THE age of portable computing is now well and truly here and the improvements in technology have banished the users' excuse that laptops sacrificed processing power and storage. The second half of last year saw a flood of new machines hitting the market and at the same time the major vendors began a no-holds barred, price war. Following Compaq's decision to try and regain ground worldwide, the company slashed its prices on both desktop and laptop computers. Its competitors then did the same, with Apple announcing new prices with new machines in October. Early in November IBM did the same and rolled out new desktop PCs and two new versions of the ThinkPad notebook computer. So aggressive is the pricing battle that Mr Philip Wong, managing director of AST Asia/Pacific, declared that it will result in the ''survival of the fittest''. But he also believed that sales would be stimulated throughout the region. Notebook computers cost half what they did two years ago. The United States research company, International Data Corp, estimates that by next year, 20 per cent of worldwide computer sales will be portables. In terms of sales for those ''fat'' computer companies, it translates into 3.8 million notebooks. In Japan, where desktop space is at a premium, 26 per cent of all new computer sales are netted by the notebook brigade. What has been noticeable is how commonplace the Intel 486SX processor has become. While Toshiba introduced a 486 machine last year, now most brand names have at least one 486 machine to top their range. AST announced three new 486SL notebooks in November, two colour, one monochrome. At the top of the range is the PowerExec 4/25SL ColourPlus notebook running at 25 megahertz (MHz), hard drive upgradability and AST's recently developed ''intelligent'' power management. The machine has a battery life of up to 6.5 hours with a 60-minute recharge time. It also has two PCMCIA slots for expansion. Several options are offered with this model - a SmartPoint cableless trackball which fits to the front of the keyboard and an alkaline battery pack which can give a user an additional 1.5 hours of computer time. The difference between the ColourPlus model and the 4/25SL Colour is only in the display unit. The more superior machine uses a low power 15 centimetre active matrix display. The prices for the top end 4/25SL ColourPlus system vary with what options are taken but AST has said the recommended retail price for the basic model with 80 megabytes is $39,741, while a ColourPlus 203/W (200 MB hard drive, bundled with Windows 3.1 andthe SmartPoint trackball, comes in at $43,641.