Macintosh Quadra 610 DOS Compatible
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal Computer |
| Released | February 28, 1994 |
| Discontinued | June 13, 1994 |
| Intro price | US$2,100 |
| CPU | Motorola 68040 @ 25 MHz (Mac) Intel 486SX @ 25 MHz (DOS) |
| Memory | 8 MB RAM (expandable to 68 MB Mac, 32 MB DOS) |
| Storage | 160 MB or 230 MB SCSI HDD |
| Display | DB-15 video port, up to 1152×870 @ 8-bit |
| Sound | 8-bit mono (Mac side only) |
| Dimensions | 3.4" H × 16.3" W × 15.6" D (8.6 × 41.4 × 39.6 cm) |
| Weight | 14 lbs (6.4 kg) |
| OS / Firmware | System 7.1 – Mac OS 8.1 |
| Predecessor | Macintosh Quadra 610 |
| Successor | Power Macintosh 6100 DOS Compatible |
| Codename | Speedbump 610 |
| Model no. | M2322LL/A |
The Macintosh Quadra 610 DOS Compatible is a dual-processor personal computer manufactured by Apple Computer and released on February 28, 1994.[1] It combines a Motorola 68040 processor running Mac OS with an Intel 486SX processor on a DOS Compatibility Card (internally codenamed "Houdini"), allowing the machine to run both Macintosh software and DOS/Windows applications.[2]
Apple produced approximately 25,000 units of the Quadra 610 DOS Compatible as a market test.[3] The product sold out within months of launch, demonstrating sufficient demand for Apple to develop successor products including the Power Macintosh 6100 DOS Compatible.
DOS Compatibility Card
The DOS Compatibility Card occupies the Processor Direct Slot (PDS) and contains:
- Intel 486SX processor running at 25 MHz
- One 72-pin SIMM slot supporting up to 32 MB RAM for DOS operations (80 ns or faster)
- 512 KB dedicated video RAM for DOS display
- PC game port connector
The card allows switching between Mac OS and DOS environments without rebooting. DOS video output is routed through the Mac's display port using a Y-adapter cable, or can be connected to a separate VGA monitor. The DOS card lacks sound capabilities; audio is not available in DOS mode.[4]
Architecture and Processor
Mac Side
The Macintosh side uses a Motorola 68040 processor at 25 MHz with integrated FPU. Unlike some Quadra 610 configurations which shipped with the 68LC040 (lacking FPU), all DOS Compatible models include the full 68040.[5]
- 32-bit data path
- 25 MHz system bus
- 8 KB L1 cache (integrated in CPU)
- 1 MB ROM
DOS Side
The Intel 486SX-25 processor on the DOS card provides:
- 32-bit architecture
- 25 MHz clock speed
- No integrated FPU (SX variant)
- Independent RAM via dedicated 72-pin SIMM slot
Memory and Storage
RAM Configuration
The logic board has 4 MB RAM soldered on-board with two 72-pin SIMM slots. Supported SIMM sizes are 4, 8, 16, and 32 MB, allowing a maximum of 68 MB total Mac RAM (4 MB onboard + 32 MB + 32 MB).
The DOS card's separate SIMM slot accepts one 72-pin SIMM up to 32 MB (80 ns or faster). DOS RAM is independent from Mac RAM.
Storage Systems
- Internal SCSI hard drive: 160 MB or 230 MB configurations
- 1.44 MB SuperDrive (auto-inject 3.5" floppy)
- Optional internal 2× CD-ROM drive (AppleCD 300i)
- External SCSI connector (DB-25) for additional devices
Display and Graphics
Mac Video
Built-in video with 512 KB VRAM (expandable to 1 MB via VRAM SIMMs):
| Resolution | 512 KB VRAM | 1 MB VRAM |
|---|---|---|
| 512×384 | 16-bit | 16-bit |
| 640×480 | 8-bit | 16-bit |
| 800×600 | 8-bit | 16-bit |
| 832×624 | 8-bit | 16-bit |
| 1024×768 | 4-bit | 8-bit |
| 1152×870 | 4-bit | 8-bit |
DOS Video
The DOS card includes 512 KB dedicated VRAM for DOS display output. Video can be displayed through:
- The Mac's DB-15 video port using the included Y-adapter cable
- A separate VGA monitor connected to the DOS card's output
Input/Output and Expansion
Port Configuration
- 2× ADB ports (keyboard and mouse)
- 2× Serial ports (printer and modem, mini DIN-8)
- 1× SCSI port (DB-25)
- 1× AAUI-15 Ethernet port
- 1× DB-15 video output
- 1× Audio output (3.5mm)
- 1× Microphone input (omni)
- 1× PC game port (DOS card)
Expansion
The PDS slot is occupied by the DOS Compatibility Card. A NuBus adapter (M1402LL/A) that would normally allow installation of a 7" NuBus card cannot be used with the DOS Compatible model.
General Maintenance
The Quadra 610 DOS Compatible shares the same base hardware and case design as the Macintosh Centris 610. For detailed maintenance practices including cleaning, PRAM battery management, connector corrosion prevention, and voltage adjustments, refer to the Macintosh Centris 610 General Maintenance page.
Capacitor Replacement Guide
Detailed capacitor replacement guidelines for the logic board can be found on the Macintosh Centris 610 Capacitor Replacement Guide page.
Troubleshooting
A comprehensive troubleshooting guide addressing no power, video issues, and other common problems is available on the Macintosh Centris 610 Troubleshooting page.
For DOS card-specific issues:
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| No DOS video | Y-cable not connected | Verify Y-adapter cable connections |
| Cannot switch to DOS | Card not seated properly | Reseat DOS card in PDS slot |
| DOS mode freezes | Insufficient DOS RAM | Install SIMM in DOS card slot |
| PC game port not working | Driver not loaded | Install PC Setup software from included disks |
Technical Details
System Architecture at a Glance
| Sub-system | Specification |
|---|---|
| Mac CPU | Motorola 68040 @ 25 MHz |
| DOS CPU | Intel 486SX @ 25 MHz |
| Bus width | 32-bit data |
| ROM | 1 MB |
| Max Mac RAM | 68 MB (72-pin SIMMs) |
| Max DOS RAM | 32 MB (dedicated SIMM) |
| Video | 512 KB – 1 MB VRAM (Mac), 512 KB (DOS) |
| Storage | SCSI HDD, 1.44 MB floppy |
| Networking | AAUI-15 Ethernet |
Identification
| Identifier | Value |
|---|---|
| Apple Order No. | M2322LL/A (160 MB HDD) |
| Model Number | M2113 |
| Gestalt ID | 53 |
| ROM ID | $067C |
| ROM Version | $23 |
See Also
References
- ↑ Macintosh Quadra 610 DOS Compatible: Technical Specifications, Apple Inc.—link(accessed 2026-02-10)
- ↑ Macintosh Quadra 610, Wikipedia—link(accessed 2026-02-10)
- ↑ One Box, Two Computers, Byte Magazine, April 1995—link(accessed 2026-02-10)
- ↑ Blast from the Past: A look back at Apple's DOS Compatibility Cards, Edible Apple, December 9, 2009—link(accessed 2026-02-10)
- ↑ Macintosh Quadra 610 (PC) Specs, EveryMac.com—link(accessed 2026-02-10)