Editing Macintosh LC 630 DOS Compatible

{{Infobox computer
| name         = Macintosh LC 630 DOS Compatible
| image        = [[File:Macintosh_LC_630_front.jpg|250px]]
| caption      = Macintosh LC 630 DOS Compatible
| manufacturer = Apple Computer, Inc.
| type         = Desktop personal computer
| release date = April 3, 1995
| discontinued = March 2, 1996
| price        = US$1,899
| cpu          = Motorola 68LC040 @ 33 MHz + Intel 486DX2 @ 66 MHz
| memory       = 4 MB RAM on-board, expandable to 52 MB (two SIMM slots)
| storage      = 250 MB IDE hard drive, 2X CD-ROM drive
| display      = External monitor support (1 MB DRAM for video)
| sound        = Stereo 16-bit sound, SoundBlaster 16-compatible
| dimensions   = 4.3" H × 12.6" W × 16.5" D (109 × 320 × 419 mm)
| weight       = 19 lbs (8.6 kg)
| os           = System 7.1.2P – Mac OS 8.1; MS-DOS 6.22, Windows 3.1
| predecessor  = [[Macintosh LC 630]]
| successor    = [[Power Macintosh 6200]]
| codename     = Crusader
| model        = M3305LL/A
}}
The '''Macintosh LC 630 DOS Compatible''' is a dual-processor desktop computer released by Apple Computer, Inc. on April 3, 1995.<ref>{{cite web |url=https://en.wikipedia.org/wiki/Macintosh_Quadra_630 |title=Macintosh Quadra 630 |publisher=Wikipedia |access-date=2026-02-10}}</ref> It combines a Motorola 68LC040 processor running Mac OS with an Intel 486DX2/66 processor on a DOS Compatibility Card, allowing the system to run both Macintosh software and MS-DOS/Windows 3.1 applications natively.<ref>{{cite web |url=https://support.apple.com/en-us/112346 |title=Macintosh Performa 630CD DOS Compatible: Technical Specifications |publisher=Apple |access-date=2026-02-10}}</ref>

The LC 630 DOS Compatible was sold exclusively in the K-12 education market in the United States, priced at $1,899.<ref>{{cite web |url=https://lowendmac.com/1993/mac-lc-630-dos-compatible-and-performa-640/ |title=Mac LC 630 DOS Compatible and Performa 640 |publisher=Low End Mac |access-date=2026-02-10}}</ref> Consumer variants (Performa 630CD DOS Compatible, Performa 640CD DOS Compatible) were sold internationally.<ref>{{cite web |url=https://everymac.com/systems/apple/mac_lc/specs/mac_lc_630.html |title=Macintosh LC 630 (PC) Specs |publisher=EveryMac.com |access-date=2026-02-10}}</ref>

== Model Variants ==

The 630 DOS Compatible series includes several variants targeting different markets:

{| class="wikitable" style="width:70%"
|-
! Model !! Market !! RAM !! Storage !! Notes
|-
| LC 630 DOS Compatible || US K-12 Education || 8 MB || 250 MB || Intel 486DX2/66
|-
| Performa 630CD DOS Compatible || International Consumer || 8 MB || 500 MB || Not sold in US
|-
| Performa 640CD DOS Compatible || International Consumer || 8 MB || 500 MB || Bundled with monitor and modem
|-
| Quadra 630 DOS Compatible || Australia || 8 MB || 250 MB || Full 68040 with FPU
|}

Some units shipped with a Cyrix 486DX2/66 or Cyrix 486/70 processor instead of the Intel chip.<ref>{{cite web |url=https://lowendmac.com/1993/mac-lc-630-dos-compatible-and-performa-640/ |title=Mac LC 630 DOS Compatible and Performa 640 |publisher=Low End Mac |access-date=2026-02-10}}</ref>

== Dual Processor Architecture ==

The LC 630 DOS Compatible features a unique dual-processor design allowing true simultaneous operation of two operating systems:

=== Macintosh Processor ===

* '''CPU:''' Motorola 68LC040 @ 33 MHz
* '''FPU:''' None (68LC040 lacks floating-point unit)
* '''Bus Speed:''' 33 MHz
* '''L1 Cache:''' 8 KB integrated
* '''Data Path:''' 32-bit data, 32-bit address

The 68LC040 can be replaced with a full 68040 to add hardware floating-point support.

