Earlier this week I suggested that
slot-loading iMacs were a better choice than the earlier tray-loading
models if you want to run Mac OS X. Today I will explain why.
The slot-loading iMacs were introduced in October 1999 at speeds of
350 MHz and 400 MHz. Over time, the
slot-loaders achieved speeds as high as 700 MHz. Improvements over the
tray-loading iMac included a 100 MHz system bus (vs. 66 MHz), a
slightly smaller enclosure, and nearly silent operation - there was no
cooling fan in the slot-loaders.
They also addressed the two biggest drawbacks of the earlier iMacs.
Unlike the tray-loaders, all of the slot-loaders support up to
1 GB of memory. And all of them let you use the whole hard drive
(up to 120 GB) for the operating system, applications, and work
files.
Slot-Loader Basics
The slot-loading iMacs had a 15" CRT display, moderately slow hard
drives (6-7 GB on the low end, and up to 60 GB on later models), and
had a variety of media drive options. Some shipped with a CD-ROM,
others had DVD-ROM drives, and later models generally included CD-RW.
(The slot-loading iMac was never shipped with a Combo drive or
SuperDrive, but there are third-party
CD-RW, Combo, and SuperDrives available for as little as
US$39!)
The hard drive is a standard IDE mechanism, and you can install
drives up to 120 GB in size. A fast drive with a large buffer is always
nice, and throughput is limited to 33 Mbps - twice as fast as on
tray-loading models.
Most slot-loaders have FireWire ports, but the entry-level 350 MHz
models left it out, so if you want to use FireWire devices, stick with
400 MHz and faster iMacs.
There were three, four, or five different versions of slot-loading
iMacs depending on how you want to count things. Here's a quick
overview (also see our Quick Guide to CRT
iMacs):
- Version 1 (Oct. 1999): 350-400 MHz G3, 64-128 MB RAM
standard, 6/10/13 GB hard drive standard, 24x CD-ROM or 4x DVD-ROM,
v.90 modem. Supports 1 GB RAM. 8 MB video RAM. ATI Rage 128VR
video chipset. Requires Mac OS 8.6 or later. Colors: blueberry,
strawberry, grape, lime, tangerine.
- Version 2 (July 2000): 350-500 MHz G3, 64-128 MB RAM
standard, 7-30 GB hard drive standard, 24x CD-ROM or 4x DVD-ROM, v.90
modem. Supports 1 GB RAM. 8 MB video RAM. ATI Rage Pro 128
video chipset. Requires Mac OS 9.0.4 or later. Colors: indigo, sage,
ruby, graphite, snow.
- Version 3a (February 2001): 400-500 MHz G3 with backside
cache, 64 MB RAM standard, 10-20 GB hard drive standard, 24x CD-ROM or
8x CD-RW, v.90 modem. Supports 1 GB RAM. 8 MB video RAM. ATI
Rage Pro 128 video chipset. Requires Mac OS 9.1 or later. Colors:
indigo, flower power, blue dalmatian.
- Version 3b (February 2001): 500-600 MHz G3 with onboard
cache, 64-128 MB RAM standard, 20-40 GB hard drive standard, 8x CD-RW,
v.90 modem. Supports 1 GB RAM. 16 MB video RAM. ATI Rage Ultra 128
video chipset. Requires Mac OS 9.1 or later. Colors: graphite, flower
power, blue dalmatian.
- Version 4 (February 2001): 500-700 MHz G3, 128-256 MB RAM
standard, 20-60 GB hard drive standard, 8x CD-RW, v.90 modem. Supports
1 GB RAM. 16 MB video RAM. ATI Rage Ultra 128 video chipset.
Requires Mac OS 9.1 or later. Colors: indigo, graphite, snow.
In brief, the 1999 model has Rage 128VR video, while version 2 and
3a have Rage Pro 128 graphics. Versions 3b and 4 use the Rage Ultra 128
chipset and have 16 MB of video memory, twice as much as the earlier
slot-loaders. These last two versions also include an improved G3 CPU
with the backside cache built right into the processor.
