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Discussion in 'General Mac Discussion' started by mgargan1, Sep 14, 2004.
Does anyone know if the Mac uses hardware interrupts or IRQ's, like pc's use?
AFAIK they do not.
No, Macs do not use hardware interrupts. They are one of the many griefs that Mac users have been spared.
A lot of Macs over the years have had interrupt buttons. I think they all have it wired on the logic board, but only some were connected to actual buttons. They're for developer use only and most Mac users remain blissfully unaware.
In terms of Macs I know had them, the Digital Audio PowerMac, and my old SE... it had a little panel that clipped onto a vent that allowed access to interrupt/reset. Pretty cool, truth be told.
Well, not exactly. Macs just don't trouble the user with knowing anything about the hardware interrupts that are going on behind the scenes. So, you don't have to worry about managing IRQs, etc.
Where are you getting this?
We used a PowerPC micro-controller for an assembly programming class and it used hardware interrupts and had several built into the controller itself. I don't know why there wouldn't be hardware interrupts on G4's and G5's. I found a pdf for the g3 talking about hardware interrupts but am too lazy to continue searching. If you look on Motorola's website you can find the reference manuals to the processor you are trying to find out info about.
correct. From a manual setting standpoint. no, the user never has to set anything manually. interrupts are used by the hardware.
Technically speaking, they use interrupts.
In english, they don't. An interrupt is an address in which the computer access the card or device.
Unlike the PC, the Mac has a limit of 2^16 interrupts. and it's allocated by the computer at boot. not the other way around.
Hope this helps,
I don't know what you are trying to say here, but an interrupt is an event that is sent to the processor that will "interrupt" (that's why it is called an interrupt) the current code and run an Interrupt Service Routine that was written for that interrupt. I don't know what the number of ports that a PowerPC chip can handle interrupts through has anything to do with the initial question. Interrupts can be written as software or implemented in hardware. I thought this was the question. Serial ports and A/D converters on the controller interrupt the CPU using hardware. Wasn't this the question or are we talking about something else?
Obviously, you never know the World of MS-DOS. Then you had to wrestle with user-set hardware interrupt requests, aka IRQs. Each device on your system had its own explicitly set IRQ. IRQ 3 might be a modem. IRQ 7 might be a network card. IIRC, there were only sixteen IRQs available. There were so few of them that in some cases you had to use the same IRQ for two devices. Windows 95, or was it 98, made the process a bit more transparent to the user by assigning the IRQs via Plug & Play.
Of course they do! The alternative would be polling, and that would be painful.
Macs have always used something very much like Windows plug-and-play to handle device arbitration. There was never a bus like ISA that required manual configuration, so Mac users were spared that.
The older Apple II series did make one deal with jumpers and DIP switches and all that fun stuff. Also, installing SCSI devices on older Macs often involved frustrating exercises in playing with addresses and terminator resistor packs. These days, however, virtually all expansion hardware uses automatic configuration.