Section 18.1
Review Questions
Early History of I/O
  1. What was the earliest operating system called?
answer...
TOS -- Tape Operating System
  1. What speed disparity made multiprogramming profitable?
answer...
input and output devices are tremendously slower than the central processor
  1. What is a port number?
answer...
a short integer that identifies a specific I/O device and is used with an IN or OUT instruction to identify which device the instruction applies to
  1. Are IN and OUT instructions no longer?
answer...
No! The Intel x86 line of processors (including Pentium) still has them.
  1. What is the physical realization of port numbers?
answer...
contact pads which connect the chip to actual peripheral devices
  1. What are some of the nasty complications of real input and output?
answer...
1. data may flow in both directions at almost the same time
2. timing, how to control the device
3. interoperability, how devices from different vendors work smoothly together
4. automatic installation, such as plug 'n' play
  1. What is a dip switch?
answer...
a tiny switch on a board that sets some crucial number in the hardware, usually an id number
  1. How does plug 'n' play work?
answer...
In the old days, you had to configure your system when you added new hardware, which meant that you had to type the characteristics of the hardware into an configuration file (often called a .INI file in DOS or Windows). Now, you simply plug the device into the proper hardware plug and the device announces its presence to the computer, which automatically configures it and creates the .INI files without your intervention. This method usually works, but not always.