Apple LaserWriter II 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

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.

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:

Macintosh renders page using QuickDraw
Bitmap transmitted via SCSI
Printer receives and prints bitmap directly
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

Print Engine

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

Select LaserWriter IISC in Chooser
Application sends QuickDraw commands to driver
Driver renders page to bitmap
Bitmap compressed and sent via SCSI
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:

Remove IISC controller board
Install replacement board
Update printer drivers
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.

Related Pages