atari2600land's Blog

SpiceWare · April 7, 2013

the CPU and ROM were combined - Microvision Cartridges

The Microvision is one of the few classic consoles that has not had the contents of it's cartridge ROMs dumped. Since the Microvision cartridges contain the systems microprocessor with an internal ROM, the data doesn't ever have to leave the chip making dumping problematic, but not necessary impossible.

There's no need to limit yourself to those CPUs, any CPU will do as log as you can wire it up to use the cartridge pinout to access the internal hardware (speaker, keypad, LCD, paddle).

atari2600land · April 8, 2013

I had thought that the game was stored inside this chip, which I assumed was the CPU. But could I store the game's ROM inside the CPU somehow? And can I still get TMS1100s? I bet Texas Instruments doesn't make them any more, do they?

EricBall · April 8, 2013

You can use any CPU to program it as the main unit has no brains. Personally, I'd use the Parallax Propeller, but there are probably other modern microcontrollers which could do the job.

Check out Dan B's Microvision page: http://atarihq.com/danb/Microvision.shtml see also http://www.handheldmuseum.com/MB/MicrovisionFAQ.txt

The cartridge connector is a 24 pin edge connection including 9V (battery) power and interfaces to the LCD controller, speaker, keypad & dial.

The trick is the LCD controller. As a custom part there isn't a lot of info on how it should be programmed (or even what voltage level the data lines need). But you might be able to get in contact with Gregg Woodcock or Dan Boris and see what they can give you.

However, programming this beast is going to be very, very low level as you are working basically at the hardware level. This is one reason I'd go with the Parallax Propeller: it has 8 CPUs on a single chip so you can dedicate a CPU to each task rather than trying to multiplex everything through interrupts. So one CPU would "read" the dial, a second would read the keyboard, a third would drive the LCD and a fourth would generate sound effects. A fifth CPU could handle the game logic and a sixth could be used to provide debug output via USB serial. You could even put on a microSD reader (CPU seven) so you could load games that way.