I'm designing a 8080 processor based computer and I want it to be able to at least output something visually.

I have thought about using SMD LED matrix made by myself, but even with the 160 x 120 px it would cost about $65 for the LEDs themselves, and I'm trying to be as cheap as possible here, plus that requires a ton of soldering, so that's not the best idea.

The second one of my ideas would be to use a soviet CRT oscilloscope tube 6ŁO1I, but that requires generating X and Y signals and synchronising them together with the modulation of brightness, and that is also pretty complicated, at least for me.

I want the display to be serviced by a DMA controller accessing the part of RAM that is not entirely free to use because its addresses would correspond to EPROM adresses (writing to them would cause the data to be written into the RAM and reading would read from EPROM, unless an addressable D-latch is triggered, so the RAM can be read form the "EPROM region". And finally, I heard about Intel's 8275 CRT controller and that it's possible to use it as a composite video output, however I lack the knowledge about TV signals and i am afraid i wouldn't be able to make it work properly.

Can anyone help me with that? I know it's an ambitious project and I'm working on certain parts of it individually, but I need to think about everything at once too so I don't forget about implementing something crucial for the operation of the machine it might become.

Thank you for any answer.

  • 2
    \$\begingroup\$ This type of question doesn't really meet EESE's mission for specificity. Just as historically, the simplest solution may be to use a serial line connecting an external terminal. In terms of modern options, there are now a lot of LCD and OLED displays intended for Arduino-type projects which you may be able to use - with the advantage that those having controllers do not need to be refreshed, but only require attention when changed. Decide if you would rather use a parallel interface or something like SPI or I2C. Understand how an Arduino would use the display before buying it for your 8080. \$\endgroup\$ – Chris Stratton Sep 29 '18 at 21:54
  • \$\begingroup\$ Or consider a tele-typewriter (TTY.) It would be era-appropriate. \$\endgroup\$ – rdtsc Sep 29 '18 at 22:25
  • \$\begingroup\$ The Ferguson Big Board has an integrated character-based display controller that uses 2KB of bank-switched RAM as a display buffer. The original design is intended to drive a "TTL" CRT monitor (which were common back then), but it would be easy to modify the design to drive a modern LCD monitor with a VGA interface. \$\endgroup\$ – Dave Tweed Sep 29 '18 at 23:08

You should find plenty of ideas with a web image search.

enter image description here

Photo 1. 8080 board with retro seven-segment display and optional 20 x 2 serial LCD display. Source: kswichit.com.

The linked article has full schematics, code, hints on terminal emulation, etc.

It's well worth studying these schematics to figure out how the systems worked in the old days. You then get a better feel for how some of the internals of the integrated micro-controllers work today.

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