Subject: Re: [stella] smart multicart From: emooney1@xxxxxxxx (Erik K Mooney) Date: Mon, 25 Aug 1997 18:22:36 -0400 |
>Ok, now I have this thing in mind... please forgive me if it's a crap >idea, >I know just a little of electronics. > >Could a joystick port be used to switch banks of Rom memory? (remember >that >the joystick ports can be set for output.) > >Imagine a cart with a 64K Eprom, address lines 0-11 go to the VCS, and >12-15 to a DB9 connector plugged into the Player 2 joystick port (some >pull-down resistors could be needed). > >Each 4K bank would begin with the code to switch to the first bank >(for >bankswitched games), or to the bank with the game select menu (for a >multi >cart use). The VCS would switch banks writing to the register that >controls >the pins of the player 2 joystick port. > >Pros: minimum extra hardware needed >Cons: you lose one joystick port :) > >Is this a totally inpracticable idea? As someone else said, when you switched to another game, it would initialize the joystick ports, and you'd lose your bank setting. I suppose one could modify the code for each game to not initialize the DDR for the second joystick port; then, as long as the game doesn't try to output to the port (none should except Video Touch Pad games), it will work... though you're limited to one-player games (two with paddles.) I see possibilities to develop a standalone cart this way... that pretty much provides bankswitching for a ROM up to 64k, and the hardware would likely be simpler and cheaper (?) than Wilkson's 128k cart design. -- Archives updated once/day at http://www.biglist.com/lists/stella/archives/ Unsubscribing and other info at http://www.biglist.com/lists/stella/stella.html
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Re: [stella] smart multicart, Piero Cavina | Thread | Re: [stella] smart multicart, Chris Wilkson - MCD |
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