Macintosh IIsi
 | |
| Macintosh IIsi | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Desktop Personal Computer |
| Released | October 15, 1990 |
| Discontinued | March 15, 1993 |
| Intro price | US$2,999 – $3,770 |
| CPU | Motorola 68030 @ 20 MHz |
| Memory | 1 MB RAM soldered (expandable to 17 MB) |
| Storage | 40 MB, 80 MB, or 160 MB SCSI hard drive |
| Display | Integrated video (640×480 @ 8-bit color) |
| Sound | 8-bit stereo output, 8-bit mono input |
| Dimensions | 4.0" H × 12.4" W × 14.9" D (10.2 × 31.5 × 37.8 cm) |
| Weight | 10 lbs (4.5 kg) |
| OS / Firmware | System 6.0.7 – Mac OS 7.6.1 |
| Predecessor | Macintosh IIci |
| Successor | Macintosh Centris 610 |
| Codename | Erickson, Raffica, Ray Ban, Spin, Oceanic |
| Model no. | M0360 |
The Macintosh IIsi is a desktop personal computer designed, manufactured, and sold by Apple Computer, Inc. from October 1990 to March 1993.[1] Introduced as a lower-cost alternative to the Macintosh IIci, the IIsi was positioned as Apple's entry-level professional Macintosh, offering more expandability and performance than the Macintosh LC which was introduced simultaneously.[2]
The IIsi was notable for being the first Macintosh with built-in audio recording capabilities, featuring an integrated microphone input.[3] The compact desktop case design was unique to the IIsi and was not used for any other Macintosh model.
Architecture and Processor
The Macintosh IIsi is powered by a Motorola MC68030 microprocessor running at 20 MHz.[4] The processor features:
- 32-bit internal registers with 32-bit data path
- 24-bit or 32-bit addressing modes
- 0.5 KB Level 1 cache (on-chip)
- No Level 2 cache
The system bus operates at 20 MHz. Apple intentionally underclocked the IIsi's components from 25 MHz to 20 MHz to avoid competing with the more expensive IIci. Many users subsequently modified ("chipped") their IIsi to run at 25 MHz or even 28 MHz for improved performance.[5]
Floating Point Unit
The Motorola 68882 FPU is an optional upgrade, not included on the logic board. The FPU must be installed via the Apple NuBus Adapter card, which plugs into the Processor Direct Slot and converts it to a NuBus slot while simultaneously providing the FPU socket.[6]
Memory
RAM Configuration
- Soldered RAM: 1 MB on logic board
- SIMM Slots: 4 × 30-pin SIMM slots
- SIMM Speed: 100 ns minimum
- Maximum RAM: 17 MB (Apple official), 65 MB (with unofficial 16 MB SIMMs)
- SIMM Installation: Must be installed in matched groups of four identical SIMMs
- Supported SIMM Sizes: 256 KB, 512 KB, 1 MB, 2 MB, 4 MB (8 MB and 16 MB SIMMs work but are not officially supported)
The IIsi's 1 MB of soldered RAM cannot be removed or disabled. When calculating total RAM, this 1 MB must be added to the SIMM capacity.[7]
ROM
- ROM Size: 512 KB
- ROM Type: Usually soldered to the logic board
- ROM SIMM Slot: Present on some units; may contain a ROM SIMM instead of soldered ROMs
- ROM ID: $067C
Some IIsi units shipped with ROMs on a removable SIMM rather than soldered chips. The IIsi ROM is reportedly compatible with the Macintosh SE/30 and may provide 32-bit clean operation when installed.[8]
Video
The Macintosh IIsi uses an integrated video system that shares main system RAM for video memory, which reduces available RAM and impacts performance.[9]
Video Specifications
- Video Output: DB-15 connector
- Video RAM: 64 KB – 320 KB (shared from system RAM, depending on resolution)
- Maximum Resolution: 640 × 480 pixels
- Color Depth: 8-bit (256 colors) at 640 × 480
