Editing Macintosh Quadra 650

{{Infobox computer
| name         = Macintosh Quadra 650
| image        = [[File:Quadra_650_Front.jpg]]
| caption      = Macintosh Quadra 650
| manufacturer = Apple Computer, Inc.
| type         = Personal Computer
| release date = October 21, 1993
| discontinued = September 12, 1994
| price        = US$2,780–$3,250
| cpu          = Motorola 68040 @ 33 MHz
| memory       = 8 MB RAM (expandable to 136 MB)
| storage      = 230 or 500 MB SCSI HDD, optional 2X CD-ROM
| display      = Up to 1152×870 (with VRAM expansion)
| sound        = 8-bit stereo sound
| dimensions   = 6" H × 13" W × 16.5" D (15.2 × 33 × 41.9 cm)
| weight       = 25 lbs (11.3 kg)
| os           = System 7.1 – Mac OS 8.1
| predecessor  = [[Macintosh Centris 650]]
| successor    = [[Power Macintosh 7100]]
| codename     = 
| model        = M2118
}}
The '''Macintosh Quadra 650''' is a personal computer designed, manufactured, and sold by Apple Computer from October 1993 to September 1994.<ref>{{cite web |url=https://everymac.com/systems/apple/mac_quadra/specs/mac_quadra_650.html |title=Macintosh Quadra 650 Specs |publisher=EveryMac.com |access-date=2026-02-10}}</ref> It replaced the [[Macintosh Centris 650]], featuring an upgraded 33 MHz 68040 processor with integrated FPU.<ref>{{cite web |url=https://lowendmac.com/1993/quadra-650/ |title=Quadra 650 |publisher=Low End Mac |access-date=2026-02-10}}</ref>

Apple renamed the Centris line to Quadra in October 1993 to reduce product line confusion. The Quadra 650 uses the same logic board and [[Macintosh IIvx|IIvx]] tower case design as the Centris 650, with the processor upgraded from 25 MHz to 33 MHz.

== Model Variants ==

The Quadra 650 was sold in several configurations:

* ''M2107LL/A:'' 68040 @ 33 MHz, 8 MB RAM, 512 KB VRAM, 230 MB HDD (no CD-ROM)
* ''M2016LL/A:'' 68040 @ 33 MHz, 8 MB RAM, 1 MB VRAM, 230 MB HDD, 2X CD-ROM
* ''M2104LL/A:'' 68040 @ 33 MHz, 8 MB RAM, 1 MB VRAM, 500 MB HDD, 2X CD-ROM

All Quadra 650 models include the full 68040 with integrated FPU, unlike the entry-level Centris 650 which used the 68LC040.

== Architecture and Processor ==

The Quadra 650 uses the Motorola 68040 processor running at 33 MHz. The clock input runs at 66 MHz, but the processor is not clock-doubled, operating at 33 MHz.<ref>{{cite web |url=https://everymac.com/systems/apple/mac_quadra/specs/mac_quadra_650.html |title=Macintosh Quadra 650 Specs |publisher=EveryMac.com |access-date=2026-02-10}}</ref> Third-party processor upgrades and PowerPC upgrade cards were available via the PDS slot.

=== Processor Specifications ===
<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:70%; text-align:center;"
|-
! Component !! Specification
|-
| CPU || Motorola 68040 @ 33 MHz
|-
| Data Bus || 32-bit
|-
| Address Bus || 32-bit
|-
| L1 Cache || 8 KB
|-
| FPU || Integrated
|-
| System Bus || 33 MHz
|-
| Addressing || 24-bit or 32-bit
|}

=== Upgrade Options ===

* Sonnet Presto PPC 100 MHz PowerPC 601
* Daystar PowerPro 601 (50 MHz with 1 MB L2 cache)
* Various clock accelerators (up to 44 MHz)

== Memory and Storage ==

=== RAM Configuration ===

The Quadra 650 has either 4 MB or 8 MB of RAM soldered to the logic board, with four 72-pin SIMM slots for expansion.

* ''Minimum RAM:'' 4 or 8 MB (soldered)
* ''Maximum RAM:'' 132 MB (4 MB onboard) or 136 MB (8 MB onboard)
* ''SIMM Type:'' 72-pin, 80 ns or faster
* ''Supported Sizes:'' 4 MB, 8 MB, 16 MB, 32 MB

RAM can be interleaved for improved performance by installing matching pairs of SIMMs.

=== Video RAM ===

Onboard video supports 512 KB or 1 MB of VRAM via two 80 ns VRAM SIMM slots.

{| class="wikitable" style="width:70%"
|-
! Resolution !! 512 KB VRAM !! 1 MB VRAM
|-
| 512×384 || 16-bit || 16-bit
|-
| 640×480 || 8-bit || 16-bit
|-
| 800×600 || 8-bit || 16-bit
|-
| 832×624 || 8-bit || 16-bit
|-
| 1024×768 || 4-bit || 8-bit
|-
| 1152×870 || 4-bit || 8-bit
|}

Additional displays can be supported via NuBus video cards.

