Macintosh Quadra 605

The Quadra 605 is an entry level 68040 based Apple Macintosh personal computer codenamed "Aladdin" or "Primus" which was released on October 21, 1993 and discontinued on October 16, 1994. It was the lowest-model Quadra and one of few Macintoshes to not share a case with another machine, although the internal layout is shared with the Performa/LC 475 family.

Specifications

Central processing unit: 25Mhz MC68LC040, 32bit bus. 8 KB of on-chip L1 Cache is divided into 4 KB of Data and 4 KB of Instruction cache. There are no other caches, although an L2 cache is possible via an LC PDS card.
Random access memory: 4 MB on the motherboard, one 72 pin SIMM socket for 80ns or faster SIMMs. The official supported maximum RAM is 36MB in one 72 pin SIMM, but larger SIMMs do work. ^[1]

Video: Two VRAM slots can take either two 256 KB 80ns VRAM SIMMs, or two 512 KB 80ns VRAM SIMMs. Installing one 512k and one 256k VRAM SIMM makes a mess of the display. Resolutions & colours available with the two VRAM configurations are shown in the table below.

	512k	1024k
512x384	Thousands	Thousands
640x480	256	Thousands
640x870	16	256
832x624	256	Thousands
1024x768	16	256
1152x870	16	256

Audio
- Out - stereo 8 bit, 11kHz or 22kHz
- In - Line-level. The input socket is a stereo socket, and can input two channels of a stereo signal - however these are mixed and only accessible to the hardware as a combined mono 8 bit signal. An Apple PlainTalk Microphone provides line-level input by using a longer 4-contact plug which receives power from a 5v supply within the input jack. Other microphones only give a mic-level input, and don't work with the Quadra 605.

Recording is possible at 11k or 22k samples/second, with filters applied at 3.5Khz and 7kHz respectively while recording.

Floppy Drive: 1.4 MB SuperDrive, manual inject.
Battery: 605s take a lithium half-AA cell 3.6v battery. If the battery is drained, the video will NOT start up. To succesfully start up a 605 with a flat or missing battery, turn it on for a few seconds, then turn off then on quickly. This leaves enough charge somewhere in the system for video to start up.
Power supply: 30 Watts standard, but many 2nd hand machines come with replacement PSUs, either third party, Apple replacement or stripped from earlier LC models. Some of these go up to 45 Watts.
Weight: 8.8 lbs/4kgs standard
Dimensions: 2.9" High x 12.2" Wide x 15.3" Deep / 7.4cm High x 31cm Wide x 38.8cm Deep. A Quadra 605 can support a monitor up to 35lb/15.9Kg.

Expansion

The Quadra 605 contains one LC III style 68030-compatible LC PDS compatible slot. This is not a true LC Processor Direct Slot, but emulates the previous machine's 68030 slot. Due to the success of the LC PDS in earlier Macs and with many expansion options having already been manufactured Apple decided to keep the same slot type in these 68040 machines. While the 605s LC PDS is mostly 68030 compatible, expansion cards made specifically for 030 processors will not work, such as 68881 or 68882 FPUs.

The Quadra 605 also contains one 50 pin internal connector and one 25-pin DB25 external connector both on the same SCSI Bus. SCSI is provided by an NCR 53C96 controller, which can achieve up to 5mb/sec given a fast enough drive; one DIN-8 Printer port and one DIN-9 Modem port. Similar to the Printer port, but the extra pin supplies +5v power from the ADB power supply. Apple recommends no more than 100mA should be drawn from this pin.

The Quadra 605, like many other personal computers, includes one port for use with a keyboard/mouse or other low-speed low-power peripherals. Power can be used from the ADB port, but Apple recommends no more than 200mA total. There is also space for one Low profile 3.5" 50-pin SCSI device.

