Retro and Then Some – The Beige G3

The Beige Power Macintosh G3 (BG3) is the bridge machine to the distant Apple past. It is the last Macintosh with an Old World ROM, meaning it still supports pre-1998 technologies: Mac floppy drive, ADB I/O, Mac serial RS-422 I/O, built-in SCSI, bootable support for Mac OS 9.2 and prior operating systems. Yet BG3 can appear as a modern, albeit slow, Macintosh system through its ability to run OS X and host modern I/O interfaces via PCI adapters. BG3 is the only Macintosh with Old World Rom that can boot into OS X. Over 1.6M units were sold, with list price between $2000US (base model 8/98) and $2800US (loaded model 1997). It was discontinued in January 1999.

BG3 is the Rosetta hardware for Macintosh early retro-computing, spanning the old (pre-2K) and new (post-2K) worlds, with native support for both. Of course, going back to a transitional machine means plunging into a soup of incompatibilities and gotchas. Modern machines have spoiled us, so that we forget the frustrations of getting the old stuff fired up and working properly. Further, expeditions into unsupported operating systems means extra hours of headaches. And so much time has passed that the forums for answering questions have long since closed up shop. It’s not for the faint of heart.

But those with nostalgic tendencies and legacy software/hardware appetites will likely investigate using a BG3 as an auxiliary server. I am one such; my BG3 has the desktop outrigger style case, purchased with monitor for $20. It is normally booted into OS9, although it has an OSX partition that facilitates administrative tasks in a more modern environment. It runs those OS9 applications of mine that have proved not compatible with the Classic environment. It also allowed me to retrieve all the data I had long ago stashed on Apple-formatted floppy disks. Surprisingly, most of it was readable.

We gearheads enjoy doing the most with the least; it is energizing to explore what the old girl is capable of. And it is fun to defeat the obsolescence gates that Apple has erected over decades to keep its users marching steadily forward in lock step, buying the newest stuff (strange twist on Apple’s 1984 commercial). Additionally, one ends up with a perfectly usable backup/guest computer.

OS X on the BG3 can be accessed via screen sharing from my iMac. Screen sharing between Mavericks and OS X 3.9 couldn’t be easier. One simply installs the free Apple Remote Desktop Client 2.2 under Panther. It contains a Bonjour-savvy VNC server that will communicate with Snow Leopard’s built-in VNC client. The server is enabled via the Remote Desktop settings in the Sharing preference pane of Panther.

The remainder of this discussion describes ways of pumping up a BG3 and will be of interest only to obsessive tinkerers.

BG3 Hardware Performance Upgrades

BG3 evolved in three different, upgradable ROM configurations. The RevC ROM machines shipped with ATI Turbo Rage Pro video on the logic board. The RevC ROM version is the best choice for hosting OS X, and what follows is predicated on this version.

To maximize the modern capabilities of BG3, hardware upgrades are implemented. My starting old-mac configuration is a 300MHz RevC BG3 with 320MB DRAM, and a 6GB 5400 RPM HD, and 6MB of on-board video VRAM. Upgrade goals are:

  • higher performance
  • increased storage capacity
  • expanded interfaces
  • more modern OS support

Increasing Processing Speed

Higher performance is achieved by higher clock rates for CPU and memory bus, expanded physical memory to avoid excessive paging to disk, a faster video component, faster ethernet interface, and faster hard drives. There are smallish incremental increases to be had in these areas, and any improvement will make the computer more usable in OS X. A pricey CPU upgrade would provide the only large driver for increased performance.

768MB of DRAM can be configured, via 3 x 256MB low-profile DIMMs. Maximum DRAM is desirable if OS X is to be utilized without annoyingly sluggish behavior; this is barely half of what modern OS X machines ship with as a minimum. More modern 133MHz and 100MHz DIMMS can be used to ensure best performance.

The CPU is on a ZIF-socketed board, so is easily replaced. A variety of G4 and G3 accelerators were available and occasionally but rarely show up on eBay. Such an upgrade is still somewhat pricey, possibly more than doubling the investment. Therefore, overclocking the stock machine is the best bang for the buck. Also in my experience, such upgrades are unreliable in their old age (random freezes, etc)

G4 and G3 chips, running at the same speed, offer equivalent processing power for most applications. The G4 is required to run Leopard, however, because of Leopard’s reliance on G4-specific altivec and video features. The G4’s floating point performance is substantially improved over the G3, but most all applications and OS X itself only require integer arithmetic.

