PICO9918: A drop-in replacement for a TMS9918A (with source)

[barnacle]

To be honest, I think that 640 x 480 is close to the limits for 8-bit technology without some external assistance - such as is happening with this PICO9918 or my Neolithic VGA; different approaches for different systems, but both using a video accelerator and memory not directly visible to the processor.

But that said, in the 70s and 80s designers were starting to use custom accelerators of one kind or another (until the IBM PC, of course, which started from scratch... but still had the video memory separate from the system memory, though directly accessible.

Neil

[cbmeeks]

In my design, I'm using "fat pixels" on a 640x480 to get 320x240. I also feel that 4096 colors (which is what I use) is the top limit for an 8bit design. It just seems much more than that you are crossing into the 16bit world.

[barnacle]

Yeah, I'm looking at a mostly-text mode display, so I need the higher resolution to make it usable for me. Colours are less important if I can't go 24-bit, though my Neo board includes an alternative gray-scale output.

Neil

[cbmeeks]

I managed to solder up V3. Like a moron, I did not order the stencil so I tried to put some solder paste by hand and then on the hotplate. That turned out to be a giant mess.

So I painfully hand-soldered those 0603 resistor networks.

Anyway, I get to the pin headers and I cannot make that work. Has anyone built V3? I'd like to see how it came together. The pin headers I have will not physically fit into the holes and it seems to not line up in a socket.

Thanks!

[visrealm]

It's designed for turned pin headers, not square. Mainly to increase the spacing between the Pico and TMS9918A pins, but also because they work better in a socket.

[cbmeeks]

Ah! Makes sense. I think I have some of those somewhere.

Thanks