RetroTechCollection

Apple LaserWriter II SC

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The Apple LaserWriter IISC was an entry-level laser printer in the LaserWriter II series, released in January 1988 at US$2,999. Unlike other LaserWriter models, the IISC eliminated PostScript support and LocalTalk networking to reduce costs, instead using SCSI for connectivity and relying on the host Macintosh's QuickDraw to rasterize pages. The printer used a Canon LBP-SX print engine and featured a slower Motorola 68000 processor running at 7.45 MHz with only 1 MB of RAM. The IISC included dual SCSI ports for daisy-chaining and an ADB port for future expansion that was never utilized. The printer was discontinued in July 1990, replaced by the Personal LaserWriter SC.

Apple LaserWriter IISC
Apple LaserWriter IISC (1988)
Manufacturer Apple Computer, Inc.
Type Laser printer
Discontinued July 1, 1990
Price US$2,999 (1988 retail)
Interface SCSI (dual ports), ADB
Compatible Macintosh with SCSI
Dimensions 8.7" H × 20.2" W × 18.7" D
Weight 45 lbs (20.4 kg)
Model M6000
Power 900W maximum, 90-126V/50-60Hz

Technical Specifications

Physical Specifications

  • Dimensions: 8.7" H × 20.2" W × 18.7" D (221 × 513 × 475 mm)
  • Weight: 45 lbs (20.4 kg)
  • Operating temperature: 50°F to 90°F (10°C to 32°C)
  • Humidity: 20% to 80% non-condensing
  • Acoustic noise: 48 dBA operating

Performance

  • Print speed: 8 pages per minute
  • Resolution: 300 × 300 dpi
  • First page out: Approximately 35 seconds
  • Engine life: 300,000 pages rated
  • Duty cycle: 3,000 pages per month recommended

Power Requirements

  • Input voltage: 90-126V AC (auto-ranging)
  • Frequency: 50-60 Hz
  • Power consumption: 900W maximum
  • Current draw: 7.5A maximum
  • Heat output: 3,078 BTU per hour

System Architecture

Processor and Memory

The LaserWriter IISC used significantly reduced processing power compared to PostScript models:

Central Processing Unit:

  • CPU: Motorola MC68000
  • Clock speed: 7.45 MHz (slowest in LaserWriter line)
  • Data bus: 16-bit
  • Address bus: 24-bit

Memory Configuration:

  • ROM: 16 KB (minimal boot ROM only)
  • RAM: 1 MB total (fixed)
 * No separate workspace RAM
 * Frame buffer shared with system memory
  • RAM type: 120ns DRAM (4 × 256 KB chips)
  • RAM slots: 4 (fully populated)
  • Memory expansion: None possible

Controller Board Design

The IISC controller board was simplified compared to PostScript models:

  • Page description: QuickDraw host-based rendering
  • Font handling: No built-in fonts
  • Graphics processing: Bitmap reception only
  • SCSI controller: NCR 5380 or compatible
  • Interface logic: Minimal glue logic

QuickDraw Printing

Unlike PostScript LaserWriters, the IISC relied entirely on the host Macintosh:

Printing Process:

  1. Macintosh renders page using QuickDraw
  2. Bitmap transmitted via SCSI
  3. Printer receives and prints bitmap directly
  4. No processing or interpretation in printer

Font Requirements:

  • System 6: Adobe Type Manager (ATM) for scalable fonts
  • System 7: TrueType fonts supported natively
  • Bitmap fonts: Scaled by host, quality dependent on size

Canon LBP-SX Engine

The IISC used the improved Canon LBP-SX engine, shared with all LaserWriter II models:

Engine Specifications:

  • Technology: Laser xerography (electrophotographic)
  • Photosensitive drum: Organic photoconductor (OPC)
  • Laser type: Semiconductor laser diode
  • Developer system: Single-component toner
  • Fusing: Heat roller system
  • Paper path: Straight-through design

Improvements over LBP-CX:

  • Reduced size and weight
  • Improved paper handling
  • Better reliability
  • Quieter operation

