Power Macintosh G3: Technical Information Guide

This article contains the information published in the Power Macintosh G3 Technical Information Guide, which is included with every Power Macintosh G3 desktop system.
Processor

266 megahertz (MHz) PowerPC 750 processor/66 MHz system bus
233 megahertz (MHz) PowerPC 750 processor/66 MHz system bus
300 megahertz (MHz) PowerPC 750 processor/66 MHz system bus


Memory

Dynamic Random Access Memory
The computer comes with 32 megabytes (MB) of synchronous dynamic random-access memory (SDRAM), supplied in removable Dual Inline Memory Modules (DIMMs). The main logic board has three expansion slots which accept DIMMs that meet these specifications:Note: If you install DIMMs with different speeds, they will all operate at the speed of the slowest DIMM installed.

Important! Power Macintosh G3 series computers use Synchronous Dynamic Random Access Memory (SDRAM) DIMMs. DIMMs from older Macintosh computers are not compatible with your computer and should not be used even though they will fit into the DRAM DIMM slots.

To increase DRAM to the maximum of 384 MB, fill all three slots with 128 MB DIMMs.

(Editor's Note: The printed version of the Technical Information Guide does not contain this additional information: a Power Macintosh G3 in a desktop enclosure is capable of taking 128MB DIMMs. However, smaller 128MB DIMM's must be used due to space constraints. For additional information, refer to Tech Info Library article 24343, "Power Macintosh G3 (Desktop): 128MB Memory DIMM Support")

Video memory
Your computer comes with 2 MB of Synchronous Graphic RAM (SGRAM) video memory built into the logic board. The logic board contains a video memory expansion slot that accepts a DIMM to increase video memory up to a maximum of 6 MB. The DIMM must meet these specifications:Important! Use only SGRAM SO-DIMMS and never use 256K or 512K video memory DIMMs used in older Macintosh computers.

Other memoryFor more information and instructions on expanding your DRAM or video memory, see Chapter 3, "Installing PCI Expansion Cards and Additional Memory," in Setting Up Your Power Macintosh G3 series computer manual.

Graphics modes

The table that follows shows the modes available for monitors that can be connected to the monitor port, along with the number of colors or grays supported with 2 MB of video memory (SGRAM) and with the optional expansion to 4 MB or 6 MB of SGRAM. The table also lists the screen refresh rates in hertz (Hz) and kilohertz (kHz). Peripheral component interconnect (PCI) expansion cards that can support other monitors and special video requirements are available from other manufacturers. See your Apple-authorized dealer for information.

Note: On some monitors from manufacturers other than Apple, the connector pinout designates one pin for both green video and timing synchronization. These "sync on green" monitors are not compatible with Power Macintosh computers. If you're not sure what type of monitor you have, check with your dealer.

You can use the Monitors & Sound control panel or the Control Strip to set a display mode that is supported by both your monitor and the built-in video circuitry. Refer to the manual that came with your monitor for a list of display modes that it supports.

Display Modes and Color Depths
Display Mode
Screen Refresh Rate
Clock
Pixel Color Depth (bits per pixel)*
(resolution)
vertical
horizontal
2MB
4MB
6MB
512 x 384
70.130 Hz
31.488 kHz
21.160
32
32
32
640 x 480
59.940 Hz
31.469 kHz
25.175
32
32
32
640 x 480
66.667 Hz
35.000 kHz
30.24
32
32
32
640 x 480
72.809 Hz
37.861 kHz
31.500
32
32
32
640 x 480
75.000 Hz
37.500 kHz
31.500
32
32
32
640 x 480
85.008 Hz
43.269 kHz
36.000
32
32
32
640 x 870
75.000 Hz
68.850 kHz
57.283
16
32
32
800 x 600
56.250 Hz
35.156 kHz
36.000
32
32
32
800 x 600
60.317 Hz
37.879 kHz
40.000
32
32
32
800 x 600
72.188 Hz
48.077 kHz
50.000
32
32
32
800 x 600
75.000 Hz
46.875 kHz
49.500
32
32
32
800 x 600
85.061 Hz
53.674 kHz
56.250
32
32
32
832 x 624
74.550 Hz
49.725 kHz
57.283
32
32
32
1024 x 768
60.004 Hz
48.363 kHz
65.000
16
32
32
1024 x 768
70.069 Hz
56.476 kHz
75.000
16
32
32
1024 x 768
75.029 Hz
60.023 kHz
78.750
16
32
32
1024 x 768
74.927 Hz
60.241 kHz
80.000
16
32
32
1024 x 768
84.997 Hz
68.677 kHz
94.500
16
32
32
1152 x 870
75.062 Hz
68.681 kHz
100.00
16
32
32
1280 x 960
75.000 Hz
75.000 kHz
126.000
8
16
16
1280 x 1024
60.020 Hz
63.981 kHz
108.000
8
16
32
1280 x 1024
75.025 Hz
79.976 kHz
135.000
8
16
16
1280 x 1024
85.024 Hz
91.146 kHz
157.500
8
16
16
1600 x 1200
60.000 Hz
75.000 kHz
162.000
8
16
16
1600 x 1200
65.000 Hz
81.250 kHz
175.500
8
16
16
1600 x 1200
70.000 Hz
87.500 kHz
189.000
8
16
16
1600 x 1200
75.000 Hz
93.750 kHz
202.500
8
16
16
The following five configurations are available only on Power Macintosh G3 computers with the revision 2 logic board:
1280 x 960
75.000Hz
75.000kHz
126.000MHz
8
16
32
1280 x 1024
75.025Hz
79.976kHz
135.000MHz
8
16
32
1280 x 1024
85.024Hz
91.146kHz
157.500MHz
8
16
32
1920 x 1080
59.994Hz
70.313kHz
180.000MHz
8
16
16
1920 x 1080
71.992Hz
84.375kHz
216.000MHz
8
16
16
Table Notes:
* This mode is derived from VESA 640 x 400 timings (used primarily as a games mode).
Image bit depths:
32 bits=millions of colors
16 bits=thousands of colors
8 bits=256 colors


