Crystal Speedup History

Date: Fri, 8 Apr 94 01:01:04 PST From: Marc Schrier <schrier@garnet.berkeley.edu> Subject: [*] Crystal Speedup History 2.3 Mac Crystal Oscillator Speedup History 2.3 April 1994 There has been a great deal of interest expressed over the net about these simple and inexpensive Macintosh modifications that yield 20- 40% speed increases. Over the last year or so I have been doing a fair amount of crystal oscillator swapping/acceleration on Mac's, and gathering information from others. I've made several posts to comp.sys.mac.hardware with the bulk of this info and as new machines come out, and new concerns surface, I will try to add them to this history of the modifications, post them on comp.sys.mac.hardware and make them available for anonymous ftp on sumex-aim.stanford.edu in /info-mac/info/hdwr. Included in this version is some of the news on the PowerMac's and Marlin Prowell's new C650 modification. Please file in info-mac/info/hdwr Please remove the previous file, info-mac/info/hdwr/crystal-speedup-history-2.1 Mac Crystal Oscillator Speedup History 2.3 April 1994 There has been a great deal of interest expressed over the net about these simple and inexpensive Macintosh modifications that yield 20- 40% speed increases. Over the last year or so I have been doing a fair amount of crystal oscillator swapping/acceleration on Mac's, and gathering information from others. I've made several posts to comp.sys.mac.hardware with the bulk of this info and as new machines come out, and new concerns surface, I will try to add them to this history of the modifications, post them on comp.sys.mac.hardware and make them available for anonymous ftp on sumex-aim.stanford.edu in /info-mac/info/hdwr. Included in this version is some of the news on the PowerMac's and Marlin Prowell's new C650 modification. A little background: All computers operate at a certain frequency with which operations are performed. Within a certain class of computers, for example Mac's with a 68030 processor, the higher the frequency, the higher frequency of operations processed, and the faster the computer provided there is no other speed effecting hardware like a cache or slow data path. The designer of the computer, Apple in this case, will use components that are rated at the same frequency or faster than the final computer will be. The 68030's are made by Motorola. All 68030's are generally alike in what they do, but they are not alike in how fast they can do it. Motorola sells several 68030 processors rated at 16, 20, 25, 33, 40 and 50MHz for Mac's, accelerators and such. A large frequency difference will require a different mask during production of the processor, but small changes may not. Motorola only needs to guarantee that the chip they mark as 20MHz will function properly at 20MHz under a variety of conditions. Some chip vendors will test parts at different frequencies and sort the chips accordin…