The BG3 can be overclocked. The only caveat regarding increased CPU performance: in very rare cases, BG3s were produced with a Royal VRM (voltage regulator module), and these cannot be safely accelerated. A replacement VRM must be installed on the logic board. A 300MHz CPU can easily run at 350MHz or even higher. The memory bus speed can also be overclocked, from 66.7MHz up to 75MHz, and rarely all the way to 83MHz.

Overclocking is achieved by placing 2mm jumpers on a jumper block on the logic board. First one must remove the seal that voids the warranty (not a heavy concern on a 13 year old computer of nil market value), then remove the stock jumper block cap that sets the as-shipped parameters. The jumper positions control the bus speed and the CPU multiplier (up to 8X the bus speed). Thus, setting a bus speed of 70MHz and a CPU-multiplier of 5X would require a chip capable of running at 350MHz.

Overclocking is a trial and error process. CPU multipliers are increased until the machine no longer runs. Then the next lower value can usually safely be permanently enabled by jumper. I tried 394MHz, but got no chime. Then I tried 385MHz and 366MHz, both of which gave a chime, but the BG3 wouldn’t boot. So the 70MHz bus with 5X multiplier (350 MHz) is the winning combo on this BG3. And this provides a slightly overclocked PCI bus for increased performance there too.

The stock 5400RPM hard drive can be replaced by two 7200RPM drives, each on a separate ATA bus. These newer, faster drives also have much larger caches, 8160KB vs 512KB. With the RevB or RevC ROMs, a master and slave device can be hosted by each internal IDE bus. But only a master device can be booted, meaning at most two internal IDE devices are bootable, one for each IDE bus. Since the primary hard drive and the CD-ROM drive should both be bootable, a second internal-bus IDE hard drive must be slave and hence non-bootable. To have an additional bootable drive, the second drive should be connected to the internal SCSI bus, or via a PCI-IDE adapter card.

Increasing Storage Capacity

E-IDE/ATA hard drive capacity is limited to 128GB by the architecture of each internal IDE bus. To use a larger IDE drive, a PCI-IDE adapter card should be installed. Since slots are at a premium, and since the internal SCSI bus has no such limitation, a large SCSI drive in place of the second IDE drive will succeed, offering roughly equivalent performance to the IDE bus.

SCSI drives of up to 320GB were produced, but these were meant for the fastest SCSI channel architecture and hence available only with LVD Ultra-SCSI interface, requiring a special cable or adapter to use with the 50-pin single-ended internal SCSI bus.

Expanding Interfaces

The BG3 came with all three PCI slots filled:

  • USB 2.0 card
  • Firewire 400 card
  • ATI Rage 128 with 16MB VRAM (enhanced video)

I removed the existing firewire PCI card to make room for a fast ethernet card (since the main computer on the LAN has built-in firewire for use when needed). I managed to find an appropriate driver for the ethernet card, from the chipset manufacturer, that would allow it to run at 100Mbps. The existing PCI USB2.0 interface works entirely PnP.

BG3 Mac OS Options

For those not wanting to boot only in OS, a BG3 can install and boot from OS X Jaguar natively. A BG3 can be made to run all OS X versions up through Leopard, but the hoops one must jump through increase steadily as one gets later in the OS X cycle. Panther and Tiger can be installed on a stock BG3 using the utility XPostFacto (XPF, versions 3.1 and 4 respectively); Leopard, however, also requires a G4 processor upgrade.

After installing an Apple-unsupported version of OS X via XPF, any subsequent boot process and/or startup disk selection becomes permanently dependent on XPF-installed .kext files and modified bootx file. The kernel extensions support such features as serial RS-422, ADB, and the onboard graphics engine, which are added back via XPF even though they were dropped by OS X Panther and above. There is no floppy drive support in OS X, but floppies are a legacy that have no use in a modern world. Once all one’s retro-data has been retrieved from one’s floppy archive, the whole bunch can be tossed (erm…, make that recycled).

Panther 10.3.9 seems the easiest/best choice of OS X for a BG3, although Jaguar 10.2.8 works okay. Panther is more mature, more feature-laden, and is said to run faster than Jaguar on a BG3. Tiger and Leopard get pricier to support, because of their requirement for a DVD drive or firewire support, and in the case of Leopard, a G4 upgrade.