=== DOS Compatibility Card ===

The DOS Compatibility Card is a two-board assembly that installs in both the CPU socket and the LC PDS slot:<ref>{{cite web |url=https://tidbits.com/1995/06/19/its-a-mac-its-a-pc-its-dos-compatible/ |title=It's a Mac. It's a PC. It's DOS-Compatible! |publisher=TidBITS |date=1995-06-19 |access-date=2026-02-10}}</ref>

* '''CPU:''' Intel 486DX2 @ 66 MHz (or Cyrix equivalent)
* '''FPU:''' Integrated (486DX2 includes FPU)
* '''RAM:''' Dedicated SIMM slot, supports up to 32 MB (ships with 4 MB installed)
* '''Sound:''' SoundBlaster 16-compatible
* '''Game Port:''' PC-compatible joystick port
* '''Video:''' Shares Mac video output (no "hydra" cable required)

Unlike the Houdini II card used in the Power Macintosh 6100, the 630's DOS card shares the Mac's video port directly, simplifying cable management.

=== Card Architecture ===

The DOS card consists of two connected PCBs:
* '''Lower board:''' Plugs into the 68LC040 CPU socket
* '''Upper board:''' Connects to the LC PDS slot
* '''Joystick port:''' Mounted on the PDS connector section

This design leaves the Communication Slot and Video Input slot available for expansion.

=== CPU Upgrade Options ===

The DOS card's 486 socket supports upgrades with proper voltage adaptation:

{| class="wikitable" style="width:70%"
|-
! Upgrade CPU !! Compatibility !! Notes
|-
| Cyrix 5x86-100GP || Compatible || Recommended upgrade
|-
| Intel 486DX4-100 || Problematic || Windows 95 instability reported
|-
| AMD 5x86-133 || Problematic || Requires voltage interposer
|}

Voltage interposers are required for 3.3V processors (original socket supplies 5V). Projects like 486SocketBlaster and 486VRM provide open-source interposer designs.

== PC Setup Control Panel ==

The '''PC Setup''' control panel manages DOS card configuration from the Mac OS environment:<ref>{{cite web |url=https://tidbits.com/1995/06/19/its-a-mac-its-a-pc-its-dos-compatible/ |title=It's a Mac. It's a PC. It's DOS-Compatible! |publisher=TidBITS |date=1995-06-19 |access-date=2026-02-10}}</ref>

=== Features ===

* '''Drive Configuration:''' C: and D: drives stored as large Mac files
* '''RAM Allocation:''' Shared Mac RAM or dedicated DOS card RAM
* '''Hot-Key Switching:''' Command-Return toggles display between Mac and PC
* '''Printer Sharing:''' PC Print Monitor enables Mac printer access from DOS
* '''Serial Port Mapping:''' COM1/COM2 mapped to Mac serial ports

=== Software Versions ===

{| class="wikitable" style="width:70%"
|-
! Version !! Mac OS Support !! Notes
|-
| PC Setup 1.5 || System 7.1.2 – 7.5.3 || Original LC 630/640 version
|-
| PC Setup 1.6.4 || System 7.5.3 – 7.6.1 || Updated drivers
|-
| PC Setup 2.1.7 || Mac OS 8.5 – 9.2 || Third-party continuation
|}

== Memory and Storage ==

=== RAM Configuration ===

The DOS Compatible models feature two SIMM slots (versus one in standard LC 630):

