Connecting a Vintage Monochrome Monitor to a Modern PC

Question

I am considering taking my nostalgia for the eighties to the next level and getting hold of a green monochrome monitor. In particular, the nine inch monitor of the Apple IIc, but maybe something else depending on price and availability. If you put 'monochrome' into Ebay there are a number of options.

It would be good to run a terminal of my modern Debian on it, either a second monitor with the terminal in it and modern stuff on the main monitor or booting into recovery mode and running only terminal programs and commands.

This might be harder on a notebook which is limited to USB and HDMI ports, but easier on a desktop where you can perhaps the appropriate 'graphics' card, or maybe better called 'anti-graphics' card if it exists.

Does anyone know hard or time consuming it would be to achieve this? On the surface it sounds like it might be easy, since these monochrome monitors and Unix were developed around the same time, but there are possibly some details of the electronics and signal transfer which could turn it into a nasty electronics project. If there were a simple adaptor from the notebook to the monochrome monitor, I may do it, but then if you have to design and build your own circuit and circuit board would probably leave it out for now. Then there is the software side of it, such a thing is probably not going to be 'plug and play', you're going to have to tell Debian what kind of monitor it is.

Answer 1

The Apple IIc monitor (A2M4043) mentioned in the question takes a composite video signal. Some older laptops and graphics cards output composite or S-Video either directly or through a breakout cable. Otherwise, an external graphics adapter that interfaces to the PC via USB and outputs VGA is about $10-15. Once you're working in the analog domain, you have a few options, such as a pre-built adapter that converts VGA to composite or S-Video for about $25-30.

Or you can take the "dumb terminal" approach. Gary Kaufman's ASCII Video Terminal (an update to Geoff Graham's original design) connects to a host PC through RS-232, outputs text to VGA and Composite, and takes a PS/2 or USB keyboard for sending commands back to the host computer.

If your monitor were VGA, I would recommend Peter Hizalev's version (full kit here for $52) with a much better font.

Personally, I'm interested in the old TTL (Hercules/MDA) monitors such as the Zenith 12 inch ZVM-122 (amber) or ZVM-123 (green) CRT, but I don't know of a good way to drive these from a modern computer. Maybe modify Peter Hizalev's code for MDA timings, find an appropriate font, and cobble up an HD-15 to DE-9 adapter?

Answer 2

Does anyone know hard or time consuming it would be to achieve this?

Assuming you have a modern PC with VGA out, or you can put in a graphics card with VGA out, it's not hard at all, if you know a bit about how this works.

You need to look up the horizontal and vertical sync frequencies that your monitor operates with (use the documentation, or google for online documentation, or if you know it was connected to e.g. an Apple II, then use those). Often the old monitors only worked at exactly these frequencies, and using others (in particular higher ones) could be dangerous for the monitor and even destroy some of the earlier monitors. So be careful.

Then you need to program the graphics card to use those frequences. On Linux, with X, this is done with a modeline; there are plenty of tutorials and tools that help you making one. On Windows, it's more tricky, and I'd have to google that, but I'd assume it can still be done editing some configuration files, or the registry.

On the hardware side, you'll probably need a VGA converter to whatever input (e.g. coax) your monitor uses. Simplest way would be to just use one color channel (e.g. the green one). You can make those yourself with a bit of soldering skills.

Answer 3

VGA was a huge and very bold rejection of NTSC!

TLDR of this whole history section: VGA and NTSC have nothing to do with each other. VGA was a blank-sheet design that smashed NTSC limitations with extreme prejudice - and planned to never, ever, ever go back.

Apple IIc monitors, like most monitors of that age, use the NTSC composite video standard in all respects that are not incompatible with their purpose. For instance monochrome displays do not use the color modulation obviously. S-video displays deliver luma and chroma separately. RGB delivers R G and B as three separate monochrome channels. Other than that, they are NTSC through and through.

These were tentative tiptoes away from traditional NTSC; they stayed with the standard in all other respects - frame rate, scan line rate, timing and screen dimensions. This frustratingly limited screen resolution, right up until VGA finally smashed the "glass ceiling": it threw away NTSC altogether and started with a blank-sheet new design. The word was "we will no longer support using your TV as a display device; get a dedicated PC monitor".

And THAT required the market to shift from "basically everyone using TVs as their display" in 1977 to "almost everyone using a dedicated PC monitor" - and remember at the time, monochrome monitors were $200-300 and color monitors were $700. Even in the mid-1980s, the need to drive a TV had strong sway - can you imagine the PCjr shipping with no ability to connect it to a TV? Impossible!

