17 May
2001
17 May
'01
2:15 p.m.
"Hans Franke" <Hans.Franke(a)mch20.sbs.de> said:
Well, as long as you think along a 'real' drum
with flying heads
etc. you're right, but there is a simple solution - take a card
board tube and warp regular cassete tape around, and let a head
read/write this tape ... if you take an old style washing powder
drum (ca. 30 cm diameter / 1 ft) you get a lenght of about 1m
(3 ft 4") - what was the usual speed of cassetes ? 4 cm/s ? I'm
not shure (Tony ?), as a rough estimation you get a track size
of some 3 kByte and an average access time of 12s not to bad ...
I have this really sick and perverted habit of picking up
unusual items just in case they might be useful for future
projects. All of this talk about building a drum storage
reminded me of something that I added to my eclectic resource
pile a few years ago, an old drum type fax machine.
But, when it comes to adding mass storage to a digital
computer system, IMHO I can't think of anything faster,
easier, or more reliable than the old Commodore 1541.
* The DOS is built-in.
* Only the system side communication routines need to be
written and there is commented source code to use as
examples.
* The drive side communication routines can also be
rewritten.
* Since the communication with the drive is normally
handled with very robust handshaking, the speed of the
computer system is totally unimportant. This also means
that disk I/O can be easily interrupted.
* And additional drives can be daisy-chained on the same
bus.
Regards,
--Doug
=========================================
Doug Coward
@ home in Poulsbo, WA
Analog Computer Online Museum and History Center
http://www.best.com/~dcoward/analog
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