Quadra 840av

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Overview

Using the same case as the Quadra 800, the 840av incorporated the same AV circuitry as the Centris 660av. Running a 40 MHz CPU, this was Apple's fastest 68040-based computer ever. The 840av runs a faster version of the AT&T DSP chip, one clocked at 66 MHz v. 55 MHz in the 660av. This and the 660av were the only Quadras to use the GeoPort high speed serial port.

Details

introduced July 1993 at $4,700; discontinued July 1994
requires System 7.1 or later
CPU: 40 MHz 68040
DSP: 67 MHz 3210
performance: 16.5, relative to SE; 12.13, MacBench 2.0 CPU; 1.58, Speedometer 4; 35 MIPS
ROM: 2 MB
RAM: 4 MB, expandable to 128 MB using 60ns 72-pin SIMMs; motherboard had 4 SIMM slots which can be filled individually but should ideally be filled in interleaved pairs; can use 4 MB, 8 MB, 16 MB, and 32 MB SIMMs
video: 512 KB VRAM; supports 512x384, 640x400, 640x480, 640x870, 800x600, 832x624, 1024x768, and 1152x870 resolutions
L2 cache: optional
ADB ports for keyboard and mouse
DIN-8 serial ports on back of computer
DB-25 SCSI connector on back of computer
three NuBus 90 slots
one PDS slot, aligned with first NuBus slot
upgrade path: Power Mac 8100

Accelerators & Upgrades

Output Enablers 46-48 MHz clock accelerator
Griffin Mac-celerator (variable speed to 48 MHz, incl. fan)
MicroMac Speedy variable speed oscillator (to 46 MHz), available from Outpost.com
Power Mac 8100

Online Resources

Six Year Old Mac to the Rescue, Scott Atkinson, Mac Musings, 11/12/99. The Quadra 660av has what it takes to capture stills from video for a television web site.
72-pin SIMM memory pricing, RAMseeker
Easter Egg, MacKiDo
Quadra AV FAQ, James Wang
Quadlist, the email list for 68040-based Macs
Mac AV list, an email list for 660av and 840av users
Video I/O options, Apple TIL 16770
Memory Upgrade Guide
AppleFacts Online for Quadra 840av.
For more information on Mac serial ports, read Macintosh Serial Throughput on the Macintosh Online Technical Journal.

Cautions

The Startup Disk control panel in System 7.5-7.5.3 is incompatible with Quadra AVs. System 7.5.5 fixes this.
Quadra AVs do not support 24-bit addressing.
You must have a "fat" system installed to use a PowerPC upgrade.
Note that the 660av and 840av don't do video mirroring, so if you're doing output to TV or VCR, your computer monitor will be blank.

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