Macintosh IIsi: Difference between revisions
Verify against Apple's Macintosh IIsi Service Source (hosted, already cited at the foot of this page): maximum power is Apple's 100 W, not the '160 W Sony power supply' the body of the page claimed; RAM is 2 MB standard (1 MB soldered plus a SIMM) expandable to 17 MB; hard drive is 40 MB with an optional 80 MB, not 40/80/160; added Apple's replace-below-3.0 V battery threshold - the IIsi is 3.0 V, not the 2.8 V often applied to it from the IIcx/IIci - and the 68030's 256-byte caches and burst... |
Collapse duplicated <ref name=...> definition to one (a second definition of the same name renders as a red cite error) |
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* '''32-bit internal registers''' with 32-bit data path | * '''32-bit internal registers''' with 32-bit data path | ||
* '''24-bit or 32-bit addressing modes''' | * '''24-bit or 32-bit addressing modes''' | ||
* '''256-byte instruction and data caches''' on the 68030, and '''burst-mode RAM access''' — Apple's own wording<ref name="ssmacintoshiisi" /> | * '''256-byte instruction and data caches''' on the 68030, and '''burst-mode RAM access''' — Apple's own wording<ref name="ssmacintoshiisi">Apple Computer, ''Macintosh IIsi Service Source'' ([[Macintosh IIsi Service Source]], [[:File:Macintosh_iisi.pdf]]), Specifications chapter and Additional Procedures → Battery Verification.</ref> | ||
* '''No Level 2 cache''' | * '''No Level 2 cache''' | ||
| Line 123: | Line 123: | ||
== Power == | == Power == | ||
* '''Maximum power''': '''100 W''', not including the monitor — Apple's figure<ref name="ssmacintoshiisi" | * '''Maximum power''': '''100 W''', not including the monitor — Apple's figure<ref name="ssmacintoshiisi" /> | ||
* '''Input voltage''': 100–240 VAC, '''automatically configured''' | * '''Input voltage''': 100–240 VAC, '''automatically configured''' | ||
* '''Frequency''': 50–60 Hz, single phase | * '''Frequency''': 50–60 Hz, single phase | ||
| Line 239: | Line 239: | ||
'''100 W''' excluding the monitor, and the PRAM cell threshold as '''replace below 3.0 V'''. It also | '''100 W''' excluding the monitor, and the PRAM cell threshold as '''replace below 3.0 V'''. It also | ||
records that the '''68882 FPU is on the optional adapter card, not the logic board''' — a IIsi with | records that the '''68882 FPU is on the optional adapter card, not the logic board''' — a IIsi with | ||
no card has no FPU, which is a common misdiagnosis.<ref name="ssmacintoshiisi" | no card has no FPU, which is a common misdiagnosis.<ref name="ssmacintoshiisi" /> | ||
One figure in that volume is '''wrong as printed'''. The expansion slot budget appears as | One figure in that volume is '''wrong as printed'''. The expansion slot budget appears as | ||
Revision as of 12:14, 27 September 2026
 | |
| 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 | 2 MB standard (1 MB soldered + SIMM), expandable to 17 MB |
| Storage | Internal 40 MB SCSI hard drive; optional internal 80 MB |
| 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 Apple's entry-level professional Macintosh, with more expandability than the Macintosh LC which launched the same day.[2]
The IIsi was the first Macintosh with built-in audio recording, featuring an integrated microphone input.[3] The compact desktop case was unique to the IIsi and not used for any other Macintosh model.
