IBM upgrades its Personal Computer

The International Business Machines Corporation unveiled a new personal computer here Tuesday. But unless you looked closely, you couldn't tell the difference between the new model - the IBM Personal Computer XT - and the other model, the IBM PC.

The new model has the same, familiar keyboard found on the PC. There are no flashy design changes to conjure up a new image for the company. The XT seems to be just like the PC - but with two major differences. It has about nine times the memory of the PC, and it can communicate with PCs and large IBM mainframe computers.

But even with these changes, IBM can introduce the XT without the big-band pizazz, some computer experts say. ''This is a deliberate upgrading step,'' says William Ablondi, vice-president of market analysis at Future Computing Inc. ''You wouldn't expect something earthshakingly flashy coming out of IBM. They want to build up confidence'' in their personal computer line, he says. Future Computing, in Richardson, Texas, tracks the personal computer industry.

Although the IBM XT is not as powerful, as fast, or as completely different as Apple's new Lisa, which was introduced in January, ''that's not the point,'' Mr. Ablondi says. ''They aren't forgetting Lisa, but they are going after their existing base of customers. It makes all the sense in the world.''

Mr. Ablondi says that with all the IBM mainframe computers being used by businesses, and with the new communication and memory of the XT, there will be a demand for the new computer. People will use the XT to get information from the large IBM mainframes, transfer it from PCs they may already own, or both.

The main new feature of the XT is a built-in, hard-disk drive. Hard disks can store more information than popular, less expensive floppy disks. The new XT hard-disk drive can store about 10 million characters of information, which roughly equals 5,000 double-spaced, typewritten pages. A user could increase this capability by buying another new IBM product, a memory expansion unit ($2, 695), which would boost storage capacity to 22 million characters.

''This is a quick fix, a temporary fix,'' says Chris Christiansen, an analyst who follows business computers for the Yankee Group in Boston. ''It probably addresses the huge number of users that want hard-disk storage but weren't able to get it from IBM before. It also allows a large amount of memory so they can take advantage of (some of the newer software on the market,)'' he says.

Mr. Christiansen says ''this is an intermediate step to something else.'' It's not really a new product, he says, but an enhancement. He views it as a steppingstone to a much more powerful, faster personal computer which IBM probably has waiting in the wings for introduction later this year.

This idea of ''enhancement'' stems from a number of things. First, the new computer still uses the same microprocessor that the IBM PC uses. The microprocessor is the ''thinking'' part of the computer, which controls all the other parts. Second, the computer is available at IBM Product Centers today (March 9) - there's no introduction and promotion buildup trying to create demand months in advance of the product. Third, the company says it has not targeted any special market for the XT. ''We have no target market for the XT,'' says Rex Reed, district manager of dealer accounts at IBM. ''It will be the same market as the PC. We are taking advantage of extended capabilities.''

To help expand the entire personal computer market for the two IBM products, the company has moved aggressively in price. It has just reduced the price of its PCs by 15 percent and introduced the new product for $4,995. It has also introduced some new software products. One of them is called PeachText, an improved word processing program from Peachtree Software.

Will the PCs be slowly phased out? ''It depends,'' says Joseph Potts, IBM's manager of PC systems support. ''It's a cost/production question.'' Adds Future Computing's Ablondi, ''The way things move in this industry, everything's temporary.''