HP 12C Calculator: Operating Modes, Clearing Procedures, and Memory Organization, Notas de estudo de Engenharia Mecânica

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HP 12C Operating Modes and Clearing Procedures

Number representation

Settings and annunciators

Memory organization

How to selectively clear memory contents

HP 12C Operating modes and clearing procedures

Number representation

There are many different settings that allow the user to customize the HP12C according to personal needs.

One of the basic settings is related to number representation. Basic financial operations usually show two decimals of currency, requiring two digits after the radix mark (decimal point), and this is the default representation. The HP12C allows the number of decimal digits of the number in the display to be changed with the following keystroke sequence: f[number key] where [number key] refers to any key from 0 to 9.

Example 1: Calculate 4/7 and show the resulting value with four, six and seven digits after the radix mark.

Solution: The following keystroke sequence can be used:

4 \ 7 z f

Figure 1

f

Figure 2

f

Figure 3

Note that an automatic rounding occurs with the representation of the number, but internally there is always a ten-digit mantissa and a two-digit exponent of ten for each number. If it is necessary to check the mantissa of the number in display:

fX (hold for as long as needed)

Figure 4

HP 12C Operating modes and clearing procedures

Memory Organization

In the HP12C, memory is organized as a set of registers that can hold a valid number representation. All memory available in the HP12C to the user is represented in Figure 8 in terms of registers. Their contents in the figure are their default contents when memory is cleared or when the calculator is first turned on.

n i PV PMT FV

Stack Registers Cash flow N j T R 0 CF 0 N 0 Z (n) R 1 CF 1 N 1 Y (Σx) R 2 CF 2 N 2 X (^) Σ (Σx^2 ) R 3 CF 3 N (^3) (Σy) R 4 CF^4 N^4 L (^) (Σy^2 ) R 5 CF 5 N 5 (Σxy) R 6 CF 6 N 6 R 7 CF 7 N (^7) R 8 CF 8 N (^8) ... ... ... R. 8 CF 18 N (^18) R. 9 CF 19 N (^19) N (^20)

Registers R 0 to R 9 and R. 0 to R. 9 are "general purpose" registers, and they can be accessed either directly by the user or by some internal functions. The shaded area represents the registers that can be automatically converted into program steps. Although registers R 1 to R 6 are general purpose registers as any other, their contents are used by statistical functions. Financial registers n, ¼, $, P and M are used by TVM, Bond, Depreciation and Cash- Flow functions, but can also be used to hold any valid number.

How to selectively clear memory contents

The "master clear" of the HP12C is accomplished when the following sequence is executed:

• with the calculator off, press and hold - ;
• turn the calculator on;
• release -.

Figure 8

Permanently available program steps

HP 12C Operating modes and clearing procedures

If the operation is successful, the display shows:

Figure 9

The HP12C memory contents now match the ones shown in Figure 8.

It is possible to clear specific parts of the HP12C memory with the use of the clearing functions under -CLEAR-, on the keyboard. The different functions included are:

f² clears the contents of registers R 1 to R 6 and the stack registers X, Y, Z and T to 0.00 without changing any other register contents. This allows new statistic summations to be collected.

fÎ If the calculator is in program mode ( PRGM annunciator on), fÎ clears the first eight program steps to (g(00) and frees all registers used by programs for data storage, if any. If the calculator is in normal (run) mode, fÎ only positions the program memory to step # 00.

fG clears the five financial registers n, ¼, $, P and M to zero.

fH clears all registers containing valid numbers to their default contents, as shown in Figure 8. fH does not clear any program instruction, even if they are stored in registers converted to program steps.

fX clears f annunciator and any partial keystroke sequence (:, ?, ?+, g(, :g, etc)