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Chapter 49 ½ The HP 9810/20/30 Series 805

the character print mode and restores normal calculator operation.

The keylog feature provides a printed record of all calculator keyboard operations. When the keylog mode is selected each key entered from the keyboard is automatically printed. If the calculator is in keyboard mode, the steps in a certain calculation may be verified. In program mode, the result is a full step-by-step listing of the program entered. With the optional plug-in ROM, mnemonics are printed along with the keycode.

Another feature that simplifies the operator’s interaction with the 9810A is a backstep key. The backstep key decrements the calculator program step counter. It’s helpful in examination of stored programs.

Flexibility through Plug-in ROMs

To one person, his 9810A may be an aid in statistics, to another it may be a purely mathematical or scientific machine, while to a third, it may be a peripheral controller. This changing nature of the 9810A is made possible by the plug-in ROM concept. The implementation of this concept posed a special problem for the machine coding. How can blocks yet to be conceived be slot-independent and still interface readily to the basic calculator?

The solution was to use the Format key to initiate a search through possible ROM block locations. The key following the FMT is compared with a special identifier word in each ROM, and when these codes match, the desired ROM has been found.

Many operations which could not be included in the keyboard directly are also implemented through the FMT key:

1) FMT ­ :

raise the plotter pen and move the coordinates given in the x and y registers.

2) FMT ¯ :

lower the plotter pen and move to the coordinates given in the x and y registers.

3) FMT x®

x¬

load or record data registers using the magnetic card reader.

4) FMT GOTO

load a magnetic card program at location zero, and begin execution at location zero (useful for chain-loading programs).

5) FMT CONTINUE

start the paper tape reader and prepare the calculator to accept information.

There routines are all contained in the basic 9810A,

 

 

Interactive Model 20 Speaks Algebraic Language1

Rex L. James / Francis J. Yockey

In Model 20 of the 9800 Series, or Model 9820A, the emphasis is on using the 9800 technology to provide a highly interactive calculator. Like the 9810A, the 9820A is a ROM-driven minicomputer. Its interactive nature stems mainly from its natural algebraic language and its built-in peripherals—keyboard, printer, and display.

Modularity provides another level of interactiveness by allowing the user to configure the 9820A to fit his application.

The display consists of a single register of sixteen alphanumeric characters. Each character is formed by a seven-row, five-column matrix of light-emitting diodes (LEDs). The printer and keyboard are similar mechanically to those of the 9810A (see box, page 808).

The 9820A’s combination of fast LED display and quiet thermal strip printer allows a program to be run in an interactive mode unattainable before. The hard-copy results on the printer aren’t cluttered with user instructions, since these appear in the LED display. User instructions appear instantaneously in the display; there’s no need to wait for a printout.

When a key is pressed a mnemonic or character appears in the display to give instant visual feedback. The 16 characters are enough so that successive keystrokes can be seen in context. For example, the expression "if the square root of 6 equals A, go to line 17" would require the keystrokes

 

1Hewlett-Packard Journal, vol. 24, December 1972, pp. 8—13.

 

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