Mac OS X, SCSI, and the Beige G3
After reading Power Mac G3 (beige): A
Good Buy, Dan Yarberry comments:
I question this statement in the just-updated blurb on Beige
G3s:
"Although we consider the beige G3 a best buy for the classic Mac
OS, we cannot rate it as highly for OS X, since many features (SCSI,
the floppy drive, GeoPorts, fully accelerated graphics, etc.) are
unsupported...."
The only part I question is "SCSI".
I have a Beige G3 MT, 333 MHz, with Apple-stock UW SCSI PCI card and
9 GB UW SCSI hard drive, to which I added a 4 GB UW SCSI
drive and memory to 384 MB total. I have OS 10.2 on the 4 GB
drive, OS 9.2 on the 9 GB drive. I have an external Zip drive,
Nikon film scanner, and external DVD-RAM drive chained to the separate
motherboard SCSI bus. All these SCSI devices work under OS X.
(Except the Nikon scanner doesn't have an OS X driver, and I
therefore use it only under OS 9. But it's in the chain while the
other devices are in use under OS X.)
(I also have a 2-port PCI USB board, to which are attached a printer
and a flatbed scanner. This scanner also doesn't have an OS X
driver, but does work under Classic.)
I use OS X as the primary environment, and only use OS 9 by
exception (e.g., for the film scanner, which doesn't work under
Classic). And, incidentally, I don't find the OS X performance
objectionable (perhaps because I'm not used to anything faster.)
I'm not sure exactly what I was thinking when I penned those words
in September 2001. (The article was significantly updated this past
week, but that paragraph wasn't touched.) If I recall correctly, there
were a lot of problems with third-party SCSI cards and drivers for SCSI
devices back then, but that's no longer true.
Regardless, the onboard SCSI has always worked under OS X, so I've
revised that paragraph to remove the outdated reference to a lack of
SCSI support.
Thanks for bringing this to my attention.
I also find OS X performance generally acceptable on the beige G3/333,
but a fair bit of that is due to adding a faster hard drive and hard
drive controller - as you've done on yours. The stock drive and slow
IDE bus are definitely a bottleneck on the beige G3.
CoreCrib Not a Good Value
After I concluded that buying a CoreCrib could save money over
picking up a new, used, or refurbished Power Mac G4 in Does Building
Your Own CoreCrib G4 Make Economic Sense?, Peter da Silva writes:
Subject: I don't see the CoreCrib making sense at that price...
Even going to
eBay a couple of times for components and software, you're looking
at $1,200 for the whole system. If you go with real vendors, add at
least $150 to that. The result is an 800 MHz G4 with no monitor and no
support for the price of a top-end eMac or entry-level iMac. For another
$150 you can get a brand new 1 GHz G4 direct from Apple or a 14" iBook.
I could see it at most half that price - or with an OS and support
from Apple. But almost $400 for a case, power supply, and naked
motherboard? Um, I'll pass...
The CoreCrib allows Mac users to do something Apple hasn't let us
do since the era of the Mac IIci
- buy a bare bones computer and build it the way we want it. Believe
me, when I worked at ComputerLand of Grand Rapids, we sold a lot of
SEs, SE/30s, IIcxs, IIcis, and other Macs that we
ordered in the minimum floppy-only configuration and upgraded with RAM
and third-party hard drives for our customers.
Not only did this let the customer get exactly the configuration they
wanted and allow the store to generate additional profits (something
sorely lacking in Mac sales these days), but the third-party memory and
drives generally had better warrantees than Apple products, too.
The CoreCrib isn't competing with the essentially unexpandable eMac,
iMac, or iBook. It's intended for the Mac user who wants expansion
options, and depending on how much can be moved older from an existing
Mac, the cost of a CoreCrib can range from under US$400 to over
US$1,200. It's not for everyone, but I believe there is a market for
this box.
Yes, it would be even better if Apple offered a bare bones G4, but they
seem much more interested in selling fully assembled systems at a
substantial markup (the Power Macs and PowerBooks have the highest
profit margin in the Apple line). Core goes way beyond the
build-to-order options available through the Apple Store, and if they
can tap into a market Apple is ignoring, we all benefit.
More on CoreCrib Value
Andrew W. Hill writes:
"Has it been worth it? I think so. Picking up a used G4/733 or
G4/867 from a dealer would set you back about US$1,500 with less
memory, a smaller hard drive, no ability to watch DVDs, and less drive
bays"
Alternately, you can buy a brand new G4 @ 1 GHz, although with less
memory and a slightly smaller hard drive, but still the ability to read
DVDs and burn CDs also for $1500. While its an easy sell to claim a
$200 savings over the used G4s, it's much harder to say that building
your own system of old parts is worth the $200.
How much you save depends on how much you already have that can be
used in the CoreCrib. Assuming no parts and no copy of the Mac OS,
someone could build an 800 MHz system for $200-300 less than a
comparable new or used Power Mac G4. Whether that's the best value is
up to the individual buyer; I was only making the case that the
CoreCrib can make economic sense.
