Macintosh Quadra 605

Macintosh Quadra 605

Macintosh Quadra 605 (photo: Danamania, CC BY-SA 2.5, via Wikimedia Commons)
Specifications
Manufacturer	Apple Computer, Inc.
Type	Desktop personal computer
Released	October 21, 1993
Discontinued	October 17, 1994
Intro price	US$900 (4 MB/80 MB), US$1,300 (8 MB/160 MB)
CPU	Motorola 68LC040 at 25 MHz (socketed; no FPU)
Memory	4 MB on the logic board, one 72-pin SIMM socket, 36 MB maximum (80 ns)
Storage	80 or 160 MB SCSI hard disk; 1.4 MB SuperDrive
Display	External monitor; 512 KB VRAM, expandable to 1 MB
Sound	Mono input, stereo output, 8-bit at 11 or 22 kHz
ROM	1 MB
Expansion	One LC-style expansion slot (96- or 114-pin cards)
Power	26 W maximum, 100-240 V AC
Dimensions	7.7 × 31.0 × 38.2 cm (3.0 × 12.2 × 15.0 in)
Weight	4.0 kg (8.8 lb)
OS / Firmware	System 7.1 to Mac OS 8.1
Model no.	M1476

The Macintosh Quadra 605 is a low-profile desktop Macintosh introduced by Apple on October 21, 1993 and discontinued on October 17, 1994. Apple's developer note describes it and the Macintosh LC 475 as Apple's lowest-priced models with 68040-family processors, mechanically similar to the Macintosh LC III and electrically similar to the Macintosh Centris 650. The same hardware was sold as the LC 475 and as the Performa 475 and Performa 476, which differed in the hard disk supplied (160 MB and 230 MB).

Identification

Quadra 605 identifiers

Item	Value
Model number	M1476
Order number	M1821LL/A (4 MB RAM, 80 MB hard disk)
Gestalt machine type	94 ($5E); the LC 475 is 89 ($59)

EveryMac gives the Quadra 605's Gestalt ID as 89, which Apple's developer note assigns to the LC 475.

Processor and architecture

The Quadra 605 uses a Motorola 68LC040 at 25 MHz: a 68040 without the floating-point unit. The processor sits in a socket, so it can be replaced with a full 68040 to add the FPU; an expansion card cannot add one. Low End Mac notes that a 33 MHz 68040 fitted to the 605 still runs at 25 MHz.

The machine has two internal buses. The system bus runs at the processor clock; the I/O bus runs at 16 MHz and is buffered by Apple's PrimeTime IC, which gives 68030-style byte steering and dynamic bus sizing for older I/O software. The five custom ICs are MEMCjr (memory controller and frame buffer), PrimeTime (I/O buffer, SWIM II floppy controller, both VIAs), DFAC II (sound input), Cuda (ADB and power control) and Antelope (video CLUT and DAC). The SCSI controller is a 53C96.

Apple's service replacement logic board is the same part for the LC 475 and the Quadra 605; a Quadra 605 board has a jumper fitted on pins J18, which Apple's technician moves from the old board to the new one.

There is no programmer's switch. The NMI is Command-Power On and a reset is Control-Command-Power On, each held for at least one second.

Memory

The logic board has 4 MB of RAM and one 72-pin SIMM socket. Apple's configurations run from 4 MB to 36 MB using 1, 2, 4, 8, 16 or 32 MB SIMMs; access time must be 80 ns or less, and the SIMM contacts must be tin. Apple's service manual lists 4 MB or 8 MB as shipped. EveryMac reports that third parties have run the machine with a 128 MB SIMM, for 132 MB.

Apple's developer note gives 1 MB of ROM soldered to the logic board; the Service Source's memory page says "512K expandable to 1 MB" for the LC III, LC 475 and Quadra 605.

Video

All video RAM is on two 68-pin VRAM SIMMs; there is none on the board. Both sockets must be filled with SIMMs of the same size, 256 KB each (512 KB total) or 512 KB each (1 MB); the system does not recognise more than 1 MB.

Maximum pixel depth (bits per pixel), from Apple's developer note Table 1-2

Monitor	Pixels	512 KB VRAM	1 MB VRAM
12-inch colour	512 × 384	16	16
12-inch monochrome	640 × 480	8	8
14-inch colour, VGA or NTSC	640 × 480	8	16
15-inch portrait	640 × 870	4	8
16-inch colour	832 × 624	8	16
19-inch colour	1024 × 768	4	8
21-inch colour or monochrome	1152 × 870	4	8

Storage, sound and ports

• Hard disk: 80 or 160 MB internal SCSI in Apple's developer note; the Service Source lists 160 or 230 MB for the LC 475 and Quadra 605 together.
• Floppy: one 1.4 MB Apple SuperDrive, auto-inject or manual-insert.
• Ports: two serial ports (the modem port is a 9-pin mini-DIN carrying +5 V on pin 9, with 500 mA shared with ADB), SCSI (DB-25), one ADB port, DB-15 video, sound in and sound out.
• Sound: 8-bit, 11 or 22 kHz; mono input, stereo output. The LC and LC II microphone does not work; the input needs the line-level Apple PlainTalk microphone.

Expansion

The single internal slot takes 96-pin cards designed for the LC II and 114-pin cards designed for the LC III. It is not a processor-direct slot: it does not connect to the 68LC040, runs at 16 MHz and does not support 68040 bus transfers. Accelerators, 68882 FPU cards and cache cards made for 68020 or 68030 machines do not work in it. The card fits parallel to the logic board and reaches a knock-out opening in the back of the case.

Power available to an expansion card (4 W total maximum)

Rail	Maximum current
+5 V	800 mA
−5 V	20 mA
+12 V	200 mA

Source: developer note Table 3-3.

Apple's own Macintosh Processor Upgrade fits the 605: a PowerPC 601 card with a socket for the original 68LC040 and a 256K cache card, needing at least 8 MB of RAM and System 7.5. Low End Mac gives its clock as 50 MHz.

Power supply and battery

Apple rates the Quadra 605 at 26 W maximum, 100-240 V AC automatically configured, 50-60 Hz. The same page gives 50 W for the LC and LC II and 30 W for the LC III. The exploded view for the family lists power supply 661-1733 and lithium battery 742-0011. Apple's battery check is to replace the battery if it reads below 3.0 V; EveryMac gives the type as 3.6 V lithium.

Service documentation

• Macintosh LC Series/ Quadra 605 Service Source: Apple's module-level service manual for the LC, LC II, LC III, LC 475 and Quadra 605.
• Macintosh LC 475 and Quadra 605 Developer Note: specifications, pin assignments, custom ICs and the expansion-card design guide.
• Macintosh Processor Upgrade Service Source

General maintenance, capacitors and troubleshooting

• Macintosh Quadra 605 General Maintenance
• Macintosh Quadra 605 Capacitor Replacement Guide
• Macintosh Quadra 605 Troubleshooting

Gallery

• 
  Inside a Quadra 605: hard disk, speaker, fan, floppy drive, power supply and logic board (photo: Danamania, CC BY-SA 2.5)
• 
  Quadra 605 rear ports, with an Ethernet card's RJ-45 socket in the expansion opening (photo: Danamania, CC BY-SA 2.5)

Related pages

• Macintosh LC 475
• Macintosh Performa 475
• Macintosh Performa 476
• Macintosh LC III
• Macintosh Centris 650