Machine Specifics

The breakdown is as follows:

Processor: This is just the processor type. The 68LC040 is just like the 68040, but it is missing the FPU (Floating Point Unit, or math coprocessor) portion of the chip. The 68LC040 in any Mac can be replaced by a 68040, and the MacOS will recognize the presence of the FPU.

Gestalt: This is actually the mach gestalt. This is a number reported by the computer to allow software to recognize what type of machine it is running on. Sometimes when you speed up or slow down a Macintosh computer by clock chipping it, the mach gestalt changes. Sometimes it reports the number for a similar machine that uses an identical, but faster motherboard in which case everything is fine. But sometimes it reports a number for a machine that was never released to the public and for which some software will not work. In this case the mach gestalt reported needs to be faked, or software that has a problem with this needs to be modified. This was the case with the System 7.5 Update, and I wrote a patch to allow the software to run on the 7100's and 8100's where new mach gestalts were reported. See the Clock Chipping Software Incompatibilities page for more info on the software incompatibilities, and see Rene G. A. Ros' (rgaros@bio.vu.nl) Gestalt Selectors List for more info on gestalts.

Initial Oscillator (MHz): This is just the speed, in MHz, of the initial oscillator. It is the one that will need to be adjusted to speed up the machine.

Max Oscillator with serial (MHz): The serial ports have proven to be a limiting factor in clock chipping several of the 68040-class machines. If you do not need your serial ports, then you can sometimes run the machine a little faster. This is the speed of the oscillator you would use if you need to use your serial ports (modem and printer).

Max Oscillator w/o serial (MHz): This is the speed of the oscillator you would use if you did not plan on needing your serial ports.

Max Oscillator with PPC card & serial (MHz): The presence of a PPC card has also proven to be a limiting factor in clock chipping the 68040-class machines. This is the speed of the oscillator you would use if you plan to use both the PPC card and your serial ports.

Problems: These are the limiting factors that typically limit you from running the machine any faster that the speeds listed.

