The age of the multimedia portable computer is here. The latest breed of notebook computers come with built-in speakers, microphone and stereo sound capabilities - and many offer add-on CD-rom drives as an option.

This might seem an overuse of resources for a portable computer. But a skim through any recent computer magazine will show that CD-rom software is where the market is moving, and notebook computers cannot afford to miss out on this - at least that's whatmanufacturers would have you believe. That's why they are commonly offering three routes to using a CD-rom drive with a notebook computer.

The quickest and latest way to start using a CD-rom with a notebook computer is to buy one with a CD built into it. Manufacturers such as Panasonic, IBM and Toshiba offer notebook systems with built-in CD-rom drives. But that is expensive. - such systemsstart at £3,500. They are heavier to carry (due to the weight of the CD-rom and the electronics needed to drive it) and draw more quickly on the batteries. But for anyone who does need to use CD-rom software on the move, systems such as the Panasonic CF41, the IBM ThinkPad 755CD and Toshiba's T6600C offer a combination of convenience, flexibility and power.

The design of the CD-rom in each of these systems is a little different. IBM puts the CD-rom tray at the front of its ThinkPad 755CD, while the Panasonic CF41's CD-rom is unusually located under the keyboard. Toshiba's T6600C is a larger system, aimed more at the mains-powered portable market, and features a CD-rom mounted at the right-hand side of the system.

A second, more common approach to bringing multimedia to a notebook PC is via a "docking station'' in the office into which the notebook machine slots. These often have room for standard desktop CD-rom drives, which are cheaper than portable versions. This is one choice for those who need CD-rom capability at a single location - but a cheaper option is to buy another desktop computer equipped with a CD-rom.

The final option is to buy a portable CD-rom drive, and connect it up to the notebook machine. But amateurs may find the technical details daunting. The connection is made either through the computer's PCMCIA expansion card slot, or through its parallel printer port. Most new notebook systems include PCMCIA cards slots, and notebook add-on suppliers sell PCMCIA cards that contain a high-speed Small Computer Systems Interface (SCSI).

CD-rom drives that can be connected through the printer port are common, costing £200 to £300. These provide a built-in "parallel to SCSI converter'' that not only converts the printer interface so it can communicate with the drive, but also provides a "pass-through'' printer connection so you can still use your printer with the parallel port. But if your notebook uses an internal hard disk which is controlled via a "hard disk controller'' that also uses SCSI technology, both the card-slot and the parallel port options may prove troublesome, because most PCs are set up to recognise only one SCSI controller at once - and adding a second controller (such as a PCMCIA SCSI card or a parallel to SCSI converter) will cause the computer to ignore the CD-rom.

Despite all these options for adding CD-rom drives to notebook computers, it is unlikely that they will soon become a standard part of notebook systems. Notebook computer designers are moving in the other direction on their leading machines, many of which do not even come with floppy disk drives as standard any more. If the price, weight and power consumption of CD-rom drives and the discs that they play can be brought down further, all that could change. That, however, will not happen overnight.