global outsourcing
- This is a preview of the essay.
To view the full text you must login!
SYSTEM'S SOFTWARE LECTURE 1 26 March 2002.
SECTION 1: INTRODUCTION
CPU WORKS MUCH FASTER THAN INPUT OUTPUT DEVICES
Cannot expect cpu to do nothing while waiting for a printer to complete printing one line before giving it another line
Improve efficiency: reduce I/O dependency by
Overlapping I/O with processing.
HOW? Two concepts: 1. Channel and 2. Interrupt
CHANNEL: a hardware sub-system that works independently from the processor to transfer data between peripherals and memory. When transfer is complete and channel is ready to deal with the next data item it generates an INTERRUPT.
INTERRUPT: a processor facility that causes the CPU to:
1. stop executing current instruction sequence,
2. save the content of the Program Counter (PC) on the stack,
3...