Centris 610	Processor: 68LC040@20MHz Gestalt: 52 Initial Oscillator (MHz): 10 Max Oscillator with serial (MHz): 14-14.31818 Max Oscillator w/o serial (MHz): 15 Max Oscillator with PPC card & serial (MHz): 14.2857 Problems: Serial Ports
Centris 650	Processor: 68040@25MHz Gestalt: 30 Initial Oscillator (MHz): 12.5 Max Oscillator with serial (MHz): 14.31818-14.7456 Max Oscillator w/o serial (MHz): 20 Problems: Serial Ports
Centris 650-mod	Processor: 68040@25MHz Gestalt: 36 Initial Oscillator (MHz): 12.5 Max Oscillator with serial (MHz): 19-20 Max Oscillator with PPC card & serial (MHz): 19.44755 Problems: Processor (crash)
Centris 660av	Processor: 68040@25MHz Gestalt: 60 Initial Oscillator (MHz): 12.5 Max Oscillator (MHz): 16-17.496 Problems: Video
Mac IIsi	Processor: 68030@20MHz Gestalt: 18 Initial Oscillator (MHz): 40 Max Oscillator (MHz): 50-55 Problems: Floppy Drive Controller
Mac IIfx	Processor: 68030@40MHz Gestalt: 13 Initial Oscillator (MHz): 80 Max Oscillator (MHz): 92.9405-100 Mac IIfx info
Mac LC475 (P475, P476)	Processor: 68LC040@25MHz Gestalt: 89 Gestalt at 20MHz: 86 Gestalt at 33MHz: 90 Q605 (LC475, P475, P476) Speedup
Mac LC575 (P575, P577, P578)	Processor: 68LC040@33MHz Gestalt: 92 Gestalt at 20MHz: 87 Gestalt at 25MHz: 91 LC575 (P575, P577, P578) Slowdown
Mac LC630 (P630, P635, P636, P638)	Processor: 68LC040@33MHz Gestalt: 98 Gestalt at 25MHz: 98 Gestalt at 40MHz: 98 Q630 (LC630, P630, P635, P636, P638) Speedup
Mac LCIII (P450)	Processor: 68030@25MHz Gestalt: 27 Gestalt at 33MHz: 62 LCIII (P450) Speedup
PowerBook 140	Processor: 68030@16MHz Gestalt: 25 Initial Oscillator (MHz): 33 Max Oscillator (MHz): 50
PowerBook 145	Processor: 68030@25MHz Gestalt: 54 Initial Oscillator (MHz): 50 Max Oscillator (MHz): 70
PowerBook 150	Processor: 68030@33MHz Gestalt: 115 Initial Oscillator (MHz): 66.6667 Max Oscillator (MHz): 86
PowerBook 160	Processor: 68030@25MHz Gestalt: 34 Initial Oscillator (MHz): 50 Max Oscillator (MHz): 66
PowerBook 170	Processor: 68030@25MHz Gestalt: 21 Initial Oscillator (MHz): 50 Max Oscillator (MHz): 66-70
PowerBook 180	Processor: 68030@33MHz Gestalt: 33 Initial Oscillator (MHz): 66.6667 Max Oscillator (MHz): 74.25
PowerBook 520(c)	Processor: 68LC040@25MHz Gestalt: 72 Initial Oscillator (MHz): 12.5 Max Oscillator (MHz): 20-22.5
PowerBook Duo 210	Processor: 68030@25MHz Gestalt: 29 Initial Oscillator (MHz): 50 Max Oscillator (MHz): 66
PowerBook Duo 230	Processor: 68030@33MHz Gestalt: 32 Initial Oscillator (MHz): 66.6667 Max Oscillator (MHz): 80
PowerBook Duo 280c	Processor: 68LC040@33MHz Gestalt: 103 Initial Oscillator (MHz): 66.6667 Max Oscillator (MHz): 86
PowerMac 6100/60(av) (P6110, P6112, P6115, P6116, P6117, P6118)	Processor: PPC 601@66MHz, but runs at 60MHz Gestalt: 75 Gestalt at 66MHz: 100 Gestalt at 80MHz: 101 Initial Oscillator (MHz): 30 Max Oscillator (MHz): 40-42 Problems: Processor
PowerMac 6100/66(av)(dos)	Processor: PPC 601@66MHz Gestalt: 100 Gestalt at 60MHz: 75 Gestalt at 80MHz: 101 Initial Oscillator (MHz): 33 Max Oscillator (MHz): 40-42 Problems: Processor
PowerMac 7100/66(av)	Processor: PPC 601@66Mhz Gestalt: 112 Gestalt at 60MHz: 111 Gestalt at 80MHz: 113 Initial Oscillator (MHz): 33 Max Oscillator (MHz): 40-42 Problems: Processor
PowerMac 7100/80(av)	Processor: PPC 601@80MHz Gestalt: 47 Gestalt at 66MHz: 112 Initial Oscillator (MHz): 40 Max Oscillator (MHz): 43 Problems: Processor
PowerMac 8100/80(av)	Processor: PPC 601@80MHz Gestalt: 65 Gestalt at 60MHz: 61 Gestalt at 66MHz: 64 Initial Oscillator (MHz): 40 Max Oscillator (MHz): 42-48 Problems: Processor
PowerMac 8100/100(av)	Processor: PPC 601+@110MHz, but runs at 100MHz, or PPC 601@100MHz Gestalt: 55 Gestalt at 80MHz: 65 Gestalt at 110MHz: 40 Gestalt at 120MHz: 12 Initial Oscillator (MHz): 33.3333 Max Oscillator (MHz): 42-42.9545 Problems: Video
PowerMac 8100/110(av)	Processor: PPC 601+@110MHz Gestalt: 40 Gestalt at 80MHz: 65 Gestalt at 100MHz: 55 Gestalt at 120MHz: 12 Initial Oscillator (MHz): 36.6667 Max Oscillator (MHz): 44-45 Problems: Video
PowerMac 8500/120	Processor: PPC 604@120MHz Gestalt: 69 Initial Oscillator (MHz): 40.000 Max Oscillator (MHz): 55 Problems: Video, processor, L2 Cache
PowerMac 9500/120	Processor: PPC 604@120MHz Gestalt: 67 Initial Oscillator (MHz): 40.000 Max Oscillator (MHz): 54 Problems: Video, processor
Quadra 605	Processor: 68LC040@25MHz Gestalt: 94 Gestalt at 20MHz: 93 Gestalt at 33MHz: 95 Q605 (LC475, P475, P476) Speedup
Quadra 610 (DOS)	Processor: 68040@25MHz Gestalt: 53 Initial Oscillator (MHz): 12.5 Max Oscillator with serial (MHz): 14.7456-15 Max Oscillator w/o serial (MHz): 18.5 Max Oscillator with PPC card & serial (MHz): 16.96 Problems: Serial Ports
Quadra 630	Processor: 68040@33MHz Gestalt: 98 Gestalt at 25MHz: 98 Gestalt at 40MHz: 98 Q630 (LC630, P630, P635, P636, P638) Speedup
Quadra 650	Processor: 68040@33MHz Gestalt: 36 Initial Oscillator (MHz): 16.6667 Max Oscillator with serial (MHz): 21-22 Max Oscillator w/o serial (MHz): 24 Max Oscillator with PPC card & serial (MHz): 19.6992 Problems: Serial Ports
Quadra 660av	Processor: 68040@25MHz Gestalt: 60 Initial Oscillator (MHz): 12.5 Max Oscillator (MHz): 16-17.496 Problems: Video
Quadra 700	Processor: 68040@25MHz Gestalt: 22 Initial Oscillator (MHz): 50 Max Oscillator (MHz): 66-70-74 Max Oscillator with PPC card (MHz): 74
Quadra 800	Processor: 68040@33MHz Gestalt: 35 Initial Oscillator (MHz): 16.6667 Max Oscillator with serial (MHz): 20-21 Max Oscillator w/o serial (MHz): 24 Max Oscillator with PPC card & serial (MHz): 19.286 Problems: Serial Ports
Quadra 840av	Processor: 68040@40MHz Gestalt: 78 Initial Oscillator (MHz): 20 Max Oscillator (MHz): 23- 24 Problems: Serial Ports
Quadra 900	Processor: 68040@25MHz Gestalt: 20 Initial Oscillator (MHz): 50 Max Oscillator (MHz): 66-70-74 Max Oscillator with PPC card (MHz): 74
Quadra 950	Processor: 68040@33MHz Gestalt: 26 Initial Oscillator (MHz): 66 Max Oscillator (MHz): 80-92.9405 Max Oscillator with PPC card (MHz): 80

Marc Schrier
(schrier@socs.berkeley.edu)