{| class="wikitable" style="width:70%"
|-
! Location !! Type !! Maximum !! Notes
|-
| Soldered || On-board || 4 MB || Non-removable
|-
| SIMM Slot 1 || 72-pin, 80ns || 32 MB || Any standard SIMM
|-
| SIMM Slot 2 || 72-pin, 80ns || 16 MB || Single-sided SIMMs only
|-
| DOS Card || 72-pin, 80ns || 32 MB || Dedicated to DOS operations
|-
| '''Maximum System''' || || '''52 MB''' || 4 + 32 + 16 MB
|}

The DOS card can either use its dedicated RAM or share Mac motherboard memory. Dedicated RAM improves PC performance significantly.

=== Storage Systems ===

'''IDE Hard Drive:'''
* Single device support only (no master/slave)
* PIO Mode 3 maximum (11.1 MB/s)
* 8 GB addressing limit
* System 7.5.2+ required for modern IDE drives

'''CD-ROM:'''
* Apple CD 300i Plus (2X SCSI)
* Tray-loading mechanism
* Reads 656 MB and 748 MB data CDs
* Audio CD playback support

== Display and Graphics ==

The LC 630 DOS Compatible uses shared DRAM for video:

* '''Video Memory:''' 1 MB DRAM (soldered, not upgradeable)
* '''Video Output:''' DA-15 connector
* '''PC Video:''' Shares Mac video port (no separate monitor required)

=== Display Capabilities ===

{| class="wikitable" style="width:70%"
|-
! Resolution !! Color Depth !! Notes
|-
| 512 × 384 || 16-bit (32,768 colors) || Standard 12" RGB
|-
| 640 × 480 || 16-bit (32,768 colors) || VGA/13" RGB
|-
| 800 × 600 || 8-bit (256 colors) || SVGA
|-
| 832 × 624 || 8-bit (256 colors) || 16" monitor
|}

Video input not supported at 832×624 resolution.

== Audio Capabilities ==

The DOS Compatible adds SoundBlaster 16 compatibility to standard LC 630 audio:

'''Macintosh Audio:'''
* Stereo 16-bit sound output
* 44.1 kHz sampling rate
* Front headphone jack with volume buttons

'''DOS Audio:'''
* SoundBlaster 16-compatible expansion card included
* Full AdLib/OPL3 FM synthesis
* PC game audio support

== Input/Output and Expansion ==

=== Port Configuration ===

{| class="wikitable" style="width:70%"
|-
! Port !! Quantity !! Notes
|-
| ADB || 1 || Keyboard and mouse
|-
| Serial (Mini-DIN-8) || 2 || Printer and modem ports
|-
| SCSI (DB-25) || 1 || External devices, CD-ROM internal
|-
| Video (DA-15) || 1 || Shared Mac/PC output
|-
| Audio Line Out || 1 || Stereo mini-jack
|-
| Audio Line In || 1 || Stereo mini-jack
|-
| Headphone || 1 || Front panel, 3.5mm
|-
| Microphone || 1 || PlainTalk compatible
|-
| PC Game Port || 1 || 15-pin, joystick support
|}

=== Expansion Slots ===

* '''LC PDS:''' Occupied by DOS Compatibility Card
* '''Communication Slot:''' Available (supports modem or Ethernet)
* '''Video Input Slot:''' Available (supports Apple Video System Card or TV tuner)
* '''TV Tuner Slot:''' Available

== Design and Features ==

The LC 630 DOS Compatible uses the standard 630 case design with DOS card additions:

=== Front Panel ===
* Volume up/down buttons (first for Macintosh desktop)
* 3.5mm headphone jack
* Activity LEDs for power and drive access
* Infrared receiver (not used on standard LC 630)

=== Slide-Out Motherboard ===
* Rear panel opens downward
* Logic board mounted on sliding drawer
* Tool-free RAM and expansion access
* DOS card accessible without full disassembly

=== Included Software ===
* System 7.5.1 (Mac OS)
* MS-DOS 6.22
* Windows 3.1
* SoundBlaster drivers
* PC Setup control panel

== General Maintenance ==

For detailed maintenance procedures including cleaning, PRAM battery management, connector corrosion prevention, and voltage adjustments, refer to the dedicated [[Macintosh LC 630 General Maintenance]] page.

