Interfacing old Peripherals

by Rick Calicura

So you have decided to buy a new Mac but you have a bunch of older hardware that you want to keep. The salesman told you not to worry, there are a myriad of adapters and work - a rounds to make it all work together. Well, yes and no.

The older Macs have ADB (Apple Desktop Bus) ports for input devices (keyboards, mice, etc.), serial ports for modems and printers, and SCSI ports for scanners, external hard drives, and the like. The new Macs all have USB (Universal Serial Bus) and many also have FireWire (IEEE 1394 standard).

• ADB supposedly supports up to 16 devices (I wouldn't recommend putting on that many in the real world, however) and transfers data at the rather slow speed of 10 Kbps (kilobits per second).

• A serial port manages a data transfer rate of 230 Kbps and also handles Local Talk, a very easy but slow net-working solution so you could connect Macs together and share printers, etc.

• SCSI (Small Computer System Interface), which includes several flavours such as Ultra SCSI and Ultra Wide SCSI, can handle prodigious data transfer compared to the other ports, up to 5 Mbps (megabytes per second).

You could move one megabyte of data in about a fifth of a second! But it's not always easy to use.

Why USB?

USB is the wave of the future for many peripherals that do not require blazing speed. With USB you can (theoretically) daisy-chain up to 127 devices using one or more powered hubs. With a hub plugged into one of your USB ports, you can keep hanging things onto your Mac and you will be able to "see" them to make them function.

My belief is that USB peripherals are pretty trouble free and should work quite well. But, because USB is slow compared to SCSI, it wont be very satisfactory for big data transfers like video or backups. For printers and scanners, you will love it.

USB to ADB

Let's assume that you have an older Wacom drawing tab-let or Art Pad that uses the Apple ADB (Apple Desktop Bus). But your new iMac or G4 doesn't have an ADB port. There is a wonderful little adapter called the iMate that works perfectly. The ADB adapters work almost flawlessly with older ADB devices, so you generally wont run into a problem.

You may not want to spend the money for a USB-to-serial adapter. My experience with these devices is that they sometimes work with one device on one port but fail to work with another. So I vote "no sale" on USB-to-serial adapters. They are just not reliable.

If you have a Hewlett Packard DeskWriter that uses Apple Talk or Local Talk, you will have better luck with an adapter that converts Ether Talk to Local Talk and using the Ethernet port in your new Mac. but that old DeskWriter is probably only worth about $50 tops and the adapter costs $99!!! You could buy a brand-new Epson 740 at Costco for $89 after the $50 rebate, and you could plug it directly into the USB port on your new Mac.

USB to SCSI

If you have SCSI devices, you can buy a USB-to-SCSI adapter. But be warned, many of these devices support only certain equipment. Be sure to read the manufacturer's list of which devices the adapter supports.

There are a couple of manufacturers of these USB to-SCSI devices: Belkin makes one, but it DOES NOT SUPPORT SCANNERS! Second Wave makes one called SCUSBee. Iomega makes one too, but apparently only for its own devices. Another unfortunate reality of these devices is that they are slow, since USB only handles up to 12 Mbps (megaBITS per second) rather than the faster true-SCSI speed.

The better alternative for your SCSI devices is a SCSI card that you can install in your new G3 or G4 (though not in your iMac, unfortunately). Adaptec makes a lovely little SCSI card for about $50, and you can daisy-chain your SCSI devices (following SCSI rules) with virtually guaranteed success. The less expensive SCSI cards won't support a startup device, but for a few dollars more you can purchase one that will.

Beyond USB

FireWire is aptly named. It moves data like lightning. FireWire (which Sony calls "i.Link") will transfer data 400 Mbps (50 Mbps). The rule for FireWire is a maxi-mum cable length of 15 feet, but you can add a hub to extend the distance. You can plug a FireWire device right into your Mac while it is running, a definite no-no with ADB, serial, and SCSI. This technology is ready for prime time and definitely worth looking into. A new "USB 2" has been touted as being faster than FireWire, but I suspect that that is just wishful thinking on the part of Intel and others who are behind it.

sad comedown from the old Apple Extended Keyboard. It seems odd that Apple, after such brilliant design work on the G3s, G4s, and iMacs, should drop the ball so resoundingly with this keyboard and the irritating hockey-puck mouse.

I tend to agree with many who prognosticate that USB will probably remain a good bet for things like printers, but FireWire will thrive with things like video, scanners, CDR, and DVD-RAM devices. As older peripherals wear out, we will see USB and FireWire really begin to take off.