ADC Home > Reference Library > Technical Q&As > Hardware & Drivers > Apple Hardware >

Open Firmware Memory bus speed

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.
0 > dev /            \ navigate to the memory node  ok
0 > .properties         \ display the properties
model                       PowerMac1,1
compatible              PowerMac1,1
                                  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
0 > 5f5e100            \ enter the clock-frequency property onto the stack
1 > .s                 \ check just to make sure 5f5e100
1 > cr ." the speed in Hertz is " .d
the speed in Hertz is 100000000  ok
0 >
The 100000000 Hz is 100 MHz.

[Sep 22 2000]

Did this document help you?
Yes: Tell us what works for you.
It’s good, but: Report typos, inaccuracies, and so forth.
It wasn’t helpful: Tell us what would have helped.