Outline for May 16, 2008

Reading: Text, §6, 7, 10

1. Greetings and felicitations!
2. Issues
   continued from last lecture
   1. Goals; what should a good process/device interface do?
   2. Device hardware; what does a device look like?
   3. Device interface; how are the devices connected to the computer?
   4. Device drivers; what do the kernel modules interacting with devices look like?
   5. Process interface; how do the processes access devices?
3. Goals
   1. Character code independence
   2. Device independence
   3. Efficiency
   4. Uniform treatment of devices
4. Device Hardware
   1. Disks: platters, tracks, cylinders, sectors, heads, arms; seek, rotational, and transfer latencies
   2. Drums: one head per track; use
   3. Magnetic tapes: nine-track tapes, frames, tape density, records, inter-record gaps, labels, headers, trailers; winding, transfer latencies
   4. Communication lines: simplex, half-duplex, full duplex; baud; protocols; bit stuffing, character stuffing (escapes)
5. Device Interface
   1. Device registers, controllers
   2. Channels, commands, channel programs
   3. Command chaining, data chaining (scatter-gather)
   4. Selector, multiplier channels
6. Device Drivers
   1. Standard interface; upper, lower part