From: Jim Brain (brain_at_jbrain.com)
Date: 2004-05-20 08:26:29
email@example.com wrote: >Hi Jim, > >The idea I've had is to use an EPROM. 8 address lines in, 8 datalines out. >One CIA drives the addresses (that is the one which outputs the scan value) >the other accepts the output from the EPROM. You might need diodes on the >datalines to create wired-AND with the joystick port. I expect this would be >compatible with most things, except for any software which tries to swap >which of the CIA outputs and which is the input... > > I'm intrigued, because I do not understand. I've seen EPROMs been used as address decoders, but in this case, the decode needs to change... You could create all possible combinations or 1 and 2 key presses as 8 byte maps, and use the controller for the high bits (select which map is decoded by manipulating AD9-15 of a 64 kB map. However, that's a lot of maps (I calc 1024 maps or so, which works in a 8KB EPROM, I suppose. Hwoever, I think there's some SW that scans the keyboard another way, so a one way solution would be unusable on those titles... I'm interested in more information on your idea, though, as I must be misunderstanding it. Jim >-----Original Message----- >From: firstname.lastname@example.org >[mailto:email@example.com]On Behalf Of Jim Brain >Sent: Thursday, 20 May 2004 10:28 AM >To: CBM Hackers >Subject: cross point switch > > >I am trying to build a keyboard eliminator that does not require a cross >point switch to "emulate" the 64/128 keyboard. However, in the event my >idea does not pan out, anyone know a part number for a 8x8 or so switch >that is not as big as the 40 pin monster on 64-KEYB? > >I'd like a plan B so my idea doesn't evaporate.... > >Jim > > > -- Jim Brain, Brain Innovations firstname.lastname@example.org http://www.jbrain.com Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.