One benefit I didn't mention in the article is that having separate
DVD-ROM and CD-RW drives probably means you'll be able to burn CDs a
whole lot faster than Apple's Combo drive permits. Even the 48x and 52x
burners have become cheap these days.
I've also since discovered that Core is selling fully configured
systems - just add a copy of the Mac OS - for as little as
$700. Their 800 MHz setup is pretty similar to the one I came up with,
lacking a DVD player, keyboard, mouse, and OS. It sells for $1,000 and
eliminates the need for the end user to put all the parts
together.
iMac Upgrades
After reading Upgrades for the Tray-Loading
iMac, Julian O'Connor writes:
Regarding your recent article on May 12th on the iMac channel.
There was a graphics upgrade path for iMac Revisions A and B - the
mezzanine slot. The Micro Conversions (or later, G-Links) iMac Game
Wizard attached to the Mezz slot and featured a Voodoo 2 chipset.
7200 RPM Hard disks do not necessarily make a difference to
performance. I put such a drive as described in your article in my slot
loader iMac - primarily because the original was so noisy. It was a
Maxtor 6 GB 5400 RPM model.
Boot up time and shut down time remained unchanged.
I did file seaches for the character A and set a time limit of five
minutes. A similar search was done with the character B for 2.5
minutes. A very similar number of files was found in both searches in
the alotted times.
The only improvement was searching for an actual word and measuring
the time taken to find all files containing that word. An average
improvement of 15% was measured.
I believe that the IDE bus speed of the early slot loading and tray
loading models prevents exploiting the capabilities of large cache,
7200 RPM hard disks.
I didn't mention the handful of mezzanine cards made for the Rev. A
and B iMacs because they're pretty rare. Of the millions of
tray-loading iMacs out there, I doubt even thousands of mezzanine cards
(whether video, SCSI, or anything else) were ever sold. A search of
eBay shows no such cards for sale.
Although I can't find any information on Apple's site about the IDE bus
on the tray-loading iMacs, I strongly suspect that it's the same 16.67
MBps bus used in the beige G3s. Most drives of that era couldn't
saturate such a bus, but all but the cheapest drives made in the past
three years offer higher throughput that that.
If you had a 5400 rpm drive, you were better off than some iMac owners.
Apple wanted to keep costs down, so if they could save money by buying
4400 rpm drives, they did so. Those with 5400 rpm drives may notice
little or no improvement, as you've discovered. I've updated the page
to reflect that Apple sometimes used 4400 rpm drives and sometimes used
faster 5400 rpm drives.
Regardless of rotational speed, the buffer can only feed information as
fast as the data bus will accept it, which may reduce the benefit of a
larger cache/buffer, but it won't eliminate it.
More on the Dash 30fx
David Thornton writes:
Here are three other photos
for you, showing what's behind the front panel (lots of room for
expansion), the I/O panel underneath the top cover (cabling exits
through a gap in the back), and the logic board. The big white thing in
the middle of the innards picture is called the "Doghouse", and
provided cooling for the memory. Apparently the memory supplied for
these babies was rather delicate, and could be cooked pretty easily.
I've got a 14-page Memory Installation Guide that came with the memory
upgrade that was purchased for it.
Since my last note I've spiffed the thing up a bit with a 7.6.1
install and put it back to work running MacDNS for the department. I
was surprised to find it to be a bit more responsive in resolving
domain names than an old Quadra
950 that was pulling DNS duty for us.
Thanks for the photos. I've created a separate page to display
them.
How to tell if a Biege G3 has Rev A ROM
Jeffrey Harris
We have an accelerated (to 500 MHz) Beige G3 with ~500 meg RAM, a 20
gig HD, and a Zip drive in the lab running sys 9.2. I am thinking about
loading Jaguar onto it.
But before doing the work - how do I check the version of its ROM?
Does the presence of the Zip (presumably running in slave mode)
indicate that it is Rev B, not Rev A, already?
Thanks, and keep up the good work.
I can't believe I haven't published that information on Low End Mac
before. There are three ROM revisions for the beige G3. Rev. A ROMs
have a 1997 copyright and were only included with the Rev. 1
motherboard, which also included ATI Rage II+ video. Rev. B and C ROMs,
which can apparently be installed on the Rev. 1 motherboard to overcome
limitations of the Rev. A ROM, have a 1998 copyright.
You can also identify a Rev. 2 motherboard by looking for ATI Rage Pro
video - or use the Apple System Profiler and have the computer report
which video is installed. (At least in more recent versions of the Mac
OS.) The Apple System Profiler will also report a ROM number. Here's
the info to ID the three ROMs:
Rev. 1: $77D.40F2 ©1997
Rev. 2: $77D.45F1 ©1998
Rev. 3: $77D.45F2 ©1998
I'll be updating the beige G3 profiles and the best buy page to reflect
this.
Dan Knight has been publishing Low
End Mac since April 1997. Mailbag columns come from email responses to his Mac Musings, Mac Daniel, Online Tech Journal, and other columns on the site.
