Williams tube - Revision history

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Machines that used Williams tube

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New page

The '''Williams tube''' was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used electrostatic storage (i.e. groups of [[electron]]s) on the face of a [[cathode ray tube]].

Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.

The basic physical process used was 'secondary emission'; when the electron beam of the CRT hit the phosphor on the tube face, emits extra electrons, leaving a spot which is depleted of electrons. This leaves a 'well', a spot of electric charge. If the beam is then directed to a nearby spot, secondary electrons from that will fill the well.

This effect can be used to store data; if the well is left intact, that spot can be taken to represent 0, and if the well is filled, than can be 1.

To read the data out, the beam is briefly directed toward the original spot; depending on whether it held a well, or nothing, a tiny electrical signal is produced which can be picked up on a [[conductor]] plate placed close to the tube face, and [[amplifier|amplified]].

The charge wells tended to disappear fairly quickly, so the data had to be [[refresh]]ed at a fairly high rate.

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 * [https://curation.cs.manchester.ac.uk/computer50/www.computer50.org/kgill/mark1/report1947cover.html Covering Notes for Tom Kilburn's 1947 report to TRE: ''A Storage System for Use with Binary Digital Computing Machines'']
 * [https://www.computerhistory.org/revolution/memory-storage/8/308 Williams-Kilburn Tubes]
 [[Category: Memory Basics]]

@@ Line 1: / Line 1: @@
 The '''Williams tube''' (also called the '''Williams-Kilburn tube'''), invented by Frederic C. Williams and Tom Kilburn, was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]] (CRT). Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.
-Among the early computers to use it were the [[Manchester Baby]] (and its descendants, the [[Manchester Mark I]] and [[Ferranti Mark I]]), the [[IAS computer]] (and most of its many clones, too many to list here), the [[IBM 701]] and [[IBM 702|702]], and the [[ERA 1103]].
+Among the early computers to use it were the [[Manchester Baby]] (and its descendants, the [[Manchester Mark I]] and [[Ferranti Mark 1]]), the [[IAS computer]] (and most of its many clones, too many to list here), the [[IBM 701]] and [[IBM 702|702]], and the [[ERA 1103]].
 ==Details==

@@ Line 1: / Line 1: @@
-The '''Williams tube''', invented by Frederic C. Williams and Tom Kilburn, was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]] (CRT). Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.
+The '''Williams tube''' (also called the '''Williams-Kilburn tube'''), invented by Frederic C. Williams and Tom Kilburn, was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]] (CRT). Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.
 Among the early computers to use it were the [[Manchester Baby]] (and its descendants, the [[Manchester Mark I]] and [[Ferranti Mark I]]), the [[IAS computer]] (and most of its many clones, too many to list here), the [[IBM 701]] and [[IBM 702|702]], and the [[ERA 1103]].
@@ Line 16: / Line 16: @@
 * [https://curation.cs.manchester.ac.uk/computer50/www.computer50.org/kgill/mark1/report1947cover.html Covering Notes for Tom Kilburn's 1947 report to TRE: ''A Storage System for Use with Binary Digital Computing Machines'']
 [[Category: Memory Basics]]

@@ Line 1: / Line 1: @@
-The '''Williams tube''' was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]] (CRT).
+The '''Williams tube''', invented by Frederic C. Williams and Tom Kilburn, was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]] (CRT). Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.
-Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.
+Among the early computers to use it were the [[Manchester Baby]] (and its descendants, the [[Manchester Mark I]] and [[Ferranti Mark I]]), the [[IAS computer]] (and most of its many clones, too many to list here), the [[IBM 701]] and [[IBM 702|702]], and the [[ERA 1103]].
 The basic physical process used was 'secondary emission'; when the [[electron]] beam of the CRT hits the phosphor on the tube face, it emits extra electrons, leaving a spot which is depleted of electrons. This leaves a 'well', a spot of electric charge. If the beam is then directed to a nearby spot, secondary electrons from that will fill the well.
@@ Line 10: / Line 12: @@
 The charge wells tended to disappear fairly quickly, so the data had to be [[memory refresh|refreshed]] at a fairly high rate.
 [[Category: Memory Basics]]

@@ Line 1: / Line 1: @@
-The '''Williams tube''' was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]].
+The '''Williams tube''' was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]] (CRT).
 Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.
-The basic physical process used was 'secondary emission'; when the electron beam of the CRT hit the phosphor on the tube face, emits extra electrons, leaving a spot which is depleted of electrons. This leaves a 'well', a spot of electric charