Computer link streamlines armchair investing

It was a clear, comfortable day, and William R. Wallace was sitting in a hotel room in front of an IBM personal computer. Mr. Wallace punched in a couple of codes and a secret password, and the computer was on line with Palo Alto, Calif. Several more codes produced a list of stocks he was interested in. As Wallace watched the screen, the cursor blipped the numbers up or down, reflecting changes in stock prices occurring at that very minute.

Wallace selected a stock: It was coded NTR - for Nutrition Systems. He punched in the number of shares he wanted (200), selected his method of payment (cash or margin account), noted where he wanted his stock certificates delivered , entered another password, and executed the transaction.

A minute or so later a message came back telling him he now owned 200 shares of Nutrition Systems.

''As far as I'm concerned,'' Wallace says, ''this is the first real reason for having a home computer. . . You have real financial power here.''

Wallace is understandably enthusiastic. He is marketing director of C. D. Anderson & Co., discount brokers of San Francisco. What he has been demonstrating is a financial service called the Desk Top Broker. For a one-time the software for the system and get access to the data base.

The on-line connection fees range from 40 cents a minute during business hours to 10 cents a minute on nights and weekends, and Wallace says average connection time is less than four minutes. Because the system has to do with personal finance, it is generally considered tax deductible.

Anderson and Trade-Plus, a Palo Alto data organization, developed this system. It is a marriage of the home computer with financial services many people need: stock and bond quotations and the ability to buy or sell; portfolio maintenance; a margin account; and separate cash-management, IRA, and Keough accounts.

This is how the system works: Up-to-the-minute stock-market quotations feed into a Trade-Plus computer in Palo Alto. Customers access the information via General Telephone & Electric's Telenet. Orders shoot through the Trade-Plus computer to C.D. Anderson's wireroom, which executes them.

''The primary market,'' says Trade-Plus marketing director Leonard Schwarz, ''is the busy executive/professional who is not directly in the securities industry and doesn't have time in the day to follow his own private investments. This facility lets him come home, check his personal computer, and place an order whenever he wants - at 11 at night or 2 in the morning or whenever.'' It would be executed during trading hours.

Another important group, says C. Derek Anderson, president of the discount house, ''is the farmer or rancher isolated from the city, at work in the fields most of the day. Since initiating this service in July we've been amazed at the number of farmers and ranchers who have personal computers.''

Mr. Wallace was watching the terminal. The 200 shares of Nutrition Systems were dropping fast. Well, financial control doesn't necessarily mean quick riches. On Wall Street last week the Dow Jones industrial average surpassed its record on Tuesday and continued upward later in the week. The Dow closed the week at 1, 255.69, up 98.07 points.