Using the same case as the Quadra 800, the 840av incorporates the same AV circuitry as the Centris 660av. Running a 40 MHz CPU, this was Apple’s fastest 68040-based computer ever.

The 840av also 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.

One popular use for the AV Quadras was adding text and graphics to videos.

This model’s only real drawback is the terrible case.

Tidbit: Hold down Cmd-Opt-T-V during startup to force this Mac to use a TV as a monitor.

• Got a Quadra? Join the Vintage Macs email list.

Details

• introduced 1993.07.29 at $4,700; discontinued 1994.07.18
• requires System 7.1 (with System Enabler 088 v1.0) or later; highest version supported is Mac OS 8.1.
• CPU: 40 MHz 68040
• DSP: 67 MHz AT&T 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 has 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: 1 MB VRAM, expandable to 2 MB using four 256 KB 80ns VRAM SIMMs
  • 512 x 384, 640 x 400 @ 24-bit
  • 640 x 480, 800 x 600, 832 x 624: 16-bit @ 1 MB, 24-bit @ 2 MB
  • 1024 x 768, 1152 x 870: 8-bit @ 1 MB, 16-bit @ 2 MB
• L2 cache: optional
• ADB: 2 ports for keyboard and mouse
• serial: 2 DIN-8 RS-422 ports on back of computer
• SCSI: DB-25 connector on back of computer
• Hard drive: 230 MB, 500 MB, or 1 GB
• Ethernet: built in AUI-15 (AAUI) port, requires adapter
• video I/O: S-video in and out; composite video in and out; supports input and output in NTSC, PAL, and SECAM formats
• audio: 16-bit stereo input and output ports use mini phone-jack connectors, sample rate to 48 KHz
• Hard drive: 230, 500, or 1000 MB
• CD-ROM: 2x
• NuBus: 3 NuBus 90 slots
• PDS slot: none
• size (HxWxD): 14.25″ x 7.75″ x 16″ (360 x 196 x 396 mm)
• Weight: 24 lbs. (11.3 kg)
• power supply: 200 W maximum output, 100-240 VAC input @ 50-60 Hz
• PRAM battery: 3.6V half-AA
• Gestalt ID: 78
• addressing: 32-bit
• upgrade path: Power Mac 8100, 8500

Accelerators & Upgrades

• Output Enablers 46-48 MHz clock accelerator
• MicroMac Speedy variable speed oscillator (to 46 MHz)
• Power Mac 8100

