Editing Macintosh IIx

{{Infobox computer
| name         = Macintosh IIx
| image        = [[File:Macintosh IIx.jpg|250px]]
| caption      = Macintosh IIx
| manufacturer = Apple Computer, Inc.
| type         = Personal computer
| release date = September 19, 1988
| discontinued = October 15, 1990
| price        = US$7,769 – $9,369 (with 40 MB HD)
| cpu          = Motorola 68030 @ 16 MHz
| memory       = 1 MB or 4 MB standard, expandable to 128 MB
| storage      = Optional 40 MB or 80 MB SCSI hard drive
| display      = None built-in (requires NuBus graphics card)
| sound        = 8-bit stereo, 22.254 kHz sampling
| dimensions   = 5.5" H × 18.5" W × 14.4" D (140 × 470 × 365 mm)
| weight       = 24 lbs (10.9 kg)
| os           = System 6.0.2 – Mac OS 8.1 (with Mode32)
| predecessor  = [[Macintosh II]]
| successor    = [[Macintosh IIfx]]
| codename     = Spock, Stratos
| model        = M5810 (1 MB), M5820 (4 MB)
}}

The '''Macintosh IIx''' was introduced on September 19, 1988, as an incremental upgrade to the [[Macintosh II]]. The IIx replaced the 16 MHz Motorola 68020 processor with a 68030 running at the same clock speed, added the 68882 FPU as standard, and introduced the 1.44 MB SuperDrive (FDHD) floppy drive. The IIx maintained the same six-slot NuBus architecture and modular case design as its predecessor while adding integrated PMMU support and 256 bytes each of instruction and data cache.

== Development & Market Position ==

Apple developed the IIx under the codenames "Spock" and "Stratos" as a straightforward evolution of the Macintosh II architecture. The "x" suffix indicated the presence of the 68030 CPU, a naming convention Apple used across multiple models including the [[Macintosh IIcx]] and [[Macintosh IIvx]].

Released at $7,769 for a base configuration or $9,369 with a 40 MB hard drive, the IIx targeted professional users requiring expandability and performance. The machine competed directly with workstations from Sun Microsystems, Silicon Graphics, and Hewlett-Packard. Apple increased the Macintosh II's price by approximately 20% just before the IIx introduction, positioning the new model as a modest upgrade cost.

== Model Configurations ==

The IIx was available in several standard configurations:

=== Base Models ===
* '''Macintosh IIx 1/0''' – 1 MB RAM, dual 1.44 MB floppy drives, no hard drive
* '''Macintosh IIx 4/0''' – 4 MB RAM, dual 1.44 MB floppy drives, no hard drive
* '''Macintosh IIx 1/40''' – 1 MB RAM, one 1.44 MB floppy, 40 MB hard drive
* '''Macintosh IIx 4/40''' – 4 MB RAM, one 1.44 MB floppy, 40 MB hard drive
* '''Macintosh IIx 4/80''' – 4 MB RAM, one 1.44 MB floppy, 80 MB hard drive

All configurations required at least one NuBus graphics card for video output, as the IIx had no built-in video capability.

== General Maintenance ==
Power-on circuit repair, battery replacement, capacitor inspection, and cleaning procedures are documented in [[Macintosh IIx General Maintenance]].

== PCB Architecture & Service Documentation ==

The IIx consists of a large logic board with integrated I/O and expansion, plus a separate power supply unit:

=== Logic Board ===
The IIx logic board features:
* '''Motorola 68030''' processor at 16 MHz with integrated MMU
* '''Motorola 68882''' FPU at 16 MHz
* '''ROM SIMM slot''' containing required 256 KB ROM
* '''Eight 30-pin SIMM slots''' in two banks of four
* '''Six NuBus slots''' for expansion cards
* '''SWIM chip''' for SuperDrive support

=== Power Supply ===
The power supply provides:
* +5V, +12V, -12V regulated outputs
* 230W maximum output
* Soft power control via ADB
* Pass-through AC outlet

=== Apple Service Manual ===
<pdf width="800" height="500">File:macintosh_ii.iix.iifx.pdf</pdf>

Service documentation is available on the [[:Category:Apple Service Source|Apple Service Source]] page.

== Capacitor Replacement Guide ==
Surface-mount electrolytic capacitors on the IIx logic board are prone to leakage after 30+ years. Replacement procedures and specifications are documented on the [[Macintosh IIx Capacitor Replacement Guide]] page.

== Troubleshooting ==
Power-on failures, chimes of death, NuBus issues, and memory problems are covered in the [[Macintosh IIx Troubleshooting]] guide.

