20th Anniversary Mac

The Twentieth Anniversary Macintosh (or TAM) was a radical change from existing computers. The slim unit (just 2.5″ deep) uses the same kind of LCD screen usually found in laptops. Bose Acoustimass stereo speakers surround it, along with a large subwoofer in the base power unit, for really exceptional sound.

20th Anniversary Mac

20th Anniversary Mac

20th Anniversary Mac

20th Anniversary Mac

The 12.1″ active-matrix screen and leather-bound keyboard are based on parts shared with the PowerBook 3400c. It doesn’t come with a numeric keypad or mouse, but does include a trackpad. The TAM uses a 2.5″ laptop hard drive, the first desktop Mac to do so (the second was the first Mac mini, introduced in 2005).

The logic board is based on the “Gazelle” architecture shared by the Power Mac 5500 and 6500. According to MacSpeedZone, upgrading the 256 KB level 2 (L2) cache to 512 KB boosts performance by 15%; going to 1 MB improves it by 27%. Some power users have used the L2 cache slot to upgrade to a G3 processor.

20th Anniversary Mac

20th Anniversary Mac

Apple built 12,000 TAMs, making it a bit less rare than the Macintosh TV, which had 10,000 units made. 399 of those TAMs were retained by Apple for use as service parts. Like the Mac TV, the TAM had a built-in television tuner, but it also included an FM radio. Then again, the TAM was very expensive, while Mac TV was aimed at consumers; finding either in good working order today will fetch a hefty premium.

Though the TAM wasn’t a success, it was one of the first high-profile projects of renowned designer Jonathan Ive at Apple. Within five years Apple introduced the second desktop Mac with an LCD monitor, the 15″ iMac G4. But it wasn’t until August 2004 that the first thinner, lighter iMac G5 arrived in 17″ and 20″ editions, the true successor to the TAM’s design — a design that iMacs continue to use to this day.

20th Anniversary Mac in "Batman and Robin"

20th Anniversary Mac in “Batman & Robin”

A prototype TAM, code-named “Spartacus”, had a small role in 1997’s Batman & Robin. A production version was seen being used by Jerry Seinfeld on his TV show. An aged and weathered version recently made an appearance within a museum in Peter Jackson’s production of Mortal Engines.

The TAM’s internal 2 GB drive originally shipped with Mac OS 7.6.1, which only supports standard HFS formatting. Steve Wozniak warned that using a disk partition larger than 4 GB would cause the system to hang, although other users have experienced mixed results. Mac OS 8.1 introduced HFS Plus (also known as Mac OS Extended), which allowed drives to be formatted up to 136 GB (the limit allowed by the TAM’s ATA-5 IDE controller).


  • Code names: Pomona, Spartacus
  • Introduced 1997.03.20 at $7,499, discontinued 1998.03.14
  • Part no.: M3459 (base unit)
  • Gestalt ID: 512
  • Upgrade path: L2 cache slot upgrades

Mac OS

  • Requires Mac OS 7.6.1 (with System Enabler 704) through 9.1 (Mac OS 8.0 also requires a special version)

Core System

  • CPU: 250 MHz PPC 603e with built-in floating-point unit
  • Level 2 cache: 256 KB, expandable to 1 MB
  • Bus: 50 MHz
  • ROM: 4 MB
  • RAM: 32 MB (expandable to 128 MB, accepts two 168-pin 5V 60ns or faster EDO or FPM DIMMs)
  • Power supply: 90-130/180-264 volts, 140 watt maximum, 478.8 BTU per hour.


  • CPU performance: 237, MacBench 4


  • GPU: ATI 3D Rage II
  • VRAM: 2 MB built-in SGRAM
  • Video: 12.1″ 800 x 600 at 8- or 16-bit. 24-bit video support may be possible with ATI January 2002 retail drivers, as noted by Rudy V. Pancaro in the archived Twentieth Anniversary Macintosh forum, although the display itself only supports 18-bit output (6 bits per color channel).


  • Floppy drive: 1.4 MB Apple SuperDrive (manual insert)
  • Hard drive: 2 GB 2.5″ ATA/EIDE drive, 136 GB maximum with HFS+ and Mac OS 8.1 or later, upgrades may require some modification as the mounting holes in the original drive bracket do not match newer notebook IDE drives.
  • CD-ROM: 4x SCSI


  • ADB ports: 1 Mini DIN-4, maximum power draw of 500mA total for up to 3 devices, additional port on back of keyboard. Keyboard draws 25-80mA, trackpad draws up to 10mA.
  • SCSI: DB-25 connector on back of computer, supports up to 6 external devices.
  • Serial ports: 2 Mini DIN-9 GeoPorts, with external GeoPort Telecom Adapter capable of 33.6kbps.
  • PCI slots: 1 6.88″ PCI 2.0 compliant slot, 15 watt maximum.
  • Comm slot II: installing an internal modem in the comm slot will disable the modem GeoPort.
  • Other expansion slots: 1 internal pass-through video socket (mirrors built-in screen), 1 internal DAV socket (for use with video editing and ISDN cards)
  • Other ports: 2 F-type tuner connectors for TV and FM, S-video input (compatible with NTSC, PAL and SECAM), 3.5mm 16-bit stereo input and output ports on back and headphone jack in front, Apple PlainTalk microphone included.


  • Dimensions (HxWxD): 17.25″x16.5″x10.0″ (43.8×41.9×25.4 cm)
  • Weight: 14.9 lbs. (6.8 kg)

Accelerators & Upgrades

Online Resources


  • Steve Wozniak noted on Go2Mac.com that, “A volume over 4 GB will not work in a TAM. It causes what appears to be total death in a short time, like when enough of it gets used.”

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