Formats Associated With Code Segments - HP 3000 III Series Manual

System/CPU Overview
Figure 2-6.
CODE SEGMENT TABLE
Doubleword
o
I 1
i
2
i
3
i
4 I I 6 1
7 1 8 1 9 '10
1 11
1 12 1 13 1 14 1
15
5
AIMIRITI
L/4
Reserved
Reserved
I
B
Address
A Absence Bit = 1 if segment is absent from main
memory.
M Mode Bit = 1 if segment executes in Privileged
Mode (Code onlyl.
R Reference Bit ~ 1 if segment has been referenced
(set by microcode).
T Trace Bit = 1 if trace feature is used. Checked by
PCAl instruction.
'L length Field = segment length divided by 4.
B Bank Address. Points to memory bank (if resident
in l'lIain memory) in which segment resides.
ADDRESS
Absolute address of PB within B if the
segment is present. otherwise the 3rd
and 4th words contain the absolute
disc address.
SEGMENT TRANSFER TABLE
Words
STT length
011
2 31 4 5
61 7
8
91 10 11 12113 14 15
OIUlo
0
0
0 0
01
LENGTH
U Uncallable bit
LENGTH Maximum = 255 (Calls from external
segments may reference only the first 127
entries. Pl-1 thru PL-127.HPL.Q= STTL.)
local Program label
011
2 31 4 5
61
7
8
91 10 11 12113 14 15
01
u
I
ADDRESS
U Uncallable bit
ADDRESS PB relative, + only
External Program label
011
2
31 4
5
61
7
8
91 10 11 12 1 13 14 15
11
STT #
I
SEG#
STT# STT entry number in target segment,
maximum
=
127
SEG # Target segment
STATUS
Word
011
2 31 4 5
61
7
8 9110 11 12113 14 15
I
M
I
I
I
T
I
A
I
0
I
c
I
cc
I
SEGMENT #
M Mode bit (=1 for privileged mode)
I Interrupt enable (1 )/disable(OI. external
T
Traps enable( 11/disable(OI. user
R Right Stack Opcode bit (pending = 11
0 Overflow bit
C
Carry bit
CC
Condition
Code
SEGMENT # currently executing
90020-7
Formats Associated With Code Segments
2-18