Motorola MVME162 manual Packed Decimal Real, Scientific Notation

Floating Point Support

Packed Decimal Real

This format would appear in memory as:

4-bit sign field	(4 binary digits)
16-bit exponent field	(4 hex digits)
68-bit mantissa field	(17 hex digits)

A packed decimal number takes 12 bytes in memory.

4

Scientific Notation

This format provides a convenient way to enter and display a floating point decimal number. Internally, the number is assembled into a packed decimal number and then converted into a number of the specified data type.

Entering data in this format requires the following fields:

An optional sign bit (+ or -).

One decimal digit followed by a decimal point.

Up to 17 decimal digits (at least one must be entered).

An optional Exponent field that consists of:

An optional underscore.

The Exponent field identifier, letter "E".

An optional Exponent sign (+, -).

From 1 to 3 decimal digits.

For more information about the MC68040 floating point unit, refer to the M68040 Microprocessor User’s Manual.

MVME162IG/D2 4-19