Delay line - Revision history

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‎External links: trim URL

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+Computers that used them

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‎Delay line memory: Need optimum programming when used for main memory

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modern implementation

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+cat

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Mention non-acoustic

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A decent start

New page

A '''delay line''' is a device which takes in a [[signal]], and sends it out again after a delay. They were the base technology for a common choice for early [[main memory]].

The ones used in early computers were '''acoustic delay lines''', which consisted of a transducer (speaker) which sent sound signals into a channel filled with a suitable material (mercury was often used), with another transducer (acting as a microphone) at the other end.

A string of [[bit]]s could be stored in the delay line by taking its output, sending it through some [[electronic]]s (including an [[amplifier]]) to 'clean up' the signal, and then directing it back to the start of the delay line for re-insertion.

Although they were cheap and simple, they had one large drawback; they were not [[random access]]. If the computer needed a value that had just been sent into the delay line, it had to wait until it emerged at the other end. This made alternatives such as [[Williams tube]] storage attractive, despite their issues.

Once [[core memory]] appeared, delay line memories rapidly disappeared.

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 ==External links==
-* [https://onlineonly.christies.com/s/firsts-history-computing-paul-g-allen-collection/univac-mercury-delay-line-memory-104/230041?ldp_breadcrumb=back UNIVAC mercury delay line memory] - includes images
+* [https://onlineonly.christies.com/s/firsts-history-computing-paul-g-allen-collection/univac-mercury-delay-line-memory-104/230041 UNIVAC mercury delay line memory] - includes images
 [[Category: Memory Basics]]

← Older revision		Revision as of 12:30, 21 April 2025
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	{{semi-stub}}		{{semi-stub}}
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		+	==External links==
		+
		+	* [https://onlineonly.christies.com/s/firsts-history-computing-paul-g-allen-collection/univac-mercury-delay-line-memory-104/230041?ldp_breadcrumb=back UNIVAC mercury delay line memory] - includes images

	[[Category: Memory Basics]]		[[Category: Memory Basics]]

← Older revision		Revision as of 18:29, 18 March 2024
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	Although they were cheap and simple, they had one large drawback; they were not [[random access]]. If the computer needed a value that had just been sent into the delay line, it had to wait until it emerged at the other end. This often required the use of [[optimum programming]], to control the execution delays which resulted if [[instruction]]s were not placed in the optimum positions in the delay line. This made alternatives such as [[Williams tube]] storage attractive, despite their issues.		Although they were cheap and simple, they had one large drawback; they were not [[random access]]. If the computer needed a value that had just been sent into the delay line, it had to wait until it emerged at the other end. This often required the use of [[optimum programming]], to control the execution delays which resulted if [[instruction]]s were not placed in the optimum positions in the delay line. This made alternatives such as [[Williams tube]] storage attractive, despite their issues.
		+
		+	Still, despite delay lines' inherent problems, several important and influential families of early computers used them:
		+
		+	* [[Automatic Computing Engine\|ACE]] ([[Pilot ACE]], [[DEUCE]])
		+	* [[EDSAC]] ([[LEO]])
		+	* [[EDVAC]] ([[UNIVAC I]])

	Once [[core memory]] appeared, delay line memories rapidly disappeared.		Once [[core memory]] appeared, delay line memories rapidly disappeared.

← Older revision		Revision as of 12:12, 23 September 2019
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−	A '''delay line''' is a device which takes in a [[signal]], and sends it out again after a delay. They were the base technology for a common choice for early [[main memory]].	+	A '''delay line''' is a device which takes in a [[signal]], and sends it out again after a short delay. They were the base technology for a common choice for early [[main memory]].
		+
		+	They are now usually implemented with [[capacitor]]-[[inductor]] neworks; they appeared in [[Dual Inline Package\|DIP]] format shortly after that was introduced.
		+
		+	==Delay line memory==

	The ones used in early computers were '''acoustic delay lines''', which consisted of a transducer (speaker) which sent sound signals into a channel filled with a suitable material (mercury was often used), with another transducer (acting as a microphone) at the other end. (There are other ways to produce delay lines, but the ones used in computer memories generally used the acoustic approach.)		The ones used in early computers were '''acoustic delay lines''', which consisted of a transducer (speaker) which sent sound signals into a channel filled with a suitable material (mercury was often used), with another transducer (acting as a microphone) at the other end. (There are other ways to produce delay lines, but the ones used in computer memories generally used the acoustic approach.)

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		+	[[Category: Memory Basics]]

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 A string of [[bit]]s could be stored in the delay line by taking its output, sending it through some [[electronic]]s (including an [[amplifier]]) to 'clean up' the signal, and then directing it back to the start of the delay line for re-insertion.
-Although they were cheap and simple, they had one large drawback; they were not [[random access]]. If the computer needed a value that had just been sent into the delay line, it had to wait until it emerged at the other end. This made alternatives such as [[Williams tube]] storage attractive, despite their issues.
+Although they were cheap and simple, they had one large drawback; they were not [[random access]]. If the computer needed a value that had just been sent into the delay line, it had to wait until it emerged at the other end. This often required the use of [[optimum programming]], to control the execution delays which resulted if [[instruction]]s were not placed in the optimum positions in the delay line. This made alternatives such as [[Williams tube]] storage attractive, despite their issues.
 Once [[core memory]] appeared, delay line memories rapidly disappeared.

@@ Line 1: / Line 1: @@
 A '''delay line''' is a device which takes in a [[signal]], and sends it out again after a delay. They were the base technology for a common choice for early [[main memory]].
-The ones used in early computers were '''acoustic delay lines''', which consisted of a transducer (speaker) which sent sound signals into a channel filled with a suitable material (mercury was often used), with another transducer (acting as a microphone) at the other end.
+The ones used in early computers were '''acoustic delay lines''', which consisted of a transducer (speaker) which sent sound signals into a channel filled with a suitable material (mercury was often used), with another transducer (acting as a microphone) at the other end. (There are other ways to produce delay lines, but the ones used in computer memories generally used the acoustic approach.)
 A string of [[bit]]s could be stored in the delay line by taking its output, sending it through some [[electronic]]s (including an [[amplifier]]) to 'clean up' the signal, and then directing it back to the start of the delay line for re-insertion.