OS X versions through Panther were distributed on CDs, so the BG3’s stock CD-ROM drive supports the OS install. Tiger and later were distributed on DVD. If one has upgraded the BG3 CD-ROM to a superdrive, this is no problem. Otherwise, some report success by swapping in a HD with OS X installed by a more modern computer, or installing the OS X target version via firewire target disk mode from a more modern computer with DVD support. But having only Intel Macs at the time, the target disk is not readable by the BG3, so this was not an option for me. It would most likely work if another PowerPC machine with built-in firewire were attached.

Aside: I have since acquired two G4 Powerbooks, 12″ 1.33GHz and 15″ 1.67GHz, under $50US each on eBay, to transform a hole in my retro-platform architecture into a sweet spot. The 12″ is my main transportable computer, and is configured to run OS9 Classic within Tiger, with TenFourFox and TenFourBird as modern (tabbed) mail and browser interfaces. Now my OS9 game nostalgia is supported on the road. The 15″ running Leopard sits alongside my late-2009 27″ iMac, where it serves as back-up and provides a second screen when needed; it is further configured as a mobile digital audio recording workstation, via its FW800 interface.

OS 9 and OS X Co-existence

Most of BG3 users likely keep their machine for OS9 utilization, so both OS 9 and OS X likely will exist on the bootable drive(s). Some OS X users will also use Classic Environment within their OS X system for running concurrent OS 9 applications. The Classic Environment OS 9 system is frequently a stripped-down system, to enable faster loading of the environment. The minimized Classic Environment works fine when installed on the OS X partition.

Thus there are three common configurations for an OS 9/X support:

single partition, OS X + Classic
two partitions: OS X, Classic
three partitions: OS X, Classic, full OS 9.

With multiple drives, one need not partition to create the OS separation. But if partitioning is used, it should be performed by booting from the OS9 install CD, then using Drive Setup to partition the disk. An OS X partitioning will not be recognized in OS 9.

My BG3 has two internal drives; the primary is bootable, the secondary for data. The primary has a full install of OS 9.2.2 in a small partition. The large 7.5GB partition hosts OS X 10.3.9. I keep the OS 9 as a minimal system install, so it serves the purpose of the Classic Environment as well.

Use of XPF to install Panther/Tiger

XPF 3.1 will run under either OS 9 or OS X 10.2 or later. The most straigntforward XPF approach installs XPF in the OS 9 drive/partition, from where it is run to install the target OS in the OS X partition from CDs. In my BG3, the 10GB boot drive contains both OS 9 and OS X in separate bootable partitions.

The BG3 imposes some disk limitations on its users via its onboard IDE bus implementation. The OS must always reside in the first 8GB of the boot volume. And the maximum drive size that can be mounted on an internal bus is 128GB; if a larger volume is mounted, only the first 128GB can be used. A separate PCI-IDE adapter can remove the 128GB drive size limit.

Installation is in two steps. On first executing XPF, it will ask for source and target volume information, then copy some special .kext files and a modified Bootx program to the target. It then reboots into the OS X install CD for performing the full OS X installation on the target volume. But since the install should not overwrite files previously placed on the target drive by XPF, a clean install should not be selected.

Results and Cost of Retro-Computing Habit

After upgrades, the BG3 currently runs at 350MHz with bus speed of 70MHz and a cache speed of 175MHz (+15%), with 768MB DRAM, a fast ethernet PCI card, and 2 internal 10GB 7200 RPM hard drives; I had a couple of old IDE drives laying around. MacBench shows a raw disk performance increase of 50%, and a Publishing Disk test performance increase (real world) of 15%. The Internet connection speed test shows peak observed 14.4Mbps downlink, 2.5X the speed through the built-in 10BaseT circuit (not too shabby for a sub-$5 investment). This compares favorably with the 25Mbps downlink that big-mac obtains from the shared FIOS broadband.

Cost of Habit To Date:
$20.00 Rev C Beige G3 w/ Princeton Graphics EO72 17″ Monitor, ADB KB/Mouse
$ 4.60 New logic board battery
$ 8.89 Additional 512MB DRAM
$ 8.99 Sled for 2nd internal HD
$ 8.75 36″ 2-device IDE cable
$ 1.99 pkg 10 2mm jumpers for speed settings on logic board
$ 4.88 D-Link DFE-530TX+ PCI-FastEthernet adapter
$ 2.99 SATA-eSATA cable 20″
$ 2.95 eSATA-USB2 adapter
$ 0.00 2 x 10GB, 7200RPM IDE HD (found in attic)
$ 0.00 700GB external SATA HD (found in attic)
$ 0.00 Mac OS X Panther (installed from existing CDs)
$ x.xx Labor: Priceless

$63.04 Total


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