HP 3000 III Series Manual page 191

System Microcode
Table 5-3. S-Bus Field Code Definitions (Continued)
I - ~
1
1 1
Fie ld
I
Label and Name
1
Code
1 1
PCLK 01011
(Process Clock)
"---.1
1
Description
1
~--
I
1
The l6-bit content of the PCLK Reg-
register is placed in the S-Bus
Regi ste r.
Q
( S
ta c
k Ma
r
k
e r
Pointer)
QDWN
(Stack Marker
Poi nte r Down)
RA
RB
RBR
(Read Bank
Register)
RC
RD
SBUS
10001
01000
11011
11010
00011
11001
11000
01111
The l6-bit content of the Q Regis-
is loaded into the S-Bus Register.
The QDWN S-Bus field code is used
to put the content of the lowest
valid TOS register in the S-Bus
Re g is te r • Re fe r top a r a
5-
6 •
The register named RA by the Namer
Re g is te r is pIa ce din the S-B us
Register.* Refer to para 2-96 and
5-2.
The register named
RB
by the Namer
Register is placed in the S-Bus
Register.* Refer to para 2-96 and
5-2.
Read Bank :Register onto S-Bus (12:
15).
The S-Bus bits 0 -
11
are
zeroed. The Ba nk Reg iste r to be
read is specified in the MCU field.
Execution of the Special field is
inh ib i ted.
The register named RC by the Namer
Regi ste r is placed in the S-Bus
Register.* Refer to para 2-96 and
5-2.
The register named RD by the Namer
Register is placed in the S-Bus
Register.* Refer to para 2-96 and
5-2.
The SBUS code causes the S-Bus Reg-
ister content to remain unchanged.
- . - - - - - - ~ - - - -
_.__._-
- . - - - - ~ - - - - ~ - - - - -
---I
*True only if RA:RD are being used as part of the Stack. RA:RD
1
are often used by the microprogram as scratch pad registers
1
when not used otherwise.
1
1
5-11