Editing Macintosh LC III

{{Infobox computer
| name         = Macintosh LC III
| image        = [[File:Macintosh LC III.jpg|250px]]
| caption      = Macintosh LC III
| manufacturer = Apple Computer, Inc.
| type         = Personal Computer
| release_date = February 10, 1993
| discontinued = February 14, 1994
| price        = US$1,349
| cpu          = Motorola 68030 @ 25 MHz
| memory       = 4 MB RAM (expandable to 36 MB)
| storage      = 80 MB SCSI HDD, 1.44 MB SuperDrive
| display      = 640×480 8-bit (512K VRAM) or 16-bit (768K VRAM)
| sound        = 8-bit stereo input/output
| dimensions   = 2.9" H × 12.2" W × 15.3" D
| weight       = 8.8 lbs (4.0 kg)
| os           = System 7.1 – System 7.6.1
| predecessor  = [[Macintosh LC II]]
| successor    = [[Macintosh LC III+]]
| codename     = Vail, Elsie III
| model        = M1254
}}
The '''Macintosh LC III''' is a personal computer released by Apple on February 10, 1993.<ref>{{cite web |url=https://www.apple-history.com/lc_iii |title=Macintosh LC III |publisher=Apple History |access-date=2026-02-09}}</ref> The LC III addressed the main performance limitation of earlier LC models by implementing a full 32-bit data bus, providing a substantial performance improvement over the [[Macintosh LC II]].<ref>{{cite web |url=https://everymac.com/systems/apple/mac_lc/specs/mac_lc_iii.html |title=Apple Macintosh LC III Specs |publisher=EveryMac.com |access-date=2026-02-09}}</ref>

== Model Variants ==

The LC III was sold as the Performa 450 in consumer markets with bundled software.

== Architecture and Processor ==

The LC III uses a Motorola 68030 processor running at 25 MHz with a '''full 32-bit data bus'''—a significant improvement over the 16-bit bus of the LC and LC II. This change substantially improved memory performance and overall system responsiveness.<ref>{{cite web |url=https://lowendmac.com/1993/macintosh-lc-iii/ |title=Macintosh LC III |publisher=Low End Mac |access-date=2026-02-09}}</ref>

The LC III includes a socket for an optional Motorola 68882 FPU (Floating Point Unit), the first LC to offer FPU support.

The Gestalt ID for the Macintosh LC III is 27.

== Memory and Storage ==

=== RAM Configuration ===

The LC III shipped with 4 MB of RAM standard, expandable to 36 MB. A significant change from earlier LCs: the LC III uses a '''single 72-pin SIMM slot''' instead of 30-pin SIMM pairs.

{| class="wikitable"
|+ '''RAM Configurations'''
|-
! Configuration !! SIMM Required
|-
| 4 MB || 4 MB 72-pin SIMM (or 4 MB onboard)
|-
| 8 MB || 4 MB onboard + 4 MB SIMM
|-
| 12 MB || 4 MB onboard + 8 MB SIMM
|-
| 20 MB || 4 MB onboard + 16 MB SIMM
|-
| 36 MB || 4 MB onboard + 32 MB SIMM
|}

=== Video RAM ===

The LC III includes 512 KB of VRAM onboard, expandable to 768 KB with a 256 KB VRAM SIMM:

* 512 KB VRAM: 640×480 at 8-bit (256 colors)
* 768 KB VRAM: 640×480 at 16-bit (thousands of colors)

=== ROM ===

The LC III contains 1 MB of ROM, double that of earlier LC models.

=== Storage Systems ===

Standard storage included:
* 80 MB internal SCSI hard drive
* 1.44 MB SuperDrive

== Input/Output and Expansion ==

=== Port Configuration ===

* 1× Apple Desktop Bus (ADB) port
* 1× External SCSI (DB-25)
* 1× Audio input (3.5mm stereo minijack)
* 1× Audio output (3.5mm stereo minijack)
* 2× Serial ports (Mini DIN-8)
* 1× Video output (DA-15)

=== Expansion ===

The LC III features a single LC Processor Direct Slot (LC PDS) and an FPU socket (PGA) for the 68882 coprocessor.

== General Maintenance ==

For detailed maintenance practices including cleaning, PRAM battery management, and connector care, refer to the dedicated [[Macintosh LC III General Maintenance]] page.

== Troubleshooting ==

A comprehensive troubleshooting guide addressing common issues with the Macintosh LC III is available on the [[Macintosh LC III Troubleshooting]] page.

== Capacitor Replacement ==

The Macintosh LC III logic board contains surface-mount electrolytic capacitors that commonly fail due to age. Detailed replacement guidelines can be found on the [[Macintosh LC III Capacitor Replacement Guide]] page.

'''Important:''' The LC III has a known factory defect where capacitor C22 was installed with reversed polarity due to a silkscreen error. See the capacitor replacement guide for details.

== Technical Details ==

{| class="wikitable" style="width:70%; text-align:center;"
|+ '''Macintosh LC III Technical Specifications'''
|-
! Component !! Specification
|-
| '''CPU''' || Motorola 68030 @ 25 MHz
|-
| '''FPU''' || Optional 68882 (socket provided)
|-
| '''PMMU''' || Integrated in 68030
|-
| '''Data Bus''' || 32-bit
|-
| '''System Bus''' || 25 MHz
|-
| '''ROM''' || 1 MB
|-
| '''RAM''' || 4 MB (max 36 MB)
|-
| '''VRAM''' || 512 KB (max 768 KB)
|}

== References ==
<references />

[[Category:Apple Vintage Computers]]