- Portrait Monitor Support: 640 × 870 at 4-bit (16 grays)
Because video shares system memory, and specifically uses the slow 1 MB of soldered RAM first, video performance is notably slower than dedicated VRAM systems. A workaround involves setting the disk cache to 768 KB or larger, forcing video operations to use the faster SIMM RAM instead.[10]
Audio
The Macintosh IIsi was the first Macintosh to include built-in audio input capabilities.[11]
- Audio Output: 8-bit stereo, 22 kHz
- Audio Input: 8-bit mono, omnidirectional microphone input
- Output Jack: 3.5 mm stereo headphone jack
- Input Jack: 3.5 mm microphone input
- Internal Speaker: Mono speaker on daughterboard
The IIsi is known to develop sound issues over time due to its modular construction. The internal speaker is mounted on a daughterboard with spring contacts that connect to the logic board. Speaker vibrations can cause fretting of the contact surfaces, resulting in intermittent audio dropouts. This can be remedied by cleaning the contacts with a pencil eraser.[12]
Storage
Hard Drive
- Interface: SCSI (DB-25 external connector)
- Standard Capacities: 40 MB, 80 MB, or 160 MB
- Internal Bay: One 3.5" SCSI hard drive bay
Floppy Drive
- Drive Type: Apple SuperDrive (1.44 MB)
- Floppy Capacity: 1.44 MB (HD) and 800 KB (DD)
- Injection Type: Auto-inject
- External Connector: DB-19 floppy port
Input/Output and Expansion
Ports
- ADB Ports: 1 (Apple Desktop Bus for keyboard and mouse)
- Serial Ports: 2 × Mini DIN-8 RS-422 (Printer and Modem)
- SCSI Port: DB-25 connector
- Floppy Port: DB-19 connector
- Video Port: DB-15 connector
- Audio Output: 3.5 mm stereo jack
- Audio Input: 3.5 mm microphone jack
Expansion Slot
The IIsi has a single Processor Direct Slot (PDS) compatible with Macintosh SE/30 expansion cards (though running at 20 MHz instead of 16 MHz, some SE/30 cards may not work).[13]
An optional Apple IIsi NuBus Adapter card can convert the PDS slot to accept standard 7-inch NuBus cards. This adapter also includes a socket for the optional 68882 FPU. With a slim hard drive, 12-inch NuBus cards may also fit.[14]
Power
- Power Supply: 160W internal
- Input Voltage: 100V – 240V AC
- Frequency: 50 – 60 Hz
- Maximum Wattage: 160W
- BTU per Hour: 547.2
- PRAM Battery: 3.6V lithium half-AA
- Soft Power: Yes (power controlled via ADB keyboard)
- Pass-Through: Yes (power outlet on back for monitor)
Case Design
The IIsi uses a unique compact desktop case that was not used for any other Macintosh model. The case was designed for easy assembly and manufacturing, using clips and latches rather than screws, such that no tools are required for disassembly.[15]
- Dimensions: 4.0" H × 12.4" W × 14.9" D (10.2 × 31.5 × 37.8 cm)
- Weight: 10 lbs (4.5 kg)
General Maintenance
Proper maintenance is essential to extending the lifespan and ensuring the reliable operation of your Macintosh IIsi. Common maintenance concerns include capacitor leakage, PRAM battery failure, and speaker contact corrosion.
For detailed cleaning, battery maintenance, board inspection, and power supply procedures, refer to the Macintosh IIsi General Maintenance page.
PCB Schematics & Service Manual
The Macintosh IIsi consists of a logic board, power supply, and speaker daughterboard. Apple Service Source documentation provides detailed troubleshooting and repair information.
Apple Service Manual
The complete Apple Service Source manual is available at Macintosh IIsi Service Source. Additional Apple Service Manuals can be found in the Apple Service Source category.
