Drum - Revision history

Jnc: /* External links */ +Storage of Numbers on Magnetic Tape

2025-06-02T14:07:43Z

‎External links: +Storage of Numbers on Magnetic Tape

Jnc: Problem with very large drums

2025-06-02T13:15:18Z

Problem with very large drums

Jnc: Tweak order, add LGP-30

2024-03-18T18:45:20Z

Tweak order, add LGP-30

Jnc: Need optimum programming if used for main memory

2024-03-17T15:53:21Z

Need optimum programming if used for main memory

Jnc: minor tweaks

2020-09-01T21:18:25Z

minor tweaks

Jnc: typo

2018-12-13T14:39:20Z

typo

Jnc: +cat

2018-12-13T14:38:34Z

+cat

Jnc: Yes, that was why

2018-04-14T19:06:55Z

Yes, that was why

Jnc: +link

2017-09-30T12:57:22Z

+link

Jnc: Add a bit more detail

2017-09-24T14:40:41Z

Add a bit more detail

@@ Line 13: / Line 13: @@
 ==External links==
 * [https://www.fourmilab.ch/documents/univac/fastrand.html The FASTRAND™ II] - amusing detailed description of the very large drum used on the [[UNIVAC 1100]] series
 [[Category: Device Basics]]

← Older revision		Revision as of 13:15, 2 June 2025
Line 8:		Line 8:

	Drums fell out of use in large part because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, giving in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.		Drums fell out of use in large part because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, giving in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.
		+
		+	The very large (physically) FASTRAND I drum from [[Remington Rand Univac‎]] displayed another, previously unthought-of, issue. It had only a single, massive, drum; a massive drum rotating at high speed acts as a powerful gyroscope, which tries to stay in a fixed attitude with respect to an inertial frame of reference. As the Earth rotated, this led to the FASTRAND I tending to move around the computer room! The successor, the FASTRAND II, therefore had ''two'' physical drums, rotating in opposite directions!
		+
		+	==External links==
		+
		+	* [https://www.fourmilab.ch/documents/univac/fastrand.html The FASTRAND™ II] - amusing detailed description of the very large drum used on the [[UNIVAC 1100]] series

	[[Category: Device Basics]]		[[Category: Device Basics]]

@@ Line 1: / Line 1: @@
-'''Drums''' were the predecessor [[magnetic storage]] technology to [[disk]]s; they were (as the name suggests) in physical form a drum, and generally had a [[head]] per [[track]] (like [[fixed-head disk]]s).
+'''Drums''' were the predecessor [[magnetic storage]] technology to [[disk]]s; they were (as the name suggests) in physical form a drum.
-Like fixed-head disks, this avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components; drums also needed more volume for their installation.
+They generally had a [[head]] per [[track]], like [[fixed-head disk]]s. Like them, on drums this avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components. Because of their fundamental geometry, drums also needed more volume for their installation than disks did.
-The very first drums were actually used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones (e.g. the [[IBM 650]] and [[Bendix G-15]]). Such use often required the use of [[optimum programming]], to control the execution delays (due to rotational latency) which resulted if [[instruction]]s were not placed in the optimum positions on the drum. Some drums were actually used to store [[register]]s, storing several registers in each track, and using multiple heads on that track to give faster access to the contents of the registers.
+The very first drums were actually used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones (notably the [[IBM 650]], [[Bendix G-15]], and [[LGP-30]]). Such use often required the use of [[optimum programming]], to control the execution delays (due to rotational latency) which resulted if [[instruction]]s were not placed in the optimum positions on the drum. Some drums were actually used to store [[register]]s, storing several registers in each track, and using multiple heads on that track to give faster access to the contents of the registers.
 Once [[core memory]] appeared, drums were only seen in the role of high-speed [[secondary storage]]; often being used for [[swapping]] or [[virtual memory|paging]] purposes.
-Drums fell out of use because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, giving in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.
+Drums fell out of use in large part because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, giving in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.
 [[Category: Device Basics]]

