RONALD Reagan doesn't have a computer terminal in the Oval Office. The high technology that so interests China, where he is now traveling, has yet to find a place on the presidential desk.
With the growing and enthusiastic use of computers in the White House, however, it's just a matter of time before a president of the United States uses his own word processor.
President Reagan's aides are slightly scornful of the state of technology in the Carter White House.
''When I came here in 1980, the office had a telephone and a typewriter 200 years old!'' says Craig L. Fuller, assistant to the President for Cabinet affairs. ''There were hardly any word processors - a dozen or so were stored, but they didn't want to use them.''
''We were shocked to find out how outdated and inefficient the operation was, '' says John W.F. Rogers, special assistant to the President for administration. ''You would have thought they would be at the cutting edge of technology. Yet it got little attention.''
The Carter White House did begin to look at automated systems for operations other than payroll, these officials say. But there were only about 15 word-processing machines on hand, and only limited computer tracking of correspondence, block grants, gifts, and the like.
''Most functions existed in manual form, on 3-by-5 cards,'' Mr. Rogers says. ''The Carter people were the first into the new technology. We seized on their beginning and accelerated it dramatically.''
Today the White House, catching up with other parts of the executive branch of government that make heavy use of computers, is on its way to technological sophistication. The accounting system has been automated. About 150 IBM Display Writers have been installed throughout its offices for clerical personnel.
Moving from bottom to top in the White House hierarchy, there are also three ''executive work stations'' using a modified X-T model of the hard-disk IBM. Linked with a main-frame computer, these machines can call up financial, personnel, and other information to facilitate management tasks. They also connect with an outside commercial data base in order to communicate with other federal agencies and departments. Ultimately there are plans for 40 such stations.
''What has happened here in the last three years is a revolution,'' Rogers says, ''although we're still far short of our goal.'' About $1.2 million has been invested in White House automation in the past three years, he adds.
Introduction of the computers has vastly reduced paper work. With electronic-mail capability, selected offices in the White House can now move presidential speeches and policy information electronically to more than 20 federal departments and agencies, and receive information back.
''It allows us to get our message instantaneously all over town,'' Mr. Fuller says. ''It doesn't mean policy is different, but it ensures that the President will get the views of his departments and agencies in a more timely manner. That helps reinforce the Cabinet system of government.''
Computers have proved useful on the road, too, he adds. ''We travel with a portable electronic-mail unit - the Radio Shack 100 - so we read messages quickly from any point of the world.''
Administrative as well as some policy tasks are performed with the new technology: drafting and editing speeches, processing correspondence (about 5, 000 to 7,000 letters a day are received at the White House), sending messages, scheduling meetings, tracking legislation and Cabinet issues, working out color graphics for presidential budget briefings, supplying letter-perfect correspondence to the President.
''We're only at the intermediate state of automating manual functions, especially at the secretarial and clerical level,'' says Rogers, who used to be administrator with the American Enterprise Institute. ''But we will move into the policy area and the use of executive work stations by the senior staff members. We built the foundation, and the frame of the house is up. Now we have to get to the roof and think about moving the furniture in.''
Still to be designed is how information will flow, to whom it will flow, how internal and external security risks will be safeguarded.
Political scientists are fascinated by how a vast store of information at the President's disposal can aid in policymaking and enhance executive power and effectiveness. Already, the availability through computers of an array of wire services and outside data bases makes it possible for White House planners to determine, say, what is going on in a city to which the President is traveling. Such information can prove helpful in everything from writing speeches to scheduling political events.
White House computers now keep track of how key news stories are being covered. Mr. Fuller recounts, for instance, how a story by United Press International on telephone access charges reported the administration position incorrectly. Since Fuller monitors anything on access charges, the computer put the item in his electronic mailbox. ''I saw that I had mail, read the story, saw the mistake, and called (White House press spokesman Larry) Speakes,'' he says. ''He contacted UPI and they corrected the story.''
The computer center serving the entire Executive Office of the President (EOP), of which the White House is only a part, has also been upgraded. Situated in the New Executive Building, this tightly secured facility (known as EOPCC) has doubled in size, with a capacity four times what it was three years ago. Its soundproof rooms contain 10 major computer systems, including two highly advanced IBM 3083s and one IBM 4341 for a total 48 million bytes of memory; a Xerox 9700 laser-beam printer that turns out two pages per second; and a bank of consoles to monitor what is going on in the computers.
About 60 percent of the EOPCC's work is for the White House Office of Management and Budget (OMB), officials say, and the center's operations continue to expand. In fiscal 1984, $8.3 million was budgeted for central operations and software development. The proposed new budget calls for an expenditure of $9.1 million.
''People don't realize how much the White House has modernized,'' says Thomas K. Lewis Jr., director of the Automated Systems Division in the Office of Administration. ''Until a few months ago, (OMB Director David) Stockman used to have a graphic artist to prepare the charts for the budget. Now there's complete color graphic support on the computer - producing line charts, bar charts, and pie charts for OMB.''
Looking to the future, White House officials say they are trying to design the kind of computer system that can be built upon to serve successive administrations. ''We have to think about what makes sense institutionally,'' says Rogers, a young man with a sense of excitement about what he is doing, ''so when I leave, the plan will be in effect and will serve every president.''