Xerox 550 User Manual

The following table shows the possible cases:
Pre-alignment
(exponents I>
o
o
o
o
Pos tno rma I i za ti on
Scale
Answer
Left
o
o
o
o
Scale
Answer
Right
o
Guard Digit Action
(Guard di
git = O. )
Round on guard digit. <D
o Guard digit left shifted
into low end
of
register.®
o
o
Not possible.
Round on guard
digit. <D
Round on guard digit.<D
Gu.ard digit left shifted
into low end of
register. ®
Not possible.
Notes:
<DIncrement fraction if guard digit ~ 8.
<YContents of guard digit become zero on first
left shift.
Normally, there is no time penalty for the rounding opera-
tion. However, if the intermediate value is . FFFFFF and
the guard digit is 8-F after postnormalization, a right
alignment is done after rounding. (See the example below.)
Example
. FFFFFFF
(intermediate result before rounding)
1.000000
not valid)
.100000 (result after postrounding alignment)
FN Floating normalize:
FN = 0 The results of additions and subtractions are
to be postnormalized. If characteristic under-
flow occurs, if the result is zero, or if more
than two
postnormalization hexadecimal shifts
are required, the settings for FZ and FS de-
termine the resultant action. If none of the
above conditions occurs, the condition code
is set to 0010 if the result is positive, or
to 0001 if the result is negative.
FN = 1 Inhibit postnormalization of the result of ad-
ditions and subtractions. The settings of FZ
76 Floating-Point Arithmetic Instructions
FZ
and FS have no effect on the instruction
operation. If the result is zero, the result
is
set to II true II zero and the condition code
is set to 0000. If the result is positive, the
condition code is set to 0010. If the re-
sult is negative, the condition code is set
to 0001.
Floating zero: (applies only if FN = 0)
FZ = 0
FZ = 1
If
the final result of en addition or subtrac-
tion operation cannot be expressed in normal-
ized form because of the characteristic being
reduced below zero, underflow has occurred,
in which case the result is set equal to II true II
zero and the condition code is set to 1100.
(Exception: if a trap results from significance
checking with FS = 1 and FZ = 0, an under-
flow generated in the process of postnorma 1-
izing is ignored.)
Characteristic underflow causes the basic pro-
cessor to trap to location X'44' with the
contents of the general registers unchanged.
If the result is positive, the condition code
is set to 1110. If the result is negative, the
condition code is set to 1101.
FS Floating significance: (applies only if FN = 0)
FS = 0 Inhibit significance trap. If the result of an
addition or subtraction is zero, the result is
set equal to IItrue" zero, the condition code
is set to 1000, and the basic processor exe-
cutes the next instruction in sequence. If
more than two
hexadecimal places of post-
normalization shifting are required and char-
_.- ... _ ... : ...... :_ •. _...J-._£I_ .... ..J __ .. __ .L ___ •• _ .LL_
........... ICII~II""" VIIY'C'IIIV" uuc~ flUI U\.-\..UI, lilt:::
condition code is set to 1010 if the result is
positive, or to 1001 if the result is negative;
then, the basi c processor executes the next
instruction in sequence. (Exception: if
characteri sti c underflow occurs with FS = 0,
FZ
determines the resultant action. )
FS = 1 The basic processor traps to location X'44' if
more than two
hexadecimal places of post-
normalization shifting are required or if the
result is zero. The condition code is set
to 1000 if the result is zero, to 1010 if the
result is positive, or to 1001 if the result is
negative; however, the contents of the gen-
era I registers are not changed. (Exception:
if a trap resu I ts from characteri sti c underflow
with
FZ = 1, the results of significance test-
ing are ignored. )

Xerox 550 Specifications

General

Monthly Duty Cycle	Up to 300, 000 pages
Connectivity	Ethernet, USB
Print Speed (Color)	Up to 50 ppm
Duplex Printing	Standard
Printer Type	Laser
Supported Operating Systems	Windows, macOS, Linux
Paper Size	A4, Legal, Letter