Questions tagged [interrupt]
For questions regarding processor interrupt signals on retrocomputing hardware
6
questions
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What are uses of the byte after BRK instruction on 6502?
The BRK instruction on the MOS 6502 seems to be one of the more
ill-documented features of the processor. The 1976 preliminary data
sheet from MOS indicates that it's a 1-byte instruction using
the &...
19
votes
4answers
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Did the IBM PC use the 8088's NMI line?
As I understand it, the Intel 8088 CPU used in the original IBM PC had two interrupt lines: INTR and NMI. INTR was fed from the Intel 8259 Programmable Interrupt Controller, which handled the IRQs ...
17
votes
1answer
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How does single-stepping on the 8086 interact with internal and external interrupts?
The 1979 version of the 8086 family user's manual is available at different places in the internet, see 1,2,3. It seems there is no newer version available. This manual documents the single-stepping ...
15
votes
7answers
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8086 stack segment and avoiding overflow in interrupts
This is a followup to Could the Intel 8086 CPU have many segments in memory of the same type?
In the event of a hardware interrupt or user interrupt through the INT instruction, was there a risk that ...
14
votes
1answer
671 views
Why didn't Wozniak's interrupts work on the Apple I monitor program?
In his autobiography, Steve Wozniak recounts[1] his difficulty getting interrupts working on the 6502 microprocessor:
The next step was to debug the 256-byte monitor program on the PROMs. I spent ...
11
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1answer
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Timing interrupts on MS-DOS
On the ZX Spectrum, you get an interrupt every frame. As I recall, the operating system uses this to periodically scan the keyboard and probably other things also, but you can have your own routine ...