Over the summer time, chances are you’ll recall seeing a homebrew 6502 recreation console referred to as the GameTank grace those pages. The manufactured from [Clyde Shaffer], the device used to be impressively whole, really well documented, or even had a budding library of video games.
Lately, [Clyde] took to the r/electronics subreddit to sing their own praises the most recent growth to the GameTank: a revised detachable cartridge. The most important trade this time round is the addition of 32 KB of battery-backed SRAM that provides video games (or some other instrument that may well be at the cartridge) some power garage to paintings with.
Through the use of the 8th output little bit of the cartridge’s shift check in, instrument can transfer between getting access to the Alliance Reminiscence AS29CF160B 2 MB NOR flash chip (which is taking where of a conventional ROM) or SRAM. The higher part of the cart’s deal with area is all the time to be had, because it accommodates the 6502’s reset vector. However as soon as the device is up and operating, the decrease part of the flash may also be accessed by means of a sliding “window” in reminiscence that’s managed by means of the shift check in.
Including the backup energy supply most effective took the addition of a coin mobile and a pair diodes to verify it doesn’t intervene with the facility being equipped from the device when the cartridge is in use. Apparently [Clyde] notes that if a cartridge is put in within the GameTank when the facility is switched off, it may give sufficient juice to maintain the device’s RAM — so putting off the cartridge when now not in use is almost certainly a good suggestion.
The GameTank is an out of this world instance of a well-executed homebrew 6502 laptop, however after all the wonderful thing about operating with the long-lasting 8-bit microprocessor is how little it actually takes to get a device off the bottom. So when you’re having a look first of all one thing a little much less complicated, check out this unmarried breadboard implementation we lined just lately.