RCA Spectra 70 - Page 39

Is Program Mask Bit
Set (1)?
No
Yes
Cancel the Interrupt and Proceed
with Next Instruction
Yes
1.
3.
4.
5.
6.
9.
One of Four
Program Interrupts?
No
Set Bit in the Interrupt
Flag Register
Is Corresponding Bit Set
(1) in Interrupt Mask
Register?
Yes
Store ILC, CC, and Program
Mask in P Counter of
Terminated State
Is it Power Failure,
Machine Check Interrupt,
or Scratch Pad Memory
parity error (if applicable)?
No
Initiate P3, Reset Flag in
Interrupt Flag Register
7.
8.
10. ~==~~==~---1
Extract CC and Program Mask
from P Counter of Initiated
State
Figure 3. Functional Logic of Automatic Interrupt
30
No
Program Interrupt
Hold Interrupt Pending
and Continue at Next
Instruction
Yes
Initiate P 4, Reset Flag in
Interrupt Flag Register
If the Interrupt is a
Machine Check Set the
Program Indicators in the
ISP of P4 (70/45-55 Only)