=== Storage Systems ===

* ''Internal Hard Drive:'' SCSI, 230 MB or 500 MB configurations
* ''Floppy Drive:'' 1.44 MB SuperDrive (manual inject)
* ''CD-ROM:'' Optional internal 2X AppleCD 300i (5.25" bay)

== Input/Output and Expansion ==

=== Port Configuration ===

{| class="wikitable" style="width:70%"
|-
! Port !! Quantity !! Notes
|-
| ADB || 2 || Keyboard and mouse
|-
| Serial (Mini DIN-8) || 2 || Modem and Printer, 57.6 kbps max
|-
| External SCSI (DB-25) || 1 || Up to 6 external devices
|-
| AAUI-15 Ethernet || 1 || Built-in
|-
| Video (DB-15) || 1 || VGA via adapter
|-
| Sound In || 1 || 3.5mm stereo
|-
| Sound Out || 1 || 3.5mm stereo
|}

=== Expansion Slots ===

* ''NuBus 90 Slots:'' 3
* ''Processor Direct Slot (PDS):'' 1 (040 PDS)
* ''5.25" External Bay:'' 1 (available if CD-ROM not installed)

The floppy drive sled can also be used for a hard drive if the floppy is not needed.

== General Maintenance ==

For detailed maintenance practices including cleaning, PRAM battery management, connector corrosion prevention, and voltage adjustments, refer to the dedicated [[Macintosh Centris 650 General Maintenance]] page.

''Note:'' The Centris/Quadra 650 logic board uses tantalum capacitors rather than electrolytic capacitors, so the logic board does not require recapping. However, the power supply unit contains electrolytic capacitors that may need replacement.

== PCB Schematics & Service Manual ==

The Macintosh Quadra 650 shares its logic board design with the Centris 650. The Apple Service Source manual covers both models.

=== Apple Service Manual ===

<pdf width="800" height="500">File:quadra.centris_650.pdf</pdf>

All Apple Service Manuals can be found on the [[:Category:Apple Service Source|Apple Service Source]] page.

== Capacitor Replacement Guide ==

Detailed capacitor replacement guidelines can be found on the [[Macintosh Centris 650 Capacitor Replacement Guide]] page.

''Important:'' The logic board uses tantalum capacitors and does not require recapping. Only the power supply contains electrolytic capacitors.

== Retrobrite ==

To address plastic yellowing on the case, detailed instructions can be found on the [[Retrobrite]] page.

== Troubleshooting ==

A comprehensive troubleshooting guide addressing no power, video issues, and common problems is available on the [[Macintosh Centris 650 Troubleshooting]] page.

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

=== System Architecture at a Glance ===
{| class="wikitable styled-table" style="width:90%; text-align:center;"
! Sub-system !! Specification (Macintosh Quadra 650, October 1993)
|-
| ''CPU'' || Motorola 68040 @ 33 MHz
|-
| ''Bus width'' || 32-bit data • 32-bit address
|-
| ''ROM'' || 1 MB
|-
| ''RAM'' || 8 MB standard (expandable to 136 MB)
|-
| ''Video'' || Up to 1152×870 with 1 MB VRAM
|-
| ''Sound'' || 8-bit stereo, 22 kHz
|-
| ''Disks'' || SCSI HDD, 1.44 MB floppy, optional CD-ROM
|-
| ''Expansion'' || 3 NuBus 90, 1 PDS
|-
| ''Power'' || 100–240V AC, 50–60 Hz, 230W max
|-
| ''Gestalt ID'' || 36
|}

=== Performance ===
{| class="wikitable styled-table" style="width:70%; text-align:center;"
|-
! Benchmark !! Score
|-
| Relative to SE || 14.6
|-
| Speedometer 3 || 21.9
|-
| Speedometer 4 || 1.19
|-
| MIPS || 29
|}

== Related Models ==

* ''[[Macintosh Centris 650]]'' – Predecessor with 25 MHz processor
* ''[[Macintosh Centris 610]]'' – Smaller desktop variant (became Quadra 610)
* ''[[Macintosh Quadra 610]]'' – Pizza-box form factor
* ''[[Macintosh IIvx]]'' – Uses same case design
* ''[[Power Macintosh 7100]]'' – Successor, uses same case

== Service Documentation ==

The official Apple Service Source documentation for this model:

<pdf width="800" height="500">File:Quadra.centris_650.pdf</pdf>

== See Also ==

* [[Macintosh Centris 650 General Maintenance]]
* [[Macintosh Centris 650 Troubleshooting]]
* [[Macintosh Centris 650 Capacitor Replacement Guide]]

== References ==
<references />

[[Category:Apple Vintage Computers]]
[[Category:Macintosh Quadra]]