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Topic: Drum memory

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History of computing hardware

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	Drum memory - Wikipedia, the free encyclopedia
		Drum memory was an early form of computer memory that was widely used in the 1950s and into the 1960s.
		Drums were later replaced by core memory, which was faster and had no moving parts, and which lasted until semiconductor memory entered the scene.
		A drum is a large metal cylinder that is coated on the outside surface with a ferromagnetic recording material.
	en.wikipedia.org /wiki/Drum_memory (401 words)

	Random access memory - Wikipedia, the free encyclopedia
		This is in contrast to sequential memory devices such as magnetic tapes, discs and drums, in which the mechanical movement of the storage medium forces the computer to access data in a fixed order.
		One defining characteristic of RAM is that its accesses to different memory locations are almost always completed at about the same speed, in contrast to some other technologies that required a certain delay time for a bit or byte to “come around”.
		Core memory, which used wires attached to small ferrite electromagnetic cores, also had roughly equal access time (the term “core” is still used by some programmers to describe the RAM at the heart of a computer).
	en.wikipedia.org /wiki/Random_access_memory (1009 words)

	Mos shift register compensation system for defective tracks of drum storage system - Patent 4016547
		Solid state memory circuit 10 of the instant invention ensures that the full capability of this particular rotating drum memory is retained although modifications to this circuit within the scope of one skilled in the art can be made to accommodate other drum memories.
		Should the drum memory track generating the clock pulses which are normally fed to the shift registers via lead 11a become damaged, a crystal clock oscillator 20 is included to compensate for the loss of this function.
		Drum memory 11 provides data signals schematically depicted as passing on a lead 11' and clocking signals are fed via a lead 11".
	www.freepatentsonline.com /4016547.html (2113 words)

	drum on Encyclopedia.com
		The variety of tone and the volume of sound from a drum depend on the area, tension, and material of the membrane that is struck and, more particularly, on the skill of the player.
		The snare drum (sometimes called the side drum) also has a drumhead at either end; across one end are stretched gut strings wound with wire.
		Magnetic Drum Memory This magnetic drum unit was the memory in the IBM 650 computer, introduced in 1954.
	www.encyclopedia.com /html/d1/drum-mus.asp (826 words)

	Drum memory - LinuxQuestions.org Wiki
		Drum memory was a form of computer memory used during the Bronze Age of computing.
		Drum memory was, to a certain extent, sequential, rather than random, like today's modern RAM, in that you had to wait for the section with your data to pass under the read/write head.
		Drum memory was eventually replaced by core memory when manufactoring of core was sent overseas.
	wiki.linuxquestions.org /wiki/Drum_memory (179 words)

	Introduction to System Software, Chapter 11
		Drums were introduced in 1952 on the Whirlwind I computer; by 1961, the Manchester University Atlas computer was using a primitive file system which blurred the distinction between drum and tape.
		Drum memories had, as their central element, a rotating drum coated with a continuous layer of magnetic material The drum was driven by an electric motor, spinning at a fixed rate, typically from 5 to 60 revolutions per second; the rate was typically locked to the frequency of the alternating current powering the motor.
		The logical characteristics of the drum are the number of heads and tracks (these numbers are the same), the data capacity of each track, and the speed at which the drum rotates, which determines the time to read and write a track or the time to find and read part of a track.
	www.cs.uiowa.edu /~jones/syssoft/fall00/notes/11disk.html (8042 words)

	Unisys History Newsletter v3n3 (Site not responding. Last check: 2007-11-07)
		ERA was more familiar with drum memory technology, and in fact had done design studies for IBM and NBS in 1949-1950 for drum memory computers, neither of which was built.
		The drum memory was 8.5 inches in diameter, rotated at 3500 rpm, and held 16,384 24-bit words.
		The drum was, of course, constantly rotating while the processor was executing each instruction, so that there was no guarantee that the read-write head would be positioned at the next instruction when execution of the previous one was completed.
	www.cc.gatech.edu /gvu/people/randy.carpenter/folklore/v3n3.html (2352 words)

	Doug's Forum - Vacuum Tube Computer and Drum Memory
		A drum memory was a big cylinder, similar to Edison's original phonograph cylinder, with a ferrous coating.
		There were mounting bars around the cylinder and each mounting bar had many read/write heads on them (10 or 20 or so), and they were carefully staggered so each head read and wrote to one circular track on the cylinder without interfering with it's neighboring head.
		The main difference was the memory, a 704 used a core memory.
	www.dougscode.com /forum4/topic.asp?TOPIC_ID=15 (346 words)

	Intro to System Software, Chapter 11
		The oldest random-access secondary storage device is the magnetic drum memory, although it is worth noting that some early computers actually used drum technology for their primary memory.
		Drums were introduced in the early 1950's and were obsolete by the late 1960's.
		For example, in the 1970's, when core memory was still common as the primary memory of large computers, typically with sizes under one megabyte, bulk core memory was used as secondary memory in sizes up to about 16 megabytes.
	www.cs.uiowa.edu /~jones/syssoft/notes/11disk.html (9702 words)

