HP 3000 III Series Manual page 188

System Microcode
Table 5-2. R-Bus Field Code Definitions (Continued)
1101
1100
SPO
(Sc rat ch P.a dO)
SPI
(Scratch Pad 1)
--~'-~-~-1'--'--'~--1--~'~---~---~'------'-'-------1
I Field I I
Label and Name
I
Code
I
Des cr ipt ion
I
____-_- ._- . . I . _ _ I
.~-_._------------_.
__._---- ._I
I
The l6-bit content of the SPO Reg- I
ister is loaded into the R-Bus Reg-I
i ste r •
I
I
'rhe l6-bit content of the SPI Reg- I
ister is loaded into the R-Bus Reg-
i ste r.
SR
(Sta ck Re gister)
0001 The 3- bit content of the SR
Re
gi st-
er is loaded into R-Bus Register
bits
a
thru
2.
R-Bus Register bits
3
thru 15 become zeros.
UBUS
1110
The l6-bit U-Bus data word is load-
ed into the R-Bus Reg iste r. The U-
Bus data is established by the pre-
ceding microinstruction.
x
(Inde x)
0110 The 16- bit content of the X Reg i st-
er is loaded into the R-Bus Regist-
er.
XC
(X Conditional)
0111 The XC R-Bus field code is used
with indexed memory addressing. If
the index bit of the current in-
struction (CIR bit 4) is zero, the
R-Bus Register is loaded with zer-
os. Othe rw ise, the R-Bus Re gi ste r
is loaded with the l6-bit content
of the X Register.
0010
Z
(Stack Limit)
The l6-bit content of the Z Iegist-
er is loaded into the R-Bus Regist-I
ere
I
_ _ _ _ _ _ _
~
.__- ._- - - - - _ . _ - _ . _ . _ - - - - - - _ . _ ._ _. 1
5-8