There is also a C64 "slowdown" cart which attached the IRQ line to a timer and potentiometer. It would inject IRQ's to slow down, or pause, the running program. It was a simple cart circuit, and it had really odd effects on different games. On Fri, Jul 12, 2013 at 1:25 PM, Jim Brain <brain@jbrain.com> wrote: > I'm sure this is old news to most folks, but I was surprised. > > Leif Bloomquist gave me an old VIC-20 Expansion Unit (6 slot) that > contains a number of switches and knobs (it's really a cool unit, you can > select which banks the 2 RAM slots use via knobs, the normal ON/OFF per > slot, and some DIP switches for configs and a RESET button.). One > intriguing item on the PCB was a "PAUSE" switch. Dubious, I set the unit > up, popped in a GORF, and started the game. Just as the name suggests, > enabling the "PAUSE" button does indeed pause the game. > > I checked, and the switch just grounds IRQ. I suppose it makes sense, as > the CPU would continuously go to the IRQ routine, never moving forward in > the regular code, but it did surprise me. > > I didn't exhaustively test, but I worked on non cart apps as well. > > thought it odd that I've never seen a simple cartridge with a button > marketed for the VIC-20 as a "pause your game" aid. I would have thought > such a product would have been marketed. > > JIm > > -- > Jim Brain > brain@jbrain.com > www.jbrain.com > > > Message was sent through the cbm-hackers mailing list > > Message was sent through the cbm-hackers mailing listReceived on 2013-07-12 18:01:22
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