	IBM Archives: 650 RAMAC fact sheet 1959
		Up to four RAMAC memory units may be used in a RAMAC 650 system, giving it a random access memory of as many as 48 million digits.
		In it is a magnetic drum memory unit in the form of a cobalt-nickel plated metal cylinder which revolves at 12,500 RPM.
		The average access time to data or instructions on the magnetic drum memory is 2.4 milliseconds -- 2.4 thousandths of a second.
	www-1.ibm.com /ibm/history/exhibits/650/650_tr2.html (1618 words)

	WPS:LGP 21:Software
		Read-record heads, which are for magnetizing and for detecting magnetization on the drum, are mounted in a frame around the drum.
		The use of 64 tracks and 64 read-record heads means that any given portion of the drum is available to a read-record head at least 64 times faster than if the memory consisted of a tape governed by one read-record head.
		Notes: If the number in memory location is of the same sign as the number in the accumulator, the result of subtraction is a number smaller in absolute value than the larger of the two numbers.
	www.wps.com /projects/LGP-21/Software/lgp-30-man.html (14388 words)

	Dans Music Shop - Yamaha DSXT10 Drum Kit
		This powerful system can be used in conjunction with either our newly designed drum pads -utilizing real drum heads for a totally natural feel- or drum pads like the TP80S, etc. or trigger pickups such as the DT 10/20, etc.
		All drum wave data has been re-sampled at a higher resolution and YAMAHA acoustic drum sounds such as the Maple Custom, Recording Custom, etc. have been added offering the richest, most expensive sound quality possible.
		Drum kit, chain, song and system data can be both transmitted and received via MIDI bulk dump and parameter changes are received as well.
	www.dansmusic.flyer.co.uk /DTXTREMEWEBPAGE.htm (649 words)

	[No title]
		A percussion instrument consisting of a hollow cylinder or hemisphere with a membrane stretched tightly over one or both ends, played by beating with the hands or sticks.
		Something resembling a drum in shape or structure, especially a barrellike metal container or a metal cylinder wound with cable, wire, or heavy rope.
		Any of various marine and freshwater fishes of the family Sciaenidae that make a drumming sound.
	www.homoexcelsior.com /omega.db/datum/computer_science/drum (105 words)

	Home Recording dot com BBS - drum machine memory is maxed out , what to do ? (Site not responding. Last check: 2007-11-07)
		Now i could record the drum tracks down to cdr or mini disk, then earse all the memory and write 2 or 3 more songs.
		back and turn up/down say snare or cymbols etc i whould not be able or change the sound of a purticular drum.
		I think it is usually the opposite on most drum machines.
	homerecording.com /bbs/showthread.php?t=46959 (477 words)

	Drum memory : Magnetic drum (Site not responding. Last check: 2007-11-07)
		For many machines a drum formed the main working memory of the machine, with data and programs being loaded onto or off the drum using media like paper tape or punch cards.
		Drums were later replaced by core memory, which was even faster and had no moving parts.
		It uses material from the wikipedia article Drum memory : Magnetic drum.
	www.eurofreehost.com /ma/Magnetic_drum.html (423 words)

	[No title]
		Patch memory is not cleared when the device is closed, however, so a subsequent call to cache patches with _exactly_ the same PATCHARRAY does not cause the driver to clear memory and reload the patches.
		What is implied is that, using the standard cache patch messages, drum patch memory can be cleared and reloaded without affecting melodic patch memory, but not vice versa.
		The type of app that would benefit from their use would be one that wants a drum set always present, and relatively static, and expects most patch changes to be melodic.
	ftp.gravis.com /Public/sdk/GTEK19.TXT (1008 words)

	[No title] (Site not responding. Last check: 2007-11-07)
		We were briefly involved, thirty years ago, with work on a memory exploiting a "Moving Barkhausen Discontinuity." As I recall, it's possible to create a detectable blip in a skinny piece of wire at a point where two magnetic states meet...and then electrically push that blip along the wire past a detector.
		A drum memory has to spin fast and very evenly with as little wobble or variation in radius as possible, with a recording medium deposited very evenly all over the surface.
		The disadvantage of drums, of course, was that you got a lot less storage per spindle than you did with a disk, but drums were popular well into the 1960s for swapping and loading frequently used programs because they were so fast.
	www.memex.org /cm-archive9.html (18995 words)

	What is /dev/drum? [rec.humor.funny] (Site not responding. Last check: 2007-11-07)
		This seemed a bit odd, I thought > that drum memory went out of fashion long, long ago.
		A Bell Labs researcher who had just visited Africa seized upon the idea of communicating by beating on drums, as the native Africans did.
		He added a drum interface to his PDP-11 and the device driver was called, of course, /dev/drum.
	www.netfunny.com /rhf/jokes/91q1/devdrum.html (269 words)

	Mainframe
		The computer consisted of two tape units (each with two tape drives), a magnetic drum memory unit, a cathode-ray tube storage unit, an L-shaped arithmetic and control unit with an operator's panel, a card reader, a printer, a card punch and three power units.
		The memory is 6-bit (plus 1 parity bit) CORE memory, made out of little metal donuts strung on a wire mesh at IBM factories.
		With a memory reference speed of two microseconds (millionth of a second), the 7094 could in one second perform 500,000 logical decisions, 250,000 additions or subtractions, 100,000 multiplications or 62,500 divisions.
	www.thocp.net /hardware/mainframe.htm (3237 words)