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

=== System Architecture ===
{| class="wikitable styled-table" style="width:90%; text-align:center;"
! Sub-system !! Specification (Macintosh IIx, September 1988)
|-
| '''CPU''' || Motorola 68030 @ 16 MHz • Integrated PMMU • 256 bytes I-cache + 256 bytes D-cache
|-
| '''Bus width''' || 32-bit data • 32-bit address (4 GB theoretical, 128 MB actual limit)
|-
| '''ROM''' || 256 KB ROM SIMM • "Dirty" ROMs require Mode32 for >8 MB RAM
|-
| '''RAM''' || 1-128 MB via 30-pin SIMMs • Two banks of four slots • 120ns or faster
|-
| '''Video''' || None built-in • Requires NuBus graphics card
|-
| '''Sound''' || Apple Sound Chip (ASC) • 4-voice stereo • 22.254 kHz sampling
|-
| '''Storage''' || 1.44 MB SuperDrive standard • Optional 40/80 MB SCSI hard drive
|-
| '''I/O Ports''' || ADB × 2 • Mini-DIN-8 serial × 2 • DB-25 SCSI • DB-19 floppy
|-
| '''Expansion''' || Six NuBus slots • 10 MHz bus speed • 10-40 MB/s bandwidth
|}

=== Memory Configuration ===

The IIx uses eight 30-pin SIMM slots arranged in two banks of four. Both banks must be populated with identical SIMMs within each bank.

{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''Memory Configurations'''
! Bank A !! Bank B !! Total RAM !! Notes
|-
| 4 × 256 KB || Empty || 1 MB || Minimum configuration
|-
| 4 × 256 KB || 4 × 256 KB || 2 MB || 
|-
| 4 × 1 MB || Empty || 4 MB || 
|-
| 4 × 1 MB || 4 × 1 MB || 8 MB || Maximum without Mode32
|-
| 4 × 4 MB PAL || Empty || 16 MB || Requires Mode32
|-
| 4 × 4 MB PAL || 4 × 1 MB || 20 MB || Requires Mode32
|-
| 4 × 4 MB PAL || 4 × 4 MB PAL || 32 MB || Requires Mode32
|-
| 4 × 16 MB PAL || 4 × 16 MB PAL || 128 MB || Maximum, requires Mode32
|}

'''Important notes:'''
* 4 MB and 16 MB SIMMs must be PAL (Presence Detect) type
* Mode32 or 32-bit System Enabler required for >8 MB configurations
* Bank A must be populated before Bank B can be used

=== ROM Specifications ===

The IIx requires a ROM SIMM in the dedicated ROM slot. The ROM is "32-bit dirty," containing 24-bit addressing code that limits RAM access to 8 MB without software patches.

{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''ROM Details'''
! Version !! Size !! Features !! Limitations
|-
| IIx ROM || 256 KB || SWIM support, 68030 optimizations || 32-bit dirty, 8 MB limit without Mode32
|-
| IIfx ROM || 512 KB || 32-bit clean alternative || Not officially supported but functional
|}

=== NuBus Architecture ===

The six NuBus slots provide the primary expansion capability:

{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''NuBus Specifications'''
! Parameter !! Specification
|-
| Bus speed || 10 MHz
|-
| Data width || 32-bit
|-
| Address space || 256 MB per slot
|-
| Bandwidth || 10-40 MB/s (theoretical)
|-
| Slot numbering || 9, A, B, C, D, E (hexadecimal)
|-
| Power per slot || +5V @ 2A, +12V @ 0.3A, -12V @ 0.3A
|}

'''Common NuBus cards:'''
* '''Graphics cards''' – Apple 8•24, Radius DirectColor/GX
* '''Accelerators''' – DayStar Digital PowerCache, Radius Rocket
* '''Network cards''' – Ethernet, Token Ring adapters
* '''Video capture''' – Media Time, VideoSpigot
* '''Additional I/O''' – Serial/parallel expansion cards

=== SuperDrive (FDHD) System ===

The IIx was the first Macintosh II series computer with built-in SuperDrive support:

==== Technical Specifications ====
* '''Controller:''' SWIM (Super Wozniak Integrated Machine) chip
* '''Capacity:''' 1.44 MB (high density), 800 KB (double density), 400 KB (single density)
* '''Encoding:''' MFM for 1.44 MB, GCR for 400/800 KB
* '''Compatibility:''' Mac, ProDOS, MS-DOS formats (with software)
* '''Transfer rate:''' Up to 62.5 KB/s

==== Drive Support Matrix ====
{| class="wikitable styled-table" style="width:80%; text-align:center;"
! Drive Type !! Internal Support !! External Support
|-
| 400 KB || Read only || Read only
|-
| 800 KB || Full support || Full support
|-
| 1.44 MB || Full support || Full support
|-
| MS-DOS 720 KB || With Apple File Exchange || With Apple File Exchange
|-
| MS-DOS 1.44 MB || With Apple File Exchange || With Apple File Exchange
|}

=== SCSI Subsystem ===

The IIx uses the NCR 5380 SCSI controller providing:
* '''SCSI-1 interface''' (5 MB/s maximum)
* '''Seven device support''' (ID 0-6, Mac is ID 7)
* '''DB-25 external connector'''
* '''50-pin internal connector'''
* '''Asynchronous transfers only'''

Real-world SCSI performance typically achieves 1.4 MB/s with appropriate drives and proper termination.

