Umax SuperMac J700

The SuperMac J700 (Centauri in Europe and Asia) was Umax’s least expensive computer based on the PowerPC 604e processor. Very expandable, it has 4 PCI slots, 5 drive bays, 8 DIMM sockets, and a replaceable CPU.

Umax SuperMac J700

The J700 uses the same CPU daughter cards as Apple’s Power Macs from the same era, giving the SuperMac J700 owner lots of processor upgrade options.

RAM can be interleaved to improve performance.

The motherboard is the same as that in the S900 except that only 4 of 6 possible PCI slots are installed and the second processor slot hasn’t been installed. This means it should be possible to have a 6 slot, 2 processor J700 by upgrading with an S900 motherboard.

Umax offered an optional E100 card with UltraSCSI and 10/100 ethernet.

Umax was the only clone maker to acquire a Mac OS 8 license from Apple, and the version 5 installer CDs shipped with Mac OS 8.


  • J700/150 (Centauri 1500). 150 MHz CPU, 50 MHz bus
  • J700/180 (Centauri 1800). 180 MHz CPU, 45 MHz bus
  • J700/233 (Centauri 2330). 233 MHz CPU, 46.67 MHz bus


  • J700/150 introduced 1996.07.01, discontinued 1997.02.01
  • J700/180 introduced 1996.10.01, discontinued 1998.08.31
  • requires System 7.5.3 through 9.1
  • CPU: 150 MHz 604, 180-233 MHz 604e, upgradable with standard daughter card
  • performance (180 MHz 604e): 85, Speedometer 3; 11.9, Speedometer 4; 44.7, MacBench 3
    see Benchmarks: SuperMac J700 for more details
  • bus: nominal 50 MHz (varies from 45 to 51.428 MHz, depending on the speed CPU)
  • RAM: 24 MB standard, 16 MB soldered on the motherboard, expandable by an additional 1,024 MB (1 GB!) using 8 DIMM slots and 70ns 5 volt EDO or fast-page DRAM. Additional memory can be interleaved.
  • Video: ixMicro Twin Turbo Graphics Accelerator standard with 2-4 MB VRAM, resolutions to 1920×1080, 24-bit color to 832 x 624 with 2 MB VRAM, to 1152 x 870 with 4 MB.
  • L2 cache: 512k, not upgradable
  • hard drive: 2.1 GB SCSI-2
  • CD-ROM: 6.7x (150 MHz), 8x (180 MHz), or 24x (233 MHz)
  • Zip drive: optional
  • Internal Fast SCSI-2 bus and external SCSI-1 bus (upgradable to Ultra Wide SCSI-3 with E100 card)
  • ADB: 2 ports for keyboard and mouse
  • two miniDIN-8 GeoPorts on back of computer
  • DB-25 SCSI connector on back of computer with SCSI-1 support
  • PCI slots: 4
  • ethernet: built in, upgradable to 100Base-T with E100 card
  • size (H x W x D): 6.5″ x 16.5″ x 17.25″
  • weight: 28 lb.

Accelerators & Upgrades

Online Resources


  • The J700 and S900 have a PCI bridge chip controlling all PCI slots except the first two, which use the normal Apple chip. As a result, only cards that are PCI 2.1 compliant can be installed in slots 3-6 (3-4 for J700). Problematic cards are usually older SCSI cards, and, for some reason, ixMicro cards such as Ultimate Rez (but not the older ixMicro Twin Turbo cards). There are claims that even ixMicro-branded cards have slot preference, and in a multiple-card setup at least one has to be in slot 1 or 2, while the other can be in slot 4 or 5.
  • Newer Tech recommends against using EDO memory in the J700 and S900, because these models have “occasionally exhibited some problems when running with EDO memory. These problems tend to become more pronounced when updating your machine with a G3 card. . . . Therefore, we are recommending people to stick with FPM (Fast Page Memory) in these machines. If you are already running EDO memory without apparent problems, we certainly don’t mean to imply that you should be having problems, merely that you could have some.”
  • Umax suggests updating the J700 and S900 to version 2.0.2 of the Licensing Extension if you’re using Mac OS 8 or 8.1. <>
  • The version of FWB Hard Disk Toolkit that ships with most SuperMacs is not compatible with Mac OS 8 or later. You must use version 2.0.6 or later, available on the Umax software updates page. Be sure to install the new drivers on your hard drive before you run the OS 8 installer. Also, you must be sure that you do not update the driver on your hard drive during OS 8 installation. Using an older version of FWB HDT or the Apple driver on the SCSI drive that came with the SuperMac may so botch the hard drive structure that you will need to reformat it and reinstall everything. (As always, you should do a full backup before installing new drivers or updating your operating system.)
  • If your monitor is coming up green with extensions off or until the entire system is loaded, you can adjust the TwinTurbo card to change this behavior. Be sure the computer is off, disconnect the monitor, remove the cover, ground yourself by touching the power supply, the carefully remove the video card. Next to the video ports is a jumper marked JP4. Remove it from the two pins it’s on and move it to the other end (it must still be on the middle pin). Reinsert the card, connect your monitor, and do a quick boot with extensions off (hold down the shift key while starting). If it’s not green, shut down the computer, seal it up, and go back to work. If the green should persist, put the JP4 jumper back where it was. (According to Sync on Green Returns on Restart, the 8 MB card does not have a JP4 jumper.)

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