johnk@loki.atmos.ColoState.EDU (John Kleist) (07/25/90)
I recently (re)acquired an Apple ][+. My intent was to build a camera shutter tester for a friend who is a camera repairman. A photodiode and a transistor were connected to the game port. A little assembly for the timing loop (I love Big Mac) and some Applesoft for the rest. WOW! It works! I find that hacking on the Apple is FUN. Much more fun than banging away on a unix workstation or playing with my Amiga. This sort of fun is what originally attracted me to computing. Although GUI's, high level languages, and multitasking operating systems are wonderful things, they impede joyous hacking. Why type in pages of code when all you want to do is sample the high order bit at location $C062? I am now considering using it as a MIDI device. This would involve adding several A/D channels to set contoller values, building or buying a MIDI interface and possibly speeding up the CPU to handle contoller messages. I have several questions: 1) Has anyone built a A/D device for their Apple? I need 8 or 16 channels of 8-bit conversion at a moderate sampling rate, <1 khz. What chips are easy interface to a 6522 VIA? 2) Which of the MIDI interfaces will work with my Apple ][+? Are these easy to build? Do the commercial ones buffer incoming MIDI messages? Is MIDI interface programming similar to serial port programming? 3) Do these ZIP chip things really work? What is the REAL speed up factor on REAL programs, say a BASIC program? Do they somehow speed up memory access time as well as CPU cycles? John Kleist johnk@loki.atmos.colostate.edu
chm114u@vaxc.cc.monash.edu.au (07/27/90)
In article <8088@ccncsu.ColoState.EDU>, johnk@loki.atmos.ColoState.EDU (John Kleist) writes: > I recently (re)acquired an Apple ][+. My intent was to build a camera > [some interesting stuff deleted] > I am now considering using it as a MIDI device. This would involve adding > [more interesting stuff deleted] > 1) Has anyone built a A/D device for their Apple? I need 8 or 16 channels > of 8-bit conversion at a moderate sampling rate, <1 khz. What chips are > easy interface to a 6522 VIA? > Well, I've used an ADC0809, 8 channels, 8 bits, your programming will probably be the sampling time limit. A 6522 VIA and about seven 74series ttl logic chips and a handful or so of capacitors should round out the device. There are other adcs around that will (make that should) work just as well. > > 2) Which of the MIDI interfaces will work with my Apple ][+? Are these easy > to build? Do the commercial ones buffer incoming MIDI messages? Is MIDI > interface programming similar to serial port programming? > I haven't the foggiest notion! > 3) Do these ZIP chip things really work? What is the REAL speed up factor > on REAL programs, say a BASIC program? Do they somehow speed up memory > access time as well as CPU cycles? > I really liked my zip chip (when it finally arrived) but my GS arrived two weeks later. > > John Kleist johnk@loki.atmos.colostate.edu Mike.