PAK-II Datasheet, PDF (8/28 Pages) List of Unclassifed Manufacturers – 310 Ivy Glen Court

• RREG – Temporary storage registers (0-23)
• DIRS – Byte indicating port directions (0=input, 1=output)
• IBYTE, OBYTE – Input or output byte
• Using the alternate form of a command prevents it from returning the
status result.
Floating Point Numbers and Errors
The 32-bit floating point representation used by
the Pak II is a modified version of the IEEE754
format. The first byte is the exponent (biased by
127). If the exponent is zero, the number is zero.
The second byte contains the most significant bits
of the mantissa. The most-significant bit is the sign
bit (1 is negative) and the mantissa starts with an
implied 1 before the decimal point. The next two
bytes are the remainder of the mantissa.
This differs from the IEEE745 format (the one
used by PC C compilers, for example) only
slightly. In the IEEE745 format, the sign is in the
most-significant bit of the exponent. The most-
significant bit of the first byte is actually the least
significant bit of the exponent. Otherwise, the two
formats are identical. The Pak II has functions to
convert back and forth between the two formats.
The accompanying disk contains a Windows
program (fconvert.exe) that will convert between a
normal floating point number, the Pak II's format,
and the IEEE745 format. Simply enter the number
you know and the program will display the other
two formats.