HP 3000 III Series Manual page 197

System
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7able 5-4. Function Field Code Definitions (Continued)
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I I
Field
I I
I
Label and Name
I
Code
I
Description
I
I I I I
lOR
(lnclusi ve OR)
JMP
(J ump )
JSB
(Jump to Sub-
routine)
MPAD
(Mul tiply-Add)
lalla
01100
00100
11000
The content of the R-Bus Register
is logically inclusively "ored"
with the content of the S-Bus Reg-
ister and the result is placed on
the T-Bus.
The JMP Function field code directs
a micro-jump to the ROM address
(j ump tar get) specified by bi ts 20
thr u 31 of the ROM Outp ut Regi ste r
if the Skip field condition is met
(a condition must be specified).
The R-Bus, Shift, and Special Field
Decoders are disabled and the U-Bus
and T-Bus become the S-Bus Register
content.
The
JSB
Function field code directs
a micro-subroutine jump to the ROM
address speci fied by bi ts
20
thr u
31 of the ROM Output Registe r if
the Skip field code condition is
met. If the condition is met and
the JSB is executed, the Save Reg-
ister is loaded with the address of
the line following the JSB and is
used as a return address at the
sUbroutine end (see Function field
code RSB). During execution of the
JSB, the R-Bus, Shift, and Special
Field Decoders are disabled and the
T-Bus and U-Bus become the S-Bus
Register contents.
The Function field code MPAD per-
forms the add, shift, and test nec-
essary to execute a multiply algo-
rithm. The R-Bus field of the mic-
roinstruction is coded so that ini-
tially the l6-bit multiplicand is
in the R-Bus Register. The S-Bus
field code is UBUS which is initi-
ally all zeros. The SP3-Register
contains the 16-bit mUltiplier.
Both mUltiplier and multiplicand
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