== PCB Schematics & Service Manual ==

The LC 630 DOS Compatible uses the standard 630 logic board (820-0524) with the addition of the DOS Compatibility Card. Service documentation available on the [[:Category:Apple Service Source|Apple Service Source]] page.

== Capacitor Replacement Guide ==

Detailed capacitor replacement guidelines for the logic board and DOS card can be found on the [[Macintosh LC 630 Capacitor Replacement Guide]] page.

== Troubleshooting ==

A comprehensive troubleshooting guide addressing power issues, video problems, DOS card specific issues, and Sad Mac errors is available on the [[Macintosh LC 630 Troubleshooting]] page.

== Technical Details ==

<templatestyles src="Template:StyledTable/styles.css" />

=== System Architecture at a Glance ===

{| class="wikitable styled-table" style="width:90%; text-align:center;"
! Sub-system !! Specification (Macintosh LC 630 DOS Compatible, April 1995)
|-
| '''Mac CPU''' || Motorola 68LC040 @ 33 MHz (no FPU)
|-
| '''PC CPU''' || Intel 486DX2 @ 66 MHz (integrated FPU)
|-
| '''Bus width''' || 32-bit data • 32-bit address
|-
| '''ROM''' || 1 MB
|-
| '''RAM''' || 4 MB soldered + 2 SIMM slots (52 MB max) + DOS card slot (32 MB max)
|-
| '''Video''' || 1 MB DRAM • 640 × 480 at 16-bit
|-
| '''Sound''' || Mac: 16-bit stereo • PC: SoundBlaster 16 compatible
|-
| '''Storage''' || IDE hard drive • 2X SCSI CD-ROM • 1.44 MB floppy
|-
| '''Ports''' || ADB, Serial × 2, SCSI, Video, Audio, PC Game Port
|}

=== Processor Specifications ===

{| class="wikitable styled-table" style="width:80%; text-align:center;"
|-
! Component !! Mac Processor !! DOS Card Processor
|-
| CPU || Motorola 68LC040 || Intel 486DX2
|-
| Clock Speed || 33 MHz || 66 MHz
|-
| FPU || None || Integrated
|-
| L1 Cache || 8 KB || 8 KB
|-
| Data Bus || 32-bit || 32-bit
|}

== Known Issues ==

=== Hardware Limitations ===
* Single IDE device support only
* PDS slot occupied (no additional LC PDS cards)
* Video memory not upgradeable
* DRAM video sharing causes performance penalty

=== Software Limitations ===
* DOS only—Windows NT, OS/2, Linux not supported
* System 7.5.1 or earlier cannot format modern IDE drives
* Some applications incompatible with dual-processor environment

=== Common Failures ===
* Surface-mount capacitors prone to leakage
* PRAM battery corrosion damages nearby components
* DOS card connector oxidation
* Brittle case plastics

== Service Documentation ==

The official Apple Service Source documentation for this model:

<pdf width="800" height="500">File:Quadra.lc_630.performa_640.pdf</pdf>

== See Also ==

* [[Macintosh LC 630 General Maintenance]] – Cleaning and preventive care
* [[Macintosh LC 630 Capacitor Replacement Guide]] – Complete specifications
* [[Macintosh LC 630 Troubleshooting]] – Diagnostic procedures
* [[Macintosh LC 630]] – Base model without DOS card
* [[Macintosh Quadra 630]] – Business variant with full 68040
* [[Macintosh Performa 630]] – Consumer variants
* [[Power Macintosh 6100]] – PowerPC model with DOS Compatibility option

== References ==

<references />

[[Category:Apple Vintage Computers]]