OS X Suggestions
With enough memory, the slot-loading iMacs can run Mac OS X
comfortably. The slower models are no speed demons, but they're
functional, and later iMacs with improved video and improved versions
of the G3 acquit themselves quite nicely.
The first thing you need to get the most out of OS X is plenty
of memory. Although you can run OS X with as little as 128 MB of
RAM, you won't be happy doing so. OS X will use your Mac's hard
drive to create virtual memory when it runs out of RAM, and that's
several orders of magnitude slower than memory chips, so you want real
RAM.
I'd call 256 MB an absolute minimum for decent OS X
performance, 320-384 MB better, 512-640 MB comfortable, and 768 MB to
1 GB ideal. It's not cheap, but it's the best investment you can
make if you want to unleash OS X on any Mac.
The next way to trick out a slot-loading iMac is with a faster hard
drive. I'm a big fan of those 80 GB 7200 rpm drives with an 8 MB
buffer that are often on sale for around US$80. You may be able to find
smaller drives for a bit less, but it's often just a little bit less.
You can use drives as large as 120 GB if you need lots of space - those
160 GB and larger drives require a version of the IDE specification not
supported on G3 iMacs.
The faster hard drive not only offers faster data access, it makes
virtual memory faster as well (the faster IDE bus helps, too).
Avoid used hard drives. Pulls, drives taken out of a new computer so
a faster and/or higher capacity drive can be installed are often good
deals - when you can find them.
Processor Upgrades
Sometimes a CPU upgrade makes
economic sense. If you already have the iMac, have all the RAM you
want, and have a good hard drive, expending $299-349 to perk up
performance makes sense - and the slower the CPU in your iMac, the more
sense it makes.
At this point I know of only two CPU upgrades for slot-loading
iMacs:
The iTechDV will offer superior number crunching power, which means
faster Photoshop filters, iTunes ripping, and video editing. Unless you
do a lot of that, the 900 MHz iForce is probably your best bet. On
slower iMacs, it can more than double performance, and even the fastest
G3 iMac ever made will be faster with it.
Don't plan on buying an iMac and then adding a CPU upgrade. By the
time you do that, you may as well ante up for a nice used 700 MHz to
1 GHz G4 eMac, which will also give you a larger display. But if
you already own a slot-loading iMac and want more power, processor
upgrades may make sense.
Optical Drives
The biggest drawback of the slot-loaders may be their optical
drives. Apple never offered a Combo drive, so you'll have to choose
between CD playback only, CD and DVD playback, or CD playback and
recording when you pick an iMac. But you're not stuck there. You can
pick up a CD-RW/DVD drive for as little as US$45, which means your 400
MHz or faster iMac will be able to play DVDs and burn CDs. Recommended,
particularly if you have a CD-ROM or DVD model.
Oddly enough, Combo drives cost less
than CD-RW drives!
Conclusion
Upgrading slot-loading iMac so you can use OS X won't cost as much
as upgrading a tray-loader. The hard drive is already large enough,
although I'd find 6-10 GB very limiting very quickly. And you can add a
single 256 MB of 512 MB memory module to boost RAM to a very
comfortable amount, which is less costly than buying two modules for a
tray-loader.
If you want to replace the CD-ROM, DVD, or CD-RW drive, you have the
option of a Combo drive - and even a SuperDrive if you want to burn
DVDs. (If that's an interest of yours, get a fast iMac or consider one
of the faster CPU upgrades.)
With prices starting at US$209 for an iMac 350 (no FireWire)
and US$300 for a 400 MHz iMac with FireWire, the slot-loading iMac
is definitely worth the small price premium compared with the
tray-loaders. With lower cost add-on optical drives, support for
1 GB of RAM, and no 8 GB partition issue (which the
tray-loaders suffer from), it's a great way to go OS X on a
budget. 
Revised 2004.09.13 to add colors of various models.