	The IBM 650
		The IBM 650 Magnetic Drum Data Processing Machine was announced 2 July 1953 (as the "Magnetic Drum Calculator", or MDC), but not delivered until December 1954 (same time as the NORC).
		It was needed as a buffer between the drum and tapes, which transferred at different rates.
		The memory was a rotating magnetic drum with 2000 word (10 digits and sign) capacity and random access time of 2.496 ms.
	www.columbia.edu /acis/history/650.html (3432 words)

	IBM 650 (Site not responding. Last check: 2007-11-07)
		The 650 is a two-address, bi-quinary coded decimal machine (both data and addresses were decimal), with memory on a rotating drum.
		The rotating drum memory provided 2,000 10-digit words of memory, but was quite slow because a word could not be accessed until its location on the drum surface passed under the read/write heads during rotation (the average access time was 2.5ms).
		The optional Auxiliary Unit (Type 653), providing 60 10-digit words of magnetic core, was introduced on May 3, 1955 to provide a small fast memory (this device gave a memory access time of 96µs, a 26-fold raw improvement relative to the rotating drum).
	www.worldhistory.com /wiki/I/IBM-650.htm (353 words)

	Early Computers
		Not only was the main memory on magnetic drum, but so were the CPU registers, each on a dedicated track.
		The above is based on memory, supplemented by a brochure I have on the LGP-21, a transistorized version of the LGP-30 that General Precision tried to market.
		Disk memory was used to store the operating system, object code, and data, but not source code.
	world.std.com /~reinhold/dir/computer-history.html (3290 words)

	OS Project Description 2
		Drmint: invoked when the drum DMA unit generates an interrupt (a program transfer between the drum and memory has completed a swap).
		In order to swap a job into memory from the drum (say, job ComingIn), OS must invoke the memory manager to allocate a block of free memory for the job.
		When a job terminates, OS invokes the memory manager to deallocate the memory block that was allocated to the job.
	www.sci.brooklyn.cuny.edu /~jones/CIS25/osproj2.html (1968 words)

	THE
		There are "core pages" (in core memory) and "drum pages" (on the drum disk).
		The abstract memory unit presented to upper levels in the hierarchy is called the "segment" - many more segments than core pages exist, segments fit inside a core/drum page.
		Observation that it doesn't matter if programs' code pages are contiguous on drum, or even which drum page is used to back a core page.
	www-db.stanford.edu /~manku/quals/summaries/gribble-the.htm (439 words)

	Apollo Guidance Computer and Other Computer History
		A small prototype memory was built, and has achieved read cycle times of one microsecond, information access times of 0.3 microseconds, and a write time of 4 microseconds.
		For example, assigned memory addresses in the scratch-pad memory are used in place of the several arithmetic registers such as A, Q, and X, and counters, such as velocity and incremental accumulators required by conventional computers.
		Along with the reference to the drum memory in the introduction, above, the I/O section of the computer, along with being tailored for missle control, had an interface to a paper tape reader and punch.
	klabs.org /richcontent/Misc_Content/AGC_And_History/AGC_History.htm (10441 words)

	Computer Museum of America (Site not responding. Last check: 2007-11-07)
		The Digital Development Corporation Mass Storage Module Drive was used in the Control Data Corporation CDC-636 computer and represents an alternative memory technology that was crushed by the emergence of core memory technology.
		The drum rotates a 3,600 RPM, with a data transfer rate of 60 CPS.
		Once the unit reached its operational temperature, it had to cool down for three hours before the cover could be opened for servicing.
	www.computer-museum.org /main/collections/drmemdsk.shtml (109 words)

	[No title]
		If the number in memory location is of the same sign as the number in the accumulator, the result of subtraction is a number smaller in absolute value than the larger of the two numbers.
		As an example, suppose we N multiply 3 at q = 31 in the accumulator by 2 at q = 30 in memory.
		Divide the number in the accumulator by the number in memory location 2000 and place the quotient rounded to thirty bits in the accumulator The contents of memory location 2000 is unaffected.
	ed-thelen.org /comp-hist/lgp-30-man.html (15606 words)

	Welcome to Drum Corps World
		Crawford gained national and international prominence as musical director of three of America's greatest drum and bugle corps -- the Chicago Royal Airs, the Marine Corps' "Commandant's Own" and the Air Force's drum and bugle corps.
		Crawford revolutionized drum & bugle corps music by introducing his own spirited, jazz-based arrangements that literally broke (and buried forever!) the mold of the traditional "marching band-style" music that characterized drum corps in the 1950s.
		These veterans will, in turn, present the flags to the color guard of the Chicago Royal Airs, who will carry them proudly as a permanent memorial to their former musical director/arranger and beloved friend and mentor.
	www.drumcorpsworld.com /articles.cfm?ID=237 (277 words)

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