EF9365 / EF9366 / EF9367 video

A look at the EF9365 / EF9366 / EF9367 video chips

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Just a collection of information about this chip and boards that use it. So far, I'm only aware of two boards, the GDP-64 by Rolf-Dieter Klein and the Elektor high-resolution colour graphics board.

The Elektor board is a more convenient sized 160x100mm Eurocard, and is extensively documented in various language editions of the magazine, so it is the better design.

The pixel clock is 12 or 14 MHz. The pixels are not exactly square, but that is only desirable in pixel graphics.

Most television circuits would not have the bandwidth or phosphor-dot density to support 80-column text. A monitor would be a wiser option, if you can get one.

The chip itself is not great. Its predecessor the EF9345 was only a text video sequencer, and the EF6366 is only a graphics video sequencer that draws text on a graphic screen.

Not suited for new designs.

In Rolf-Dieter Klein's book, Mikrocomputer Selbstgebaut Und Programmiert, page 264, there is some Z80 source code for the EF9364, which I assume is a very close predecessor to the EF9365. German comments.

If I wanted to experiment with this chip I would buy a modern reproduction of the GDP-64 board and interface its bus to whatever other bus I was using, or recreate the Elektor board.


Source code made by adding information from the article to the disassembly. Assembles online at and binary output verified the same as the original 1200 baud ROM. NB the magazine listing has 9600 baud.

text/plain - 110.40 kB - 04/03/2022 at 03:49


The MC magazine Graphic Terminal article quickly converted to html. Some errors may be present but you can get the gist of what is going on.

application/zip - 1.50 MB - 04/03/2022 at 00:29



MC graphic terminal firmware disassembly. Some of the code is actually data.

plain - 123.48 kB - 04/02/2022 at 15:12



MC graphic terminal firmware hex file.

hex - 22.51 kB - 04/02/2022 at 15:13



MC graphic terminal firmware binary file.

octet-stream - 8.00 kB - 04/02/2022 at 15:13


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fjkraan wrote 04/02/2022 at 12:44 point

For a very long time, I have a Z80/EF9366P based graphical terminal eurocard-board for the ECB bus, but it only uses the power lines. The upper half looks very much like your boards, a Z80 with memory takes the other half. It has RDK as initials on the board, so it is very related. It was described in two MC-magazine articles:

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Keith wrote 04/02/2022 at 12:52 point

Thanks for the info. These are not "my" boards, but R.D. Klein's. I had a look at your pdf and largely converted it to html so google can translate it. Only taking the power lines from the bus makes it easy to port to other buses :-)

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ljheidel wrote 01/09/2022 at 12:08 point

I've done a "new design" with this chip's predecessor (EF9345)  for Z-80 retrocomputing.  It's "not great" but it looks like it will be good for basic 80 column video since I was able to get it working with only 5 chips (2 of which were already present in my system).  It took me about a day to figure out how to interface it and build the circuit.  Still working on the software.  I've written a rudimentary C library, and built some ASM code that's going into my CP/M BIOS, but it's a work in progress.

I have an older Dell 20" LCD display that was pretty fancy for it's day.  With a little bit of coaxing, it will sync up to this at both 50Hz PAL and 60Hz NTSC timings through the VGA port with nothing to interface it but voltage-dividing resistors on the RGB lines.  It scales the picture, so it doesn't look great, but it works.  I'm looking for a better solution.  This would preclude it from being used comfortably for any length of time.

If you're interested, I can share my code, design and notes.

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Keith wrote 01/09/2022 at 20:51 point for that chip.
It was used for the Dutch Acorn Atom Club's 80-column card.

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