You would be hard pressed to clock chip a //e or //c. You would have to be very mindful of the memory access times. Disk read/write and paddle/joystick routines are all software timing loops. On the //c, the serial port clock may be generated from the main CPU clock. IIRC, the video clock may also be generated from the CPU clock.
----- Original Message ----- From: "Philip Stortz" <[EMAIL PROTECTED]> To: "Apple2list" <[EMAIL PROTECTED]> Sent: Wednesday, November 17, 2004 04:11 AM Subject: Re: Apple IIc+ questions > So would it be possible to replace a crystal or oscillator on the logic board to clock chip it or > slow it down? i ask because i'm making a variable speed oscillator for clock chipping macs. > > it'll go to less than 1 mhz and can be varied in steps of 0.1 mhz or finer, on up to 133 mhz. it'll > connect to the serial port and be controllable by any dumb terminal program with simple commands, > and will respond with status as well. it will default on power cycling to a preprogrammed frequency > saved in eeprom which can be changed once a suitable frequency is found (or if set too high can be > reset by plugging it's serial interface into another computer). > > i'm designing it to connect with conductive epoxy (i'm repackaging it into smaller syringes to make > it cost effective) and it's barely larger than the normal oscillator, pinned out so that it can be > mounted on top of the old one. i'm in the middle of another project right now but should be back to > that project in a week or two and will hopefully have it done within a week of getting back to it. > i just have to write the code for it, i've already had the circuit boards made (3 small surface > mount chips, i'm using both sides of the board, very dense). > > i'm wondering if this would also be useful to people playing with the apple II line etc. i have a > iie myself that i'll be getting up later. > > just a thought, since people are doing hardware hacks on the older apple ii line as well as older > macs (and i'm considering some other apple ii projects eventually). i'm disabled but have some good > time and i'd love to come up with a couple of little products that make a little money and are > useful to people, low volume stuff since i don't have much to put into anything or a way to build in > large quantity. > > the apple II was the second computer i ever used, right after a timesharing system via 300 baud > decwriter II terminals and i've always loved them! even hand assembled some assembly code for one. > -- Apple2list is sponsored by <http://lowendmac.com/> and... / Buy books, CDs, videos, and more from Amazon.com \ / <http://www.amazon.com/exec/obidos/redirect-home/lowendmac> \ Support Low End Mac <http://lowendmac.com/lists/support.html> Apple2list info: <http://lowendmac.com/lists/apple2.html> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/apple2list%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