Online Resources

• Low End Mac’s GeoPort Guide, Tommy Yune, 2018.03.21
• Overclocking the Quadra AV Models
• Know Your Mac’s Upgrade Options, Phil Herlihy, The Usefulness Equation, 2008.08.26. Any Mac can be upgraded, but it’s a question of what can be upgraded – RAM, hard drive, video, CPU – and how far it can be upgraded.
• The Compressed Air Keyboard Repair, Charles W Moore, Miscellaneous Ramblings, 2008.07.24. If your keyboard isn’t working as well as it once did, blasting under the keys with compressed air may be the cure.
• Tales of old Mac data retrieval, Adam Rosen, Adam’s Apple, 2008.06.13. Getting apps and documents off 400K floppies, old disk images, and a Mac running System 5.
• A Vintage Mac Network Can Be as Useful as a Modern One, Carl Nygren, My Turn, 2008.04.08. Old Macs can exchange data and share an Internet connection very nicely using Apple’s old LocalTalk networking.
• Vintage Mac Networking and File Exchange, Adam Rosen, Adam’s Apple, 2007.12.19. How to network vintage Macs with modern Macs and tips on exchanging files using floppies, Zip disks, and other media.
• Vintage Mac Video and Monitor Mania, Adam Rosen, Adam’s Apple, 2007.12.17. Vintage Macs and monitors didn’t use VGA connectors. Tips on making modern monitors work with old Macs.
• Getting Inside Vintage Macs and Swapping Out Bad Parts, Adam Rosen, Adam’s Apple, 2007.12.14. When an old Mac dies, the best source of parts is usually another dead Mac with different failed parts.
• Solving Mac Startup Problems, Adam Rosen, Adam’s Apple, 2007.12.12. When your old Mac won’t boot, the most likely culprits are a dead PRAM battery or a failed (or failing) hard drive.
• The 25 most important Macs (part 2), Dan Knight, Mac Musings, 2009.02.17. The 25 most significant Macs in the first 25 years of the platform, continued.
• Golden Apples: The 25 best Macs to date, Michelle Klein-Häss, Geek Speak, 2009.01.27. The best Macs from 1984 through 2009, including a couple that aren’t technically Macs.
• Why You Should Partition Your Mac’s Hard Drive, Dan Knight, Mac Musings, 2008.12.11. “At the very least, it makes sense to have a second partition with a bootable version of the Mac OS, so if you have problems with your work partition, you can boot from the ’emergency’ partition to run Disk Utility and other diagnostics.”
• Better and Safer Surfing with Internet Explorer and the Classic Mac OS, Max Wallgren, Mac Daniel, 2007.11.06. Tips on which browsers work best with different Mac OS versions plus extra software to clean cookies and caches, detect viruses, handle downloads, etc.
• Hacking Mac OS 7.6.1 so many Mac OS 8 apps will run, Max Wallgren, Mac Daniel, 2007.10.30. With a little ResEdit work and a second copy of your System Folder, you can run a lot of OS 8 apps with Mac OS 7.6.1.
• Simple Macs for Simple Tasks, Tommy Thomas, Welcome to Macintosh, 2007.10.19. Long live 680×0 Macs and the classic Mac OS. For simple tasks such as writing, they can provide a great, low distraction environment.
• Interchangeabilty and Compatibility of Apple 1.4 MB Floppy SuperDrives, Sonic Purity, Mac Daniel, 2007.09.26. Apple used two kinds of high-density floppy drives on Macs, auto-inject and manual inject. Can they be swapped?
• Apple’s AAUI ethernet connector, Dan Knight, Online Tech Journal, 2007.09.04. From 1991 through 1995, Apple used a proprietary ethernet connection. Why they created AAUI and where to find adapters.
• Connecting a LaserWriter to ethernet and the TiBook that wouldn’t boot, Dan Knight, Low End Mac Mailbag, 2007.08.23. The importance of an AAUI ethernet adapter, the cost of PowerBook PRAM batteries, and booting old Macs from SCSI drives.
• Apple’s first phone a fake, build your own Macintel, Internet options for G3 Macs, and more, Dan Knight, Low End Mac Mailbag, 2007.07.23. Also a Cube that won’t boot, moving data from an old Mac, useful resource for PowerBook 1400 owners, reformatting a Quadra’s hard drive, finding an AirPort power supply, and more.
• Mac System 7.5.5 Can Do Anything Mac OS 7.6.1 Can, Tyler Sable, Classic Restorations, 2007.06.04. Yes, it is possible to run Internet Explorer 5.1.7 and SoundJam with System 7.5.5. You just need to have all the updates – and make one modification for SoundJam.
• Appearance Manager Allows Internet Explorer 5.1.7 to Work with Mac OS 7.6.1, Max Wallgren, Mac Daniel, 2007.05.23. Want a fairly modern browser with an old, fast operating system? Mac OS 7.6.1 plus the Appearance Manager and Internet Explorer may be just what you want.
