THE question has always been a case of when rather than if. Everyone knew Apple Computer would eventually introduce colour versions of its PowerBook and Macintosh Classic products, it was just a matter of finding out when. That question has now been answered as the company unveils colour versions of both products at the MacWorld Exhibition in Tokyo today. Given the cursory glance at the systems reporters in Hongkong were treated to last week, it looks as though Apple is about to score big. Also being unveiled today are a new version of the low-end LC product, the Macintosh LCIII; two new mainstream products marketed under the name Macintosh Centris (formerly the Macintosh II line); and two new Macintosh Quadra products that extend the Macintosh line to a new performance level. But it is the colour version of the Classic which should generate most interest, if only because of its extremely aggressive $10,000 price tag - cheap for a machine configured with four megabytes [MB] of RAM [random access memory] and 80 MB of hard disk storage. According to Apple Far East retail product manager Mr Doug Nelson, in launching a colour Classic, the company was mindful of keeping the product at the affordable end of the market, and making it more expandable. Both goals appear to have been met. The Colour Classic is the same basic shape as the mono version, though it bubbles slightly at the top, making way for the slightly bigger Sony Trinitron monitor. Memory is expandable up to 10 MB, with room for further expansion through a processor-direct slot for an expansion card. The machine also has a slot for a math co-processor and seven ports for peripheral devices. ''We think this is a great story and we fully expect this to become a very hot product for us,'' Mr Nelson said. The colour PowerBook - called the 165c - is based on the mono 180 notebook. Though fairly pricey - a four-MB RAM and 80-MB hard disk version costs US$3,389 - there should be no reason why this colour version should not prove as popular as earlier models. Apple claims there is no performance degradation - having added colour - between the PowerBook 180 and PowerBook 165c. The colour version is marginally heavier (15.4 kg compared with 14.96 kg) and slightly thicker because of the screen. Apple Far East is, perhaps ambitiously, promising immediate availability, apparently having ironed-out the delivery problems it experienced when the first PowerBooks were launched. The new Centris systems, which join the Macintosh II line, bring Motorola's 68040 processor platform to the general-purpose Mac range for the first time. The Centris 610 is a ''pizza box'' style machine up to twice as fast as the Mac IIvx and IIci machines that support multimedia as well as mainstream business applications. The Centris 650 is a powerful general business system, with a 25 MHz 68040 processor, memory expandable to 132 MB and hard disk in 230 MB or 500 MB configurations. A Centris 610 configured with four MB of RAM and 230 MB of disk space is priced in Hongkong at US$2,599, while a Centris 650 configured with eight MB RAM and 500 MB of hard disk is priced at US$4,499. Also launched today is Apple's new - and odd-looking - adjustable keyboard, which actually ''breaks'' down the middle to angle the keys to allow the user's hands to rest at a more natural angle. The products announced today are part of the more than 90 releases Apple is scheduled to make this year - its busiest ever.