=== Audio System ===

The Apple Sound Chip (ASC) provides enhanced audio capabilities:
* '''Four-voice wavetable synthesis'''
* '''Stereo output''' via dual 8-bit DACs
* '''22.254 kHz standard sampling rate'''
* '''11.127 kHz and 7.418 kHz alternate rates'''
* '''512-byte FIFO buffer per channel'''

=== Power Specifications ===
* '''Input:''' 100-132V or 198-264V AC, 47-63 Hz (switch selectable)
* '''Maximum power:''' 230W
* '''BTU/hr:''' 786.6
* '''Power distribution:'''
** +5V @ 14.0A
** +12V @ 1.8A 
** -12V @ 0.25A
** -5V @ 0.1A
=== Power-On Circuit ===

The IIx features a complex power-on circuit that requires functioning batteries:

{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''Power-On Circuit Components'''
! Component !! Function !! Common Failure Mode
|-
| Dual 3.6V batteries || Provide 7V for power-on circuit || Dead batteries prevent power-on
|-
| UB1, UB2 transistors || Switch power supply control || Capacitor leakage damages transistors
|-
| C5, C6 capacitors || Filter power-on circuit || Leakage breaks nearby traces
|-
| R3, R18 resistors || Current limiting || Corrosion from capacitor leakage
|}

Without functioning batteries or with damaged power-on components, the IIx cannot start via the rear power button or ADB power key.

== 32-bit Addressing & Mode32 ==

The IIx ships with "32-bit dirty" ROMs containing residual 24-bit code. This limits usable RAM to 8 MB regardless of physical installation. To access more than 8 MB:

=== Software Solutions ===
* '''Mode32 1.2''' – For System 7.0/7.1
* '''Mode32 7.5''' – For System 7.5.x
* '''32-bit System Enabler''' – Apple's solution (less stable than Mode32)
* '''System 7.6''' – Requires 32-bit clean ROMs (not compatible)

=== Installation Process ===
# Install physical RAM beyond 8 MB
# Install Mode32 in System Folder
# Open Memory control panel
# Check "32-bit Addressing"
# Restart

== Known Issues & Solutions ==

=== Power-On Failures ===
* '''No response to power button''' – Dead batteries or damaged power-on circuit
* '''Powers on via ADB only''' – UB1/UB2 transistor failure
* '''Clicking/ticking sound''' – Power supply protection, check for shorts

=== Memory Issues ===
* '''Only recognizes 8 MB''' – Install Mode32 and enable 32-bit addressing
* '''Chimes of death''' – Reseat SIMMs, verify matched sets
* '''Random crashes''' – Replace PAL SIMMs with correct type

=== Video Problems ===
* '''No video output''' – Verify NuBus card seated properly
* '''Grayscale only''' – Check monitor sense pins on video cable
* '''Distorted display''' – Clean NuBus contacts with contact cleaner

=== SCSI Issues ===
* '''Devices not recognized''' – Check termination and cable quality
* '''Slow performance''' – Verify proper termination at chain ends
* '''System hangs at startup''' – Remove all SCSI devices, test individually

== Upgrade Paths ==

=== Processor Upgrades ===
* '''DayStar Digital PowerCache''' – 33/40/50 MHz 68030 accelerators
* '''Radius Rocket''' – 68040-based NuBus coprocessor cards

=== Video Upgrades ===
* '''Apple 8•24 GC''' – Accelerated 24-bit graphics
* '''Radius DirectColor/GX''' – High-performance graphics
* '''SuperMac Thunder/24''' – 24-bit accelerated video

=== Storage Upgrades ===
* '''Larger SCSI drives''' – Up to 2 GB supported natively
* '''SCSI-2 cards''' – DayStar Digital SCSI PowerCard for faster transfers

== Historical Context ==

The IIx served as Apple's high-end workstation from September 1988 until the [[Macintosh IIfx]] introduction in March 1990. Notable uses included:
* Industrial Light & Magic for "The Abyss" image processing
* Publishing industry for early desktop publishing
* Scientific computing with FPU-intensive applications
* CAD/CAM workstation applications

Production ceased October 15, 1990, after approximately 80,000 units sold. Support and spare parts were discontinued August 31, 1998.

== Maintenance Resources ==
* [[Macintosh IIx General Maintenance]] – Cleaning and battery service
* [[Macintosh IIx Capacitor Replacement Guide]] – Capacitor specifications
* [[Macintosh IIx Troubleshooting]] – Diagnostic procedures
* [[NuBus Card Guide]] – Expansion card information
* [[SCSI Configuration Guide]] – Termination and setup

== Related Pages ==
* [[Macintosh II]] – Direct predecessor
* [[Macintosh IIfx]] – High-performance successor  
* [[Macintosh IIcx]] – Compact three-slot variant
* [[Macintosh IIci]] – Built-in video successor
* [[Mode32]] – 32-bit addressing enabler

[[Category:Apple Vintage Computers]]
{{Navbox-AppleVintage}}