lab notes... some labs such as telepoint would also make a great 494 thesis,
495 thesis, masters thesis, or phd thesis. also good skills for the workplace.
the raging debate about what is a hard disk drive,
and what part is the controller...
host adapter interface versus controller
host adapter typically one of:
- HIPPI = High Performance Parallel Interface;
HPI = High Performance Interconnect, typically used for networking between
supercomputers at 800mbytes/sec or 1600mbytes/sec over a 30 meter
span with copper braided differential conductors (ribbon cable)
or 10km with fiber.
originally designed for high-speed interconnections between
processors. recently extended to connect fast I/O devices as well.
high cost ($80k for 80Gbytes).
used for imaging. video editing, etc..
for use with fast computer,
e.g. dec alpha, or dual processor octane (r12000)
- Fibre Channel
note that a drive controller cache is ok for short bursts, but doesn't help
much for video.
voice coil follows the servo track: tracks the servo track during
heating and cooling of drive.
some drives (e.g. PCMCIA) have constant linear velocity, while most
have constant angular velocity.
with constant angular velocity, it is better to put more data on the outer
(larger) tracks than the inner tracks.
accordingly, CHS is fiction.
difference between hard drives and floppy drives: heads don't touch medium
(platters) in hard drives, but heads touch medium in floppy drives.
some hard drives are (or contain, depending on your point of view)
encoding for disk storage media
Manchester code: A code in which:
Contrast with non-return-to-zero.
- data and clock signals are combined to form a single self-synchronizing
- each encoded bit contains a transition at the midpoint of a bit period,
- the direction of transition determines whether the bit is a "0" or a "1,"
- the first half is the true bit value and the second half is the complement
of the true bit value.
manchester codes are used in enthernet (HDLC frames) in addition to disk drives.
ece385 lab9 hall of fame
a few people have been
asking about imaging, pictures, etc..