Consumables

  • Toner cartridge: Apple M6002 or HP 92295A
  • Yield: Approximately 4,000 pages at 5% coverage
  • Drum life: Integrated with toner cartridge
  • OPC drum: Longer life than LBP-CX
  • Paper tray: 250-sheet capacity letter/legal cassette
  • Manual feed: Single-sheet bypass

Interfaces

SCSI Interface

The IISC was unique among LaserWriters in using SCSI as its primary interface:

SCSI Specifications:

  • Controller: NCR 5380 or compatible
  • SCSI version: SCSI-1 asynchronous
  • Transfer rate: Up to 5 MB/s theoretical (1-2 MB/s typical)
  • Connectors: Two DB-25 female ports
  • Termination: Internal termination when at chain end
  • Cable length: Maximum 6 meters total chain

SCSI Configuration:

  • SCSI ID: Set via DIP switches (0-6 usable)
  • ID 7: Reserved for self-test mode
  • Daisy-chaining: Supported via dual ports
  • Parity: Not implemented

SCSI ID DIP Switch Settings:

ID SW1 SW2 SW3 Function
0 OFF OFF OFF Normal operation
1 ON OFF OFF Normal operation
2 OFF ON OFF Normal operation
3 ON ON OFF Normal operation
4 OFF OFF ON Normal operation
5 ON OFF ON Normal operation
6 OFF ON ON Normal operation
7 ON ON ON Self-test mode

ADB Port

The IISC included an Apple Desktop Bus port that was never utilized:

ADB Specifications:

  • Connector: 4-pin mini-DIN
  • Purpose: Reserved for future expansion
  • Implementation: Non-functional in production units
  • Planned uses: Unknown (possibly status display or control panel)

Missing Interfaces

Unlike other LaserWriter II models, the IISC lacked:

  • LocalTalk/AppleTalk networking
  • RS-232 serial port
  • RS-422 serial port
  • Ethernet (never available on any LaserWriter II)

Paper Handling

Input Specifications

  • Standard cassette: 250 sheets
  • Manual feed: Single sheets
  • Paper sizes: Letter, Legal, A4, Executive
  • Paper weight: 16-28 lb bond (60-105 g/m²)
  • Media types: Plain paper, transparencies, envelopes, labels

Output Specifications

  • Output tray: 250-sheet capacity face-down
  • Stacking: Sequential page order
  • Duplex: Manual duplex only

Diagnostic Features

Self-Test Mode

Setting SCSI ID to 7 activated self-test mode:

  • Printer attempts to print test page on power-up
  • Test page shows configuration and status
  • No computer connection required
  • Useful for troubleshooting hardware issues

Status Indicators

Front panel LEDs indicated printer status:

  • Ready (green): Solid when ready to print
  • Paper (amber): Paper out or jam
  • Service (red): Service required
  • Two red lights blinking: Common failure mode

Error Conditions

Common error states indicated by LED patterns:

  • Continuous red blinking: Controller board failure
  • Alternating amber/red: Print engine problem
  • All lights on: Power supply issue
  • No lights: Fuse blown or power supply dead

Driver Software

Macintosh System Requirements

  • Minimum OS: System 6.0.3
  • Recommended: System 7.0 or later
  • RAM: 2 MB minimum, 4 MB recommended
  • SCSI: Built-in or expansion card

Driver Installation

The IISC required specific printer drivers:

  • LaserWriter IISC driver: Included with printer
  • Personal LaserWriter SC driver: Sometimes compatible
  • Chooser extension: Required for printer selection
  • Font support: ATM or TrueType required for quality output

Printing Process

  1. Select LaserWriter IISC in Chooser
  2. Application sends QuickDraw commands to driver
  3. Driver renders page to bitmap
  4. Bitmap compressed and sent via SCSI
  5. Printer receives and prints bitmap

