It all started in fall of 2022, when I was watching This Does Not Compute’s video on the history of graphing calculator gaming. Around the 5 minute mark, he offhandedly mentions the kind of processors TI’s graphing calculator line uses. Most of them use the Z80, the 89 and 92 use the M68K, and the Nspire line uses an ARM-based processor.
That really piqued my interest, since I already knew the processors that Sega’s retro game consoles used: The Z80 for the Master System, and the M68K for the Genesis. The calcs have a grayscale screen, but I wanted to know if anyone ever tried porting a Sonic game from the consoles to one of the calcs.
↫ grubbycoder
Right off the bat, after settling on the most appropriate graphing calculator to try and port Sonic 2 to, namely the TI-84+ CE with a 48Mhz eZ80 processor (“basically a 24-bit Z80”), 256 KB of RAM and a 320×240 display, the porting process runs into some serious roadblocks before any code’s even been written. Unlike the Sega hardware Sonic 2 runs on, the TI-84+ CE has no graphics hardware, the clock speed is effectively crippled at 12-20Mhz, a file format with a size limit of 64KB per file.
The rest of the story details the many difficulties that needed to be overcome, but in the end, the port is completed – and yes, you can now play Sonic 2 from the Master System on a TI graphing calculator.
Really cool piece of work, thanks for posting Thom
Especially enjoyed revisiting the Master System VDP internals. As a MS emulator author it brought back memories (shameless plug, https://github.com/PhilPotter/MasterEmu for anyone who is interested).