• Importance of G3 support in 10.5, clever USB/FireWire solution, upgrade options, and more, Dan Knight, Low End Mac Mailbag, 2007.05.01. Also the loss of the PowerBook brand, upgrading to an Intel iMac, Korg and the Mac, Quadra boot problems, and the value of a Mac Classic.
• Format Any Drive for Older Macs with Patched Apple Tools, Tyler Sable, Classic Restorations, 2007.04.25. Apple HD SC Setup and Drive Setup only work with Apple branded hard drives – until you apply the patches linked to this article.
• Making floppies and CDs for older Macs using modern Macs, Windows, and Linux PCs, Tyler Sable, Classic Restorations, 2007.03.15. Older Macs use HFS floppies and CDs. Here are the free resources you’ll need to write floppies or CDs for vintage Macs using your modern computer.
• System 7 Today, advocates of Apple’s ‘orphan’ Mac OS 7.6.1, Tommy Thomas, Welcome to Macintosh, 2006.10.26. Why Mac OS 7.6.1 is far better for 68040 and PowerPC Macs than System 7.5.x.
• Mac OS 8 and 8.1: Maximum Size, Maximum Convenience, Tyler Sable, Classic Restorations, 2006.09.11. Mac OS 8 and 8.1 add some useful new features and tools, and it can even be practical on 68030-based Macs.
• Moving files from your new Mac to your vintage Mac, Paul Brierley, The ‘Book Beat, 2006.06.13. Old Macs use floppies; new ones don’t. Old Macs use AppleTalk; Tiger doesn’t support it. New Macs can burn CDs, but old CD drives can’t always read CD-R. So how do you move the files?
• Setting up a 68040-based Mac media center, Nathan Thompson, Embracing Obsolescence, 2006.05.12. Yes, that old ‘040-based Quadra or Performa just might make a decent media center for listening to MP3s and watching videos.
• Damaged Goods: A Quadra 840av brought back from the brink, Tyler Sable, Classic Restorations, 2006.04.05. The Quadra 840av motherboard somehow survived a tragic shipping fiasco, but where would it live and what would it be used for?
• System 7.6.1 is perfect for many older Macs, John Martorana, That Old Mac Magic, 2006.03.24. Want the best speed from your old Mac? System 7.6.1 can give you that with a fairly small memory footprint – also helpful on older Macs.
• System 7.5 and Mac OS 7.6: The beginning and end of an era, Tyler Sable, Classic Restorations, 2006.02.15. System 7.5 and Mac OS 7.6 introduced many new features and greater modernity while staying within reach of most early Macintosh models.
• Web browser tips for the classic Mac OS, Nathan Thompson, Embracing Obsolescence, 2006.01.03. Tips on getting the most out of WaMCom, Mozilla, Internet Explorer, iCab, Opera, and WannaBe using the classic Mac OS.
• The video revolution, Mark Benson, 68kMac.com, 2005.10.05. Apple’s revolutionary Centris 660av and Quadra 840av – and how to use them today.
• Getting to the Power Mac 8500 motherboard, Dan Knight, Low End Mac Mailbag, 2003.05.28. “It’s been a few years since I’ve been inside one of these, but I can pretty much walk you through it from memory.”
• Quadra AVs and some cool things you can do with them, Adam Robert Guha, Apple Archive, 2001.08.10. Thanks to digital signal processors, the Quadra AVs remain useful video machines.
• 660av/840av Video Input Specifics, James Wang.
• Quadra AV FAQ, James Wang
• Options for ‘040 Macs, Adam Robert Guha, Apple Archive, 2000.06.05. Advice about operating systems, upgrades, what Quadra to choose, and more.
• Games for ‘040 Macs, Low End Mac Gaming, Brian Rumsey, 2000.02.25. This week Brian looks at games to play on 68040-based Macs.
• Gaming on ‘040 Macs, Brian Rumsey, Low End Mac Gaming, 2000.02.16. Those old 68040-class Macs still have game.
• Six Year Old Mac to the Rescue, Scott Atkinson, Mac Musings, 1999.11.12. The Quadra 660av has what it takes to capture stills from video for a television Web site.
• Easter Egg, MacKiDo
• Vintage Macs, the email list for 680×0-based Macs
• Mac AV list, an email list for 660av and 840av users
• Macintosh AV Series: Video Features and Subsystems, Apple Knowledge Base Archive
• Memory Upgrade Guide
• For more information on Mac serial ports, read Macintosh Serial Throughput
• Macintosh Quadra 840av Technical Specifications, Apple Knowledge Base Archive

Cautions

• Apple Computer considers this computer obsolete as of 2001.07.16 in the United States and 2001.07.23 in Canada. Service parts and documentation are no longer available from Apple.
• 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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