The only company ever to get away with smashing the NTSC monolith was IBM, with their niche Monochrome Display Adapter (MGA) in 1981 (~350 scan lines per field instead of the usual 200).

So again it was IBM to introduce original VGA (640x480 non-interlaced per field), with their meant-to-be-revolutionary Personal System/2 (PS/2) line. IBM was correct that nobody in the business world cared about TV support and would not object if asked to pay $700 for a dedicated-to-purpose color monitor. The goal of VGA was to entirely free computer displays from the albatross of NTSC limitations. No NTSC support was even imagined; the goal was to leave NTSC in the dust.

*But mind you, 1987 was also when the Amiga was starting to "find its feet" in the marketplace. Heck, Amiga's Video Toaster launched in 1991 and wound up becoming the king of midsize TV production for the whole decade - a lot of local TV markets used the Video Toaster for graphics and fonting of news, commercial production - Amigas even did the CGI on Babylon-5.

But the market message was clear: All-in, or all-out of NTSC. No more "stuck in the middle", no more "NTSC albatross dragging down PC resolutions".

It isn't resistors

As such, there are only 2 ways to get from a VGA output to an NTSC-family display:

• Use a frame buffer
• Have the video card be versatile enough that you can change its parameters to actually output NTSC timing signals, even though they will be RGB of course. From that point it's simply a matter of mixing the sync and luminance signals correctly, and yeah, that you can do with analog circuitry... but only if the video card is able to do all the heavy lifting because its designers were extra clever and provisioned the ability to do that weird old thing.

Really, you're better off starting from scratch

The right way to solve this problem, really, is to have a USB or Lightning attached external GPU that inherently outputs NTSC composite/EGA/TARGA-24. StackExchange is not a product-recommendation site, but I gotta imagine somebody makes or made such a thing, for old-school TV production if nothing else. Technologically, it would be little more than a dongle. Far cry from the stacked/stuffed TARGA-24 boards!

Then, appropriate video drivers so your Linux/Windows/Mac system can see it as "just another display" like it does with other GPUs.

This GPU certainly could maintain a 533++ x 400 internal buffer. With monochrome NTSC displays, there is no inherent limit to the number of horizontal lines, depending on how you feel about pixels being square. And if the display supports interlacing, you can also get 400 vertical resolution, although picture elements would need to be at least 2px wide (so they are present on both fields) or they would flicker.

Keeping in mind that most NTSC-era computers outputted a non-interlaced signal 200 pixels tall x 280-320 horizontal. Interlaced TVs were able to tolerate this. Most likely, your Apple IIc monitor has the same vertical sweep hardware as other TVs of the day, and would accept interlacing.

Answer 4

Creating a composite signal for a monochrome monitor should be quite easy.

I remember using 4 or 5 resistors to mix green, brightness, HSync and VSync from a 9-pin EGA output to construct a perfectly usable composite video signal.

You will probably not find CGA or EGA adapter in 2020, but the standard 15-pin VGA looks almost as easy.

The timing in VGA is programmable. 31.5kHz interlaced is trivial to construct as a modeline in Xorg and if you want Windows, a lot (all?) of video drivers have something resembling modelines in their INF files. HSync and VSync should be made positive.

The three luminosity signals of VGA are 0-0.7v @ 75 ohm that are acceptable in the composite signal, except that you have to mix in hsync/vsync at 1v and they come in TTL level. You'll have to use 2 diodes and a few resistors.

Answer 5

Raspberry Pi has composite video out built in. There's a QA here which has details relevant to configuration.

One of those with the appropriate adapter/cable may be the easiest way to get that old-fashioned experience you're looking for.

Answer 6

There are some solutions you could try. You can search for a monochrome VGA (actually they are multisync monitors. Search on ebay for an IBM 4707 or an IBM 8503/8504 for that 90s look. While you are at it and are lucky you could find a complete PS/2 you could use as a terminal or even try to run an older version of Linux of it (Model 90 were 486 and pentiums, so provider you have 80 floppies handy you colud install Slackware on it, as I did in the 90s). Otherwise old DOS terminal emulator are available.

VGA green monochrome monitors were avaliable at the time, but weren't so common, but there were some Olivetti models or some unknowns Taiwanese brands.

You could also use as a second monitor for your main computer. There were some monochrome super VGA monitors that were used in typographies, they are lesser iconic but they do the work too.

If you have a monochrome composite monitor, like the ones were used on Apple II and Commodore computers, you could use the composite out of a Raspberry Pi then attach a keyboard and you have another fully fledged computer with Linux on it.

You could force a "true" VGA to sync at NTSC or PAL frequencies, but it's tricky and depends on how the legacy part of the video board is made.