Common Issues and Maintenance

Known Problems

Common IISC Failures
Component Symptoms Cause Repair
DC controller Two red lights blinking Capacitor failure Recap board
Logic board No communication Bad capacitors (3 total) Replace capacitors
SCSI termination Intermittent connection Termination issues Check SCSI chain
Power supply No power or cycling Capacitor failure Replace all electrolytics
Fuser assembly Poor toner adhesion Worn heating element Replace fuser
Scanner motor Horizontal lines Motor failure Replace motor assembly

Capacitor Issues

The IISC logic board contained only three electrolytic capacitors, but failure was common:

  • Symptoms: Two blinking red lights, no response
  • All three capacitors should be replaced preventively
  • Use 105°C rated replacements

SCSI Troubleshooting

Connection Issues:

  • Verify unique SCSI ID (0-6)
  • Check cable quality and length
  • Ensure proper termination
  • Test with printer as only SCSI device

Driver Problems:

  • Reinstall printer driver
  • Try Personal LaserWriter SC driver
  • Check SCSI chain for conflicts
  • Verify System software compatibility

Preventive Maintenance

Regular Service:

  • Monthly: Clean corona wires
  • 50,000 pages: General cleaning and inspection
  • 100,000 pages: Replace transfer corona
  • 200,000 pages: Replace fuser assembly
  • 300,000 pages: Major overhaul

Cleaning Procedures:

  • Use only toner-rated vacuum
  • Clean paper path with lint-free cloth
  • Wipe exterior with damp cloth
  • Avoid liquid near electronics

Upgrade Path

Controller Board Upgrades

The IISC could be upgraded to higher LaserWriter II models by replacing the controller board:

Available Upgrades:

  • IINT board: Added PostScript and LocalTalk
  • IINTX board: Added PostScript, LocalTalk, and SCSI font storage
  • IIf board: Added PostScript Level 2 and SCSI
  • IIg board: Added PostScript Level 2 and Ethernet

Upgrade Process:

  1. Remove IISC controller board
  2. Install replacement board
  3. Update printer drivers
  4. Configure for network if applicable

Cost Consideration: Upgrade boards were expensive, often costing more than a used printer

Service Information

DC Controller Settings

The DC controller board included service adjustments:

  • Print density: Potentiometer adjustment
  • Registration: Mechanical laser alignment
  • Service button: Initiates test page

Test Points

  • +5V DC digital logic
  • +24V DC motor supply
  • SCSI signal lines
  • High voltage (requires special probe)

Service Mode

  • Set SCSI ID to 7 for self-test
  • Hold service button on DC controller for test page
  • No other service modes available

Comparison with LaserWriter II Models

LaserWriter II Series Comparison
Feature IISC IINT IINTX IIf IIg
PostScript No Level 1 Level 1 Level 2 Level 2
Processor 68000 @ 7.45 MHz 68000 @ 11.5 MHz 68020 @ 16.67 MHz 68030 @ 25 MHz 68030 @ 25 MHz
RAM 1 MB fixed 2 MB min 2-12 MB 2-32 MB 5-32 MB
LocalTalk No Yes Yes Yes Yes
SCSI Yes (2 ports) No Yes (font storage) Yes Yes
Ethernet No No No No Yes
ADB Yes (unused) Yes (unused) Yes (unused) No No
Price (1988) $2,999 $4,599 $5,999 $3,599 (1991) $4,599 (1991)

Compatibility

System Requirements

  • System 6.0.3 minimum: Basic printing support
  • System 6.0.5 or later: Improved driver
  • System 7.0: TrueType font support
  • System 7.1: Best compatibility
  • System 7.5.x: Fully supported

Compatible Macintosh Models

Any Macintosh with SCSI port:

  • Macintosh Plus and later
  • Macintosh SE, SE/30
  • Macintosh II series
  • Macintosh LC series (with SCSI)
  • Macintosh Quadra series
  • PowerBook models with SCSI

Software Compatibility

  • Required QuickDraw-aware applications
  • No PostScript support
  • Limited graphics capabilities
  • Best with word processors and simple layouts

Service Manual

The LaserWriter II series service manual is available on the Apple Service Source page.

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