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With tbe length code split into two 4
bit fields, the maximum length of arith-
metic variable length operands is
16
bytes.
The effective length of variable
length fields is one more than the
length code.
REVIEW QUESTIONS eN SYSTEM/360
INSTRUCTIONS
1.
Instructions are a multiple
of
in length.
2.
Instruction addresses must be divi-
sible by ____ or a __
~
____ __
exception will occur.
3.
The first byte of every instruction
is tbe
4.
For the following Op Codes (in
hexadecimal code), indicate the
binary bit structure of the Op Code
and its length in halfwords.
Op Code
Einary
Length
a.
lA
b.
56
c.
9C
d.
FD
5.
All effective storage addresses are
generated by adding a 12 bit
to
a 24 bit
in one of the
general registers.
6.
Some effective storage addresses
are generated by also including a
(n)
factor in one of the gener-
al registers.
7.
Address generation (does/does not)
change the contents of the general
registers or the instruction in
storage.
8.
A program can be relocated in stor-
age by changing the contents of
the _______ __
9.
The displacement has a range of 0
to
bytes.
10.
Only general
registers
to
can be used as
Ease or index registers.
11.
What happens if register 0 is spec-
ified as a base or index register?
12.
Label the fields' of the following
formats.
r--T--T-'
a.
RR
I
I
I
I
L __
J. __ .L-_J
r--T--T~--T--'
b.
RX
I
I
I
I
I
I
L __
J. __ J._-.L __ J. __ J
'--T--~T--T--~'
c.
RS
I
I
I
I
I
I
I
L __
J. __ J._-.L __ J. __ J. __ J
r--y-----y--T--y--'
d.
SI
I
I
I
t
I
I
L __
J. _____ J. __ J. __ J. __ J
,--T--T--y--T--T--T----'
e.
SS
I
I
I
I
I
I
I
I
L __
.L-_.L-_J.~_.L__.L-_J.
____ J
13.
For most operations, the
r~sults
.replace the pst/2nd) operand.
14.
Given the following RR type
instruction:
r-------T---y---,
I
ADD
I
7
I
4
I
L _______
J.---J.---J
The result of .the addition will
replace the contents of register ____ _
15.
In the SI format, the 2nd operand
is located in
and is
one ___ long.
16.
Only the
format uses an index
register for address generation.
17.
Only the ___ format involves varia-
ble length data.
18.
What is the relaticnship between
the number in the length code of
the SS format and the number of
bytes in the data field?
INSTRUCTION SEQUENCING AND BRANCHING
•
•
•
Unless otherwise specified, instruc-
tions are handled sequentially.
Instructions are divided into two
parts:
Op Code and address.
Instructions are fetched from main
storage during I-time and executed
during E-time.
1-43
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