Xerox 550 - The Bas I C Processor

FAST MEMORY
ARITHMETIC AND CONTROL UNIT
GENERAL REGISTER BLOCK (TYPICAL)
INSTRUCTION REGISTER
ol~ ______________ ~
1 I.I:::::::.:::::}:=:::······ ':):::::fff::::rrttr::::t:ttt···:::::\::tt::tl
2 1:=:::"::::::::::':: :::::::r:t:::::ttI:::::I:::t:::::::I:::.::I:}::::·::::::::t:':::I:I::i'::::::]
3 1'.::I::::::::::r:::::::=:,: .::::f:::Im:tt:::fIttt::\:t:II:t:::::::!::::'j':·::II!::::::!::1
4 II:::::.:::::--::::::::!:}f::: :tI:·:,:::::::!::=::::::·,!:::!:!:::':::'I:\::I::.:.:!!:.: .. :.:::::: .• : •• !:.::::::.]
7 I i:::.::::i:.:::·''):;:::::.::'::i:::::i:::::::::·:::::::::: ::::?:ff.?::ftt:·::::::::::::f:::D::::ul.
8~1 ______________ ~
9~1 ______________ ~
10~1 ________________ ~
11 ~I ________________ ~
12 ~I ________________ ~
13~1 ________________ ~
14 '-' _________ ~
15
16
17 I~ _________ ......
18 '-I ________________ ~
191 ~ _______________ .....
20 ~I _______________ .....
211 ~ ______________ .....
I I
10 Basic Processor
Index
Registers
o Indirect Access Flag
o
III II II I Operation Code Field
1 7
[]]]J General Register Designator
8 11
ITO Index Register Designator
12 14
Reference Address Field
IIII1111111111111111
15 31
....... -- .....
Memory
•
Reserved
I/O Processors I
• r
I
Read/Write Direct
• r
•
Interrupts
tv\apping
• r
• Access Protecti on •
PROGRAM STATUS WORDS
[[OJ Condition Code
o 3
ITO Floating-point Mode Control
5 7
o Master/Slave Mode Control
8
o Memory Map Control
9
OJ Arithmetic Trap Masks
1011
Instruction
Id I III I II I I I II I I I I !ddress
15 31 Extended
om Write Key
32 35
[[IJ Interrupt Inhibits
37 39
OJ Register Block Pointer
5859
o Register Altered
60
o Mode Altered Control
61
Displacement
Figure 2. The Basic Processor