Bryan Parkoff wrote:
<heuser.marcus@freenet.de> wrote in message 1137093322.834215.67540@z14g2000cwz.googlegroups.com">news:1137093322.834215.67540@z14g2000cwz.googlegroups.com...I'm certainly not here to criticize anyone - especially not one with some rather creative ideas - but I strongly recommend that you read one or both of the following excellent books to better understand the hardware you are dealing with: "Understanding the Apple II" by Jim Sather "The Apple II Circuit Description" by Winston D. Gayler bye MarcusMarcus,Thank you. I have Understanding the Apple II + //e" manual already. Try to imagine if you replace ROM and RAM chips to support 4MHz instead of 2MHz. You will be able to run 6502 CPU at 2MHz on Apple II+ while video is still running at 14M with no problem. It would affect Disk II, sound, and slots. I have no idea if video scanner is affected that it is supposed to access RAM at 2MHz. You imagine that it may not work! It is like a hack without using accelerator card.
Apple accelerated the Apple II twice--once in the IIc+ with a Zip Chip clone design, and once in the IIgs with shadow RAM. Preserving the compatibility that makes a hack interesting imposes many constraints that keep it from being simple. The Apple II is a remarkably clever intertwining of constraints and capabilities that achieved unprecedented "bang for the buck" when it was designed. Ironically, that very cleverness makes it much more difficult to just "speed up the clock" and still have an Apple II. -michael Music synthesis for 8-bit Apple II's! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it is seriously underused."