Internal disk drives

The following drives come factory-installed in your computer:
Interfaces
Optional audio/video interfaces

Some Power Macintosh G3 models include the following audio/video interfaces:All the video ports support the NTSC and PAL video standards. The video input ports also support the SECAM video standard.

SCSI interface

Your computer has one standard SCSI chain, which is capable of transferring data at up to 5 MB per second. The SCSI chain can support up to seven internal and external SCSI devices. This section describes the internal SCSI expansion options. For information on connecting external SCSI devices, see Setting Up Your Power Macintosh G3 Series Computer manual. An Apple-authorized dealer or service provider can install internal SCSI devices.

The computer has two internal expansion bays. Each one accepts a 3-1/2" or 5-1/4" storage device that is up to 1.625" (41.3 mm) high. Some models come with a Zip drive already installed in one of these bays. An Apple-authorized dealer or service provider can install internal SCSI devices, along with any necessary data cabling or brackets to properly secure each SCSI device inside the computer. (Models with an internal Zip drive have an internal SCSI cable that includes an extra SCSI connector for the second expansion bay. Models without an internal Zip drive do not come with an internal SCSI cable; a dealer or service provider must install a SCSI cable in order to connect internal devices to the SCSI chain.) An Apple-authorized dealer or service provider could also replace the CD-ROM drive with a 5.25-inch (or smaller) device as tall as 1.625 inches (41.3 mm), or replace the floppy disk drive with a 3.5-inch device as tall as 1.04 inches (26.0 mm).

All internal and external devices on the SCSI chain must have unique ID numbers. SCSI ID numbers 0 through 6 are available. If the computer came with an internal Zip drive, the drive already has SCSI ID number 5 assigned to it. The computer itself has been assigned SCSI ID number 7.

Important Some older SCSI devices may require updated drivers to work with your computer. (A "driver" is special software that is installed in your System Folder.) Contact the device manufacturer for information on obtaining driver software.

Clock/calendar

CMOS custom circuitry with long-life battery

Keyboard

Supports all Apple Desktop Bus (ADB) keyboards

Mouse

Supports all models of the ADB mouse

Audio system

Custom sound circuitry, including a stereo generator (digital-to-analog converter, or DAC) capable of driving stereo miniplug headphones or audio equipment and stereo sampling hardware (analog-to-digital converter, or ADC) for recording stereo sound.Warning! Do not attempt to replace the clock battery yourself. If the clock begins to lose accuracy, have an Apple-authorized service provider replace the battery. The service provider will dispose of the battery according to the local environmental guidelines.

Typical audio specifications

Sound input using the sound input portSound output using the sound output portNoise, Distortion, and BandwidthAC line input
AC line output
DC power

Continuous output: 161 W
Peak output (for 12 seconds at startup): 210 W
Output voltage
Maximum current
+5V
18.3A
+5V (trickle)
0.1A
+3.3V
12.5A
+12V
6.2A
-12V
0.4A

-- Total continuous power output cannot exceed 161 W.
-- Not more than 104 W total combined power.

Apple Desktop Bus (ADB)

The mouse draws up to 10 milliamperes (mA).
The keyboard draws 25­80 mA (varies with keyboard model used).
The maximum current available for all ADB devices is 500 mA.
The ADB port can support up to three ADB devices.

Audio and telecommunications devices

The following table shows power allowances for external devices connected to input ports.
Device
Voltage
Current
Power
Microphone
+5V
20mA
100mW
A device connected to the printer port or modem port
+5V
500mA
2.5W



Expansion cards and other internal devices

If you add an expansion card or a 3.5-inch storage device to your computer, make sure the component's power requirements don't exceed the maximum power allowances allocated to it by the computer.
The maximum power allowances for expansion cards in your computer can accommodate three 15-watt, two 25-watt cards, or one 15-watt card and one-25 watt card. Some detailed guidelines are presented in the following table.

Device
Voltage
Current
Power
Expansion card (15 watts)*
+5V
3A
15W
+12V
0.500A
6W
-12V
0.100A
1.2W
+3.3V
2A
6.6W
Expansion card (25 watts)**
+5V
5A
25W
+12V
0.500A
6W
-12V
0.100A
1.2W
+3.3V
2A
6.6W
Storage devices (such as a hard disk)
+5V
3A
15W
+12V
2.3A
27.6W
+12V
6.2A peak***
-
Notes:
* 15-watt expansion cards should not consume more than 15 watts of total power.
** 25-watt expansion cards should not consume more than 25 watts of total power.
*** Peak power is for startup only and must not occur in normal operation.

CD-ROM drive

Disc speedDisc diameters supportedData capacityModes supported
Published Date: Feb 18, 2012