can see of the image looks to have been generated from Kicad, which I don’t use).  I tried to convert the image to monochrome, but some parts were too washed out.  When I requested an illustration of the patch in monochrome, Hizalev was uncooperative and repeatedly referred me to the Hackaday page.  Accordingly, I left a negative review on his Tindie site and am recommending he not be used as a source for anything.