RCA Spectra 70 User Manual

Subtract
Unnormalized
(SUR) (SU) (SWR) (SW)
General Description
Format
(RR Short)
(RX Short)
(RR Long)
(RX Long)
Condition Code
Interrupt
Action
Notes
Floating-Point Instructions
• The operand specified by the second address (R
2
or XdB
2
/D
2
)
is sub-
tracted from the operand in the floating-point register specified by the first
address (R
1
). The unnormalized difference is loaded into the register
specified by the first address. The sign and magnitude of the difference
determine
the condition code.
o
7 8 11 12 15
o 7 8 11 12 15 16 19 20
o
7 8 11 12 15
o
7 8 11 12 15 16 19 20
• 0 - result mantissa is zero.
1 -
result mantissa is less than zero.
2 -
result mantissa is greater than zero.
3 -
result exponent overflows.
• Address error:
Addressing (RX format).
Specification.
Significance
error.
Exponent overflow.
31
31
• 1. Subtract Unnormalized differs from Subtract Normalized only in that
the difference is not normalized before it is loaded into the result
register.
2.
Exponent underflow cannot occur.
214

RCA Spectra 70 Specifications

General

Brand	RCA
Model	Spectra 70
Category	Computer Hardware
Language	English