Some earlier models also contain a ROM SIMM socket, located just to the right of the VRAM. No SIMMs containing ROMs were made for this slot, and most boards only contain the solder pads indicating its position. The ROMs as used are 2 surface mount chips located directly behind the CPU.

Misc

Some Quadra 605s have a Cuda reset switch which is used to manually reset the PRAM, located towards the back of the motherboard just to the front of the audio out port and labelled S1. Others don't have this switch installed, instead just having 2 solder pads within a silkscreened square

The keyboard power-on key will not start up a Quadra 605 as there is no soft power-on. Only the power switch at the back will turn a Quadra 605 on or off. Pressing the power-on key while running is the same as selecting shut down in Finder, and once a 605 has completed its shutdown process it will ask you to manually turn it off.

Quadra 605s have no reset button or programmer's button, but keyboard key combinations can perform the same functions. To reset, hold down the Apple, Option and Power keys. For a programmer's button click, hold down just the Apple and Power keys.

Gestald IDs

Gestalt IDs on a Quadra 605 depends on two things. Jumper J18 (located just behind the Hard Drive) will identify the computer as a Quadra 605 if it is ON, and as a LC475/Performa 47x if it is OFF. Overclocking and underclocking the motherboard also changes the Gestalt ID. A list of Gestalt IDs (with speed as reported by Newer Technology's "Clockometer") are as follows

J18	Gestalt ID	Name	Speed
ON	93	20Mhz Quadra 605	19.93Mhz
ON	94	25Mhz Quadra 605	24.75Mhz
ON	95	33Mhz Quadra 605	32.89Mhz
OFF	86	20Mhz LC475	19.93Mhz
OFF	89	25Mhz LC475	24.75Mhz
OFF	90	33Mhz LC475	32.89Mhz

System software

The Quadra 605 is capable of running Mac OS versions 7.1, 7.1.1 (Pro), 7.5, 7.5.1, 7.5.3, 7.5.5, 7.6, 7.6.1, 8.0 and 8.1. Versions of System Software below 7.5 require the use of System Enabler 065. If a Q605 is running System 7.1, overclocking it from the standard 25Mhz to 33Mhz will change the gestalt ID, but the operating system will recognise the new ID. Underclocking to 20Mhz however will leave change the gestalt ID to one the system doesn't recognise as compatible, and the system won't boot. System 7.5+ isn't affected by this issue.

Footnotes

^ LowEndMac states that up to 128MB may be used, with some limits on RAM type. Quadra 605s work with all single-banked SIMMs (Note that single-banked is a logic-level simm trait, not a physical one - single banked does NOT necessarily mean single sided - single-banked SIMMs may be either single or double sided) Physical limits of the RAM might apply if the side of the SIMM facing the CPU has thick chips mounted on it or the CPU has a heatsink (nonstandard) fitted. In that case the clips on the SIMM socket won't close around it automatically, but it should be possible to push them manually enough to hold the SIMM in place. Curiously, the DJMEMC memory controller used in the 605s predecessors, Quadra/Centris 610 and Quadra/Centris 650 will only recognise SIMMs up to 32 MB, while the newer MEMCjr used in the 605 recognises the larger sizes.

External links

[1] LowEndMac states that up to 128MB may be used, with some limits on RAM type. Quadra 605s work with all single-banked SIMMs (Note that single-banked is a logic-level simm trait, not a physical one - single banked does NOT necessarily mean single sided - single-banked SIMMs may be either single or double sided) Physical limits of the RAM might apply if the side of the SIMM facing the CPU has thick chips mounted on it or the CPU has a heatsink (nonstandard) fitted. In that case the clips on the SIMM socket won't close around it automatically, but it should be possible to push them manually enough to hold the SIMM in place. Curiously, the DJMEMC memory controller used in the 605s predecessors, Quadra/Centris 610 and Quadra/Centris 650 will only recognise SIMMs up to 32 MB, while the newer MEMCjr used in the 605 recognises the larger sizes.

[1]