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Quiz based on Digital Principles and Computer Organization

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)...

Disk structure

Disk Structure

* The conventional head-sector-cylinder, HSC numbers are mapped to linear block addresses by numbering the first sector on the first head on the surface track as sector 0. Numbering begins with the rest of the sectors on that same track, and then the remaining of the tracks on the same cylinder before starting through the remaining of the cylinders to the center of the disk. In modern practice these linear block addresses are used in place of the HSC numbers for a various easons:
1. The rectilinear length of tracks near the surface of the disk is much longer than for those tracks placed near the center, and therefore it is possible to compress many more sectors onto surface than onto internal ones.
2. All disks have some bad sectors, and therefore disks continue a few extra sectors that can be used in place of the bad ones. The mapping of extra sectors to bad sectors in controlled central to the disk controller.
3. Modern hard drives has thousands of cylinders, and hundreds of sectors per 
track on their outermost tracks. These numbers restrict the range of HSC numbers for many (older) operating systems, and therefore disks can be aligned for any suitable combination of HSC values that falls within the complete number of sectors physically on the drive.
* There is a restriction to how closely grouped individual bits can be placed on a physical media, but that limit is growing increasingly more grouped as technological advances are made.
* Modern disks group many more sectors into outer cylinders than inner ones, using one of two approaches:
• With sustained Linear Velocity, CLV, the density of bits is same from cylinder to cylinder. Because there are more sectors in external cylinders, the disk spins slower when reading those cylinders, causing the rate of bits passing under the read-write head to remain constant. This is the method used by modern CDs and DVDs.
• With sustained Angular Velocity, CAV, the disk rotates at a sustained angular speed, with the bit density reducing on outer cylinders. (These disks would have 
a constant number of sectors for each track on all cylinders.)

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