The hardware is the Z80-based Sega Master System and Game Gear.
Due to the design, it was a huge, messy, poorly written series of hacks that could just about produce the above result if you didn't breathe too hard.
After finding this document, I had a bit of a blast at rearranging the Z80 core and timing the video hardware a bit more correctly. Here's that old Fire Track project:
All this does is run the emulation for 100 scanlines on a Timer's tick, hence the low reported clock speed.
The Game Gear's LCD cropped the output screen, so you wouldn't see the junk to the sides of the display here.
My implementation of the VDP doesn't support sprites yet.
Of course, these are the most exciting screenshots:
Two versions of ZEXALL, one that displays the results on the SMS screen, the other in an SDSC debug console.
One day I shall purge all of these CRC errors. One day! But not now, as I don't have the time to put any work on this (I stole a couple hours for the above), and in spare time (hah!) I should really focus on the Latenite software. Which, whilst it doesn't provide such pretty screenshots, is a great deal more useful.