@@ Line 3: / Line 3: @@
 Like fixed-head disks, this avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components; drums also needed more volume for their installation.
-The very first drums were actuallly used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones (e.g. the [[IBM 650]]). Some drums were actually used to store [[register]]s, storing several registers in each track, and using multiple heads on that track to give faster access to the contents of the registers.
+The very first drums were actually used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones (e.g. the [[IBM 650]] and [[Bendix G-15]]). Such use often required the use of [[optimum programming]], to control the execution delays (due to rotational latency) which resulted if [[instruction]]s were not placed in the optimum positions on the drum. Some drums were actually used to store [[register]]s, storing several registers in each track, and using multiple heads on that track to give faster access to the contents of the registers.
 Once [[core memory]] appeared, drums were only seen in the role of high-speed [[secondary storage]]; often being used for [[swapping]] or [[virtual memory|paging]] purposes.

@@ Line 1: / Line 1: @@
 '''Drums''' were the predecessor [[magnetic storage]] technology to [[disk]]s; they were (as the name suggests) in physical form a drum, and generally had a [[head]] per [[track]] (like [[fixed-head disk]]s).
-This avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components.
+Like fixed-head disks, this avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components; drums also needed more volume for their installation.
 The very first drums were actuallly used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones (e.g. the [[IBM 650]]). Some drums were actually used to store [[register]]s, storing several registers in each track, and using multiple heads on that track to give faster access to the contents of the registers.
@@ Line 7: / Line 7: @@
 Once [[core memory]] appeared, drums were only seen in the role of high-speed [[secondary storage]]; often being used for [[swapping]] or [[virtual memory|paging]] purposes.
-Drums fell out of use because they took more physical space than a disk with the equivalent surface area. A number of [[disk platter]]s, given in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.
+Drums fell out of use because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, giving in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.
 [[Category: Device Basics]]

← Older revision		Revision as of 19:06, 14 April 2018
Line 7:		Line 7:
	Once [[core memory]] appeared, drums were only seen in the role of high-speed [[secondary storage]]; often being used for [[swapping]] or [[paging]] purposes.		Once [[core memory]] appeared, drums were only seen in the role of high-speed [[secondary storage]]; often being used for [[swapping]] or [[paging]] purposes.

−	Drums ~~likely~~ fell out of use because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, given in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.	+	Drums fell out of use because they took more physical room than a disk with the equivalent surface area. A number of [[disk platter]]s, given in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.

← Older revision		Revision as of 12:57, 30 September 2017
Line 1:		Line 1:
−	'''Drums''' were the predecessor magnetic storage technology to [[disk]]s; they were (as the name suggests) in physical form a drum, and generally had a [[head]] per [[track]] (like [[fixed-head disk]]s).	+	'''Drums''' were the predecessor [[magnetic storage]] technology to [[disk]]s; they were (as the name suggests) in physical form a drum, and generally had a [[head]] per [[track]] (like [[fixed-head disk]]s).

	This avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components.		This avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components.

@@ Line 1: / Line 1: @@
-'''Drums''' were the predecessor magnetic storage technology to [[disk]]s; they were (as the name suggests) in physical form a drum, and generally had a head per track (like [[fixed-head disk]]s.
+'''Drums''' were the predecessor magnetic storage technology to [[disk]]s; they were (as the name suggests) in physical form a drum, and generally had a [[head]] per [[track]] (like [[fixed-head disk]]s).
-The very first drums were actuallly used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones. Once [[core memory]] appeared, drums were only seen in the role of high-speed [[secondary storage]]; often being used for [[swapping]] or [[paging]] purposes.
+This avoided the delays involved in having the head(s) [[seek]] to the correct track, and was also mechanically simpler (an important point at this early stage of development), but did require more components.
-Drums likely fell out of use because they took more physical space than a disk with the equivalent surface area. A number of [[disk platter]]s, given in total a significantly greater amount of storage, could be stacked in the volume occupied by a single drum.
+The very first drums were actuallly used for [[main memory]] on some very early computers; and also on slightly later, but low-end, ones. Some drums were actually used to store [[register]]s, storing several registers in each track, and using multiple heads on that track to give faster access to the contents of the registers.