1) Base of hexadecimal number system? Answer : 16 2) Universal gate in digital logic? Answer : NAND 3) Memory type that is non-volatile? Answer : ROM 4) Basic building block of digital circuits? Answer : Gate 5) Device used for data storage in sequential circuits? Answer : Flip-flop 6) Architecture with shared memory for instructions and data? Answer : von Neumann 7) The smallest unit of data in computing? Answer : Bit 8) Unit that performs arithmetic operations in a CPU? Answer : ALU 9) Memory faster than main memory but smaller in size? Answer : Cache 10) System cycle that includes fetch, decode, and execute? Answer : Instruction 11) Type of circuit where output depends on present input only? Answer : Combinational 12) The binary equivalent of decimal 10? Answer : 1010 13) Memory used for high-speed temporary storage in a CPU? Answer : Register 14) Method of representing negative numbers in binary? Answer : Two's complement 15) Gate that inverts its input signal? Answer : NOT 16)
Performance ( Optional )
* The I/O system is a main factor in overall system performance, and can place heavy loads on other main components of the system ( interrupt handling, process switching, bus contention, memory access and CPU load for device drivers just to name a few. )
* Interrupt handling can be relatively costly ( slow ), which causes programmed I/O to be faster than interrupt driven I/O when the time spent busy waiting is not excessive.
* Network traffic can also loads a heavy load on the system. Consider for example the sequence of events that occur when a single character is typed in a telnet session, as shown in figure( And the fact that a similar group of events must happen in reverse to echo back the character that was typed. ) Sun uses in-kernel threads for the telnet daemon, improving the supportable number of simultaneous telnet sessions from the hundreds to the thousands.
* Rather systems use front-end processors to off-load some of the work of I/O processing from the CPU. For example a terminal concentrator can multiply with hundreds of terminals on a single port on a large computer.
* Several principles can be employed to improve the overall efficiency of I/O processing:
1. Reduce the number of context switches.
2. Reduce the number of times data must be copied.
3. Reduce interrupt frequency, using large transfers, buffering, and polling where
appropriate.
4. Increase concurrency using DMA.
5. Move processing primitives into hardware, allowing their operation to be
concurrent with CPU and bus operations.
6. Balance CPU, memory, bus, and I/O operations, so a bottleneck in one does not idle all the others.
* The development of new I/O algorithms frequently follows a progression from application level code to on-board hardware implementation, as shown in Figure. Lower-level executions are faster and more efficient, but higher-level ones are more adaptable and easier to modify. Hardware-level functionality may also be difficult for higher-level authorities (e.g. the kernel ) to control.