Architecture and Processor
The Macintosh IIsi uses a Motorola MC68030 microprocessor running at 20 MHz.[4]
- 32-bit internal registers with 32-bit data path
- 24-bit or 32-bit addressing modes
- 256-byte instruction and data caches on the 68030, and burst-mode RAM access — Apple's own wording[5]
- No Level 2 cache
The system bus runs at 20 MHz. Apple underclocked the IIsi from 25 MHz to 20 MHz to avoid cannibalizing sales of the more expensive IIci. Many users modified ("chipped") their IIsi to run at 25 MHz or 28 MHz.[6]
Floating Point Unit
The Motorola 68882 FPU is optional and not included on the logic board. The FPU installs via the Apple NuBus Adapter card, which plugs into the Processor Direct Slot and converts it to a NuBus slot while providing the FPU socket.[7]
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, add this 1 MB to the SIMM capacity.[8]
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.[9]
Video
The Macintosh IIsi uses integrated video that shares main system RAM, reducing available RAM and impacting performance.[10]
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)
Video uses the slow 1 MB of soldered RAM first, making video performance slower than dedicated VRAM systems. Setting the disk cache to 768 KB or larger forces video operations to use the faster SIMM RAM instead.[11]
Audio
The Macintosh IIsi was the first Macintosh with built-in audio input.[12]
- 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 develops sound issues over time due to its modular construction. The internal speaker mounts on a daughterboard with spring contacts that connect to the logic board. Speaker vibrations cause fretting of the contact surfaces, resulting in intermittent audio dropouts. Cleaning the contacts with a pencil eraser fixes this.[13]
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. The slot runs at 20 MHz instead of 16 MHz, so some SE/30 cards may not work.[14]
The Apple IIsi NuBus Adapter converts 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.[15]
Power
- Maximum power: 100 W, not including the monitor — Apple's figure[5]
- Input voltage: 100–240 VAC, automatically configured
- Frequency: 50–60 Hz, single phase
A "160 W Sony power supply" was previously given here, and appears elsewhere on this wiki. Apple's published maximum power for the IIsi is 100 W.
- BTU per Hour: 547.2
- PRAM battery: 3.6 V ½AA lithium. Apple's instruction is replace below 3.0 V[5] — not 2.8 V, which is the IIcx/IIci figure and is often applied to this machine by mistake. Neutralise lithium leakage with bicarbonate of soda, not vinegar
- 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 not shared with any other Macintosh. The case uses clips and latches rather than screws, requiring no tools for disassembly.[16]
- 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
Common maintenance concerns include capacitor leakage, PRAM battery failure, and speaker contact corrosion.
For cleaning, battery maintenance, board inspection, and power supply procedures, see the Macintosh IIsi General Maintenance page.
PCB Schematics & Service Manual
The Macintosh IIsi has a logic board, power supply, and speaker daughterboard. Apple Service Source documentation provides troubleshooting and repair information.
Apple Service Manual
The complete Apple Service Source manual is at Macintosh IIsi Service Source. Additional manuals are in the Apple Service Source category.
Capacitor Replacement Guide
The Macintosh IIsi logic board and power supply contain surface-mount electrolytic capacitors prone to leakage after 30+ years. Leaking capacitors corrode PCB traces and cause intermittent operation.
Logic Board Capacitors:
- 2 × 220 µF 16V (axial electrolytic)
- 11 × 47 µF 16V (surface-mount tantalum)
For capacitor specifications and procedures, see the Macintosh IIsi Capacitor Replacement Guide.[17]
Troubleshooting
Common issues include startup failures, video problems, audio dropouts, and SCSI device issues. Many problems are caused by capacitor failure or PRAM battery leakage.
For diagnostics on power, video, Sad Mac errors, sound, and SCSI failures, see 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 | Apple: 2 MB standard, expandable to 17 MB[5] — 1 MB soldered plus four 30-pin SIMM slots |
| 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 | Apple: "One slot for either a NuBus or 030 direct slot card", with 15 W maximum available to it[5]. The printed current figures in that volume read "+12 V 175 A / −12 V 150 A", which must be 175 mA and 150 mA — see the note below |
| 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 |
Service documentation
Apple's own service manual is hosted here as Macintosh IIsi Service Source. It gives 2 MB of RAM expandable to 17 MB, 512K of ROM, 256 bytes of PRAM, a maximum power of 100 W excluding the monitor, and the PRAM cell threshold as replace below 3.0 V. It also records that the 68882 FPU is on the optional adapter card, not the logic board — a IIsi with no card has no FPU, which is a common misdiagnosis.[5]
One figure in that volume is wrong as printed. The expansion slot budget appears as "+5 V 2.0 A / +12 V 175 A / −12 V 150 A" against a stated 15 W maximum for the slot. 175 A at 12 V is 2.1 kW; the figures must be 175 mA and 150 mA, which is exactly what the Macintosh Quadra 840AV Service Source prints for the same NuBus budget (0.175 A and 0.15 A).[5]
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)
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Apple Computer, Macintosh IIsi Service Source (Macintosh IIsi Service Source, File:Macintosh_iisi.pdf), Specifications chapter and Additional Procedures → Battery Verification.
- ↑ 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)