Capacitor Replacement Guide
The Macintosh IIsi logic board and power supply contain surface-mount electrolytic capacitors that are prone to leakage after 30+ years of age. Leaking capacitors can cause corrosion damage to PCB traces and intermittent operation.
Logic Board Capacitors:
- 2 × 220 µF 16V (axial electrolytic)
- 11 × 47 µF 16V (surface-mount tantalum)
Detailed capacitor replacement specifications and procedures can be found on the Macintosh IIsi Capacitor Replacement Guide page.[16]
Troubleshooting
Common issues with the Macintosh IIsi include startup failures, video problems, audio dropouts, and SCSI device issues. Many problems are related to capacitor failure or PRAM battery leakage.
A comprehensive troubleshooting guide addressing no power, video issues, Sad Mac errors, sound problems, and SCSI drive failures is available on the Macintosh IIsi Troubleshooting page.
Technical Specifications
System Overview
| Sub-system | Specification (Macintosh IIsi, October 1990) |
|---|---|
| CPU | Motorola 68030 @ 20 MHz |
| FPU | Optional Motorola 68882 (via NuBus adapter) |
| Bus Width | 32-bit data • 24-bit or 32-bit addressing |
| ROM | 512 KB |
| RAM | 1 MB soldered + 4 × 30-pin SIMM slots (17 MB max official) |
| L1 Cache | 0.5 KB (on-chip) |
| L2 Cache | None |
| Video | Integrated, 640 × 480 @ 8-bit (shares system RAM) |
| Sound | 8-bit stereo output • 8-bit mono input |
| Storage | 40/80/160 MB SCSI HDD • 1.44 MB SuperDrive |
| Expansion | 1 × SE/30 PDS (convertible to NuBus with adapter) |
| Ports | ADB • 2 × Serial • SCSI • Floppy • Video • Audio I/O |
Model Configurations
| Order Number | RAM | Hard Drive | Price (1990) |
|---|---|---|---|
| M0363LL/A | 2 MB | 40 MB | US$2,999 |
| M0364LL/A | 5 MB | 80 MB | US$3,769 |
| M0364LL/B | 5 MB | 80 MB | — |
| M0491LL/B | 3 MB | 40 MB | — |
| M0954LL/A | 5 MB | 160 MB | — |
Identification
| Identifier | Value |
|---|---|
| Apple Model Number | M0360 |
| Gestalt ID | 18 |
| ROM ID | $067C |
See Also
References
- ↑ Macintosh IIsi: Technical Specifications, Apple Inc.—link(accessed 2026-02-09)
- ↑ Macintosh IIsi Specs, EveryMac.com—link(accessed 2026-02-09)
- ↑ Mac IIsi, Low End Mac—link(accessed 2026-02-09)
- ↑ Macintosh IIsi, Wikipedia—link(accessed 2026-02-09)
- ↑ Mac IIsi, Low End Mac—link(accessed 2026-02-09)
- ↑ Macintosh IIsi Specs, EveryMac.com—link(accessed 2026-02-09)
- ↑ Macintosh IIsi: Technical Specifications, Apple Inc.—link(accessed 2026-02-09)
- ↑ Mac IIsi, Low End Mac—link(accessed 2026-02-09)
- ↑ Macintosh IIsi, Wikipedia—link(accessed 2026-02-09)
- ↑ Macintosh IIsi, Wikipedia—link(accessed 2026-02-09)
- ↑ Mac IIsi, Low End Mac—link(accessed 2026-02-09)
- ↑ Macintosh IIsi, Wikipedia—link(accessed 2026-02-09)
- ↑ Mac IIsi, Low End Mac—link(accessed 2026-02-09)
- ↑ Macintosh IIsi Specs, EveryMac.com—link(accessed 2026-02-09)
- ↑ Macintosh IIsi, Wikipedia—link(accessed 2026-02-09)
- ↑ Caps! -- Macintosh IIsi, 68kMLA—link(accessed 2026-02-09)