PDP-10 (36-bit Words)

Note: The PDP-10 is the same machine as the DEC-10.

Single Precision (one 36-bit word) floating point:
 

PDP-10 floating point single precision:
0
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 11 12 13
 14 15
 16
 17 18 19
 20
 21
 22
 23
 24
 25
 26
 27 28
 29
 30
 31
 32 33
 34
 35
Sign Bit Exponent (bias: 12810) Fraction: bit 9 is the most significant

Double Precision (two 36-bit words) floating point:
Double Precision (72 bits): First 36-bit Word:
0
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 11 12 13
 14 15
 16 17 18 19
 20 21
 22 23
 24
 25
 26
 27 28
 29
 30 31
 32 33
 34
 35
Sign Bit Exponent (bias: 102410) Fraction (First, most significant part): bit 12 is the most significant

 

Double Precision (72 bits): Second 36-bit Word:
0
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 11 12 13
 14 15
 16 17 18 19
 20 21 22 23 24 25
 26
 27 28
 29
 30
 31
 32 33
 34
 35
Ignored Fraction (Second, less significant part): bit 1 is the most significant bit in this word

EXPONENT (E): To the base 2, with a bias in the single precision floating point of 128 decimal (200 octal), and in the double precision floating point of 1024 decimal (2000 octal).

FRACTION: Has no hidden bit.

NEGATIVES (In the Fraction): Twos complement.

The value of the number N is N = F x 2E-128 (Single precision), or N = F x 2E-1024 (double precision) where F is a binary fraction such that 0 <= |F| <1

INTEGERS: 2's complement.-34,359,738,368 to +34,359,738,367