Macintosh Quadra 900
 | |
| Macintosh Quadra 900 | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal Computer |
| Released | October 21, 1991 |
| Discontinued | May 18, 1992 |
| Intro price | US$7,200 |
| CPU | Motorola 68040 @ 25 MHz |
| Memory | 4 MB RAM (expandable to 256 MB) |
| Storage | 160 MB or 400 MB SCSI hard drive, 1.44 MB floppy |
| Display | DB-15 video output, 1 MB VRAM (expandable to 2 MB) |
| Sound | 8-bit stereo output, mono input |
| Dimensions | 18.6" H × 8.9" W × 20.6" D (47.2 × 22.6 × 52.3 cm) |
| Weight | 36.8 lbs (16.7 kg) |
| OS / Firmware | System 7.0.1 – Mac OS 8.1 |
| Predecessor | Macintosh IIfx |
| Successor | Macintosh Quadra 950 |
| Model no. | M4200 |
The Macintosh Quadra 900 is a personal computer designed and manufactured by Apple Computer, released on October 21, 1991.[1] It was introduced alongside the Quadra 700 as the first computers in the Quadra family using the Motorola 68040 processor.[2]
The Quadra 900 was Apple's first Macintosh in a tower case form factor, designed for use as a departmental server or high-end workstation. It was discontinued after approximately six months in favor of the Quadra 950, which features a 33 MHz processor and improved graphics support.
Architecture and Processor
The Quadra 900 uses a Motorola 68040 processor running at 25 MHz with an integrated FPU and 8 KB of Level 1 cache. The 68040 is a full 32-bit processor with 32-bit data and address buses.
The system bus runs at 25 MHz. The clock input runs at 50 MHz, but the processor itself operates at 25 MHz (not clock-doubled).
Memory and Storage
RAM Configuration
The Quadra 900 has 16 30-pin SIMM slots supporting 80 ns RAM modules. RAM must be installed in groups of four identical SIMMs. Apple officially supported 64 MB, but third-party configurations achieved 256 MB using sixteen 16 MB SIMMs.[3]
Standard configuration shipped with 4 MB of RAM.
ROM and System Software
The Quadra 900 includes a 1 MB ROM. It shipped with System 7.0.1 and supports Mac OS versions up to 8.1. It is the earliest Macintosh model capable of running Mac OS 8.
Storage Systems
The system uses a SCSI interface for storage. Factory configurations included either no hard drive, a 160 MB, or a 400 MB SCSI hard drive. A 1.44 MB SuperDrive floppy drive is standard.
A front-facing 5.25" drive bay is available for a CD-ROM drive, tape backup, or SyQuest drive. Two additional internal 5.25" bays are available (three if no hard drive is installed).
Display and Graphics
The Quadra 900 includes integrated video with a DB-15 connector. Standard VRAM is 1 MB, expandable to 2 MB via four 256K VRAM SIMM slots (80 ns).
Display resolutions supported:
- 512×384 at 24-bit color (1 MB VRAM)
- 640×480, 832×624, 1152×870 at 8-bit color (1 MB VRAM)
- Up to 832×624 at 24-bit color (2 MB VRAM)
- 1152×870 at 8-bit color (2 MB VRAM)
Additional displays can be supported via NuBus video cards.
Audio Capabilities
The Quadra 900 features:
- 3.5mm stereo output jack
- 3.5mm mono input jack
- 8-bit audio
Input/Output and Expansion
Port Configuration
- 1× Apple Desktop Bus (ADB) port
- 2× Serial ports (printer and modem)
- 1× DB-25 SCSI port
- 1× AAUI-15 Ethernet port (built-in)
- 1× DB-15 video output
- 3.5mm audio input and output jacks
Expansion Slots
The Quadra 900 provides extensive expansion options:
- 5× NuBus slots (three provide 15W, two provide 25W power)
- 1× 68040 Processor Direct Slot (PDS)
Upgrade Options
Apple offered a Quadra 950 logic board upgrade for $1,899 and a Workgroup Server 95 upgrade for $2,499. With the Power Macintosh Upgrade Card installed, the system runs at 50 MHz and identifies as "Power Macintosh 900" in System Profiler.
Design and Features
The Quadra 900 uses a mid-tower case measuring 18.6 inches (47 cm) tall. The case design was shared with the Quadra 950 and Workgroup Server 95.
A three-position key-lock on the front panel provides security options:
- Off – Machine cannot be powered up
- On – Normal operation
- Secure – Floppy drive and ADB port are disabled
Power supply provides up to 303W and accepts 100-240V AC at 50-60 Hz.
General Maintenance
For detailed maintenance practices including cleaning, PRAM battery management, connector corrosion prevention, and voltage adjustments, refer to the dedicated Macintosh Quadra 900 General Maintenance page.
Capacitor Replacement Guide
Detailed capacitor replacement guidelines can be found on the Macintosh Quadra 900 Capacitor Replacement Guide page.
Troubleshooting
A comprehensive troubleshooting guide addressing power issues, video problems, and error codes is available on the Macintosh Quadra 900 Troubleshooting page.
Technical Details
System Architecture at a Glance
| Sub-system | Specification (Macintosh Quadra 900, 1991) |
|---|---|
| CPU | Motorola 68040 @ 25 MHz |
| FPU | Integrated |
| L1 Cache | 8 KB |
| Bus width | 32-bit data • 32-bit address |
| Bus speed | 25 MHz |
| ROM | 1 MB |
| RAM | 4 MB standard, 256 MB maximum (16× 30-pin SIMM slots) |
| Video | 1-2 MB VRAM, up to 1152×870 |
| Sound | 8-bit stereo output, mono input |
| Storage | SCSI hard drive, 1.44 MB floppy |
| Expansion | 5× NuBus, 1× PDS |
| Ports | ADB, 2× Serial, SCSI, AAUI-15 Ethernet, DB-15 video |
See Also
- Macintosh Quadra 700 – Desktop Quadra released the same day
- Macintosh Quadra 950 – Direct successor with 33 MHz processor
- Macintosh IIfx – Predecessor high-end Macintosh