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Technical Q&A HW97
Open Firmware Memory bus speed
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Q: Using Open Firmware, how can I tell the memory bus speed on a G3 or
G4 Macintosh?
A: On any Macintosh, navigate to the memory bus and dump its properties.
Display the clock-frequency property in decimal since the default display is
hexadecimal. Here is the code to do this:
Apple PowerMac1,1 1.1f4 BootROM built on 04/09/99 at 13:57:32
Copyright 1994-1999 Apple Computer, Inc.
All Rights Reserved.
OpenFirmware 3.1.1
To continue booting, type "mac-boot" and press return.
To shut down, type "shut-down" and press return.
ok
0 > dev / \ navigate to the memory node ok
0 > .properties \ display the properties
model PowerMac1,1
compatible PowerMac1,1
MacRISC
Power Macintosh
name device-tree
copyright Copyright 1983-1998 Apple Computer, Inc. All
Rights Reserved
device_type bootrom
system-id 0000000000000
#address-cells 00000001
#size-cells 00000001
clock-frequency 05f5e100
AAPL,add-fcode-file ff8199b0
ok
0 > 5f5e100 \ enter the clock-frequency property onto the stack
ok
1 > .s \ check just to make sure 5f5e100
ok
1 > cr ." the speed in Hertz is " .d
the speed in Hertz is 100000000 ok
0 >
The 100000000 Hz is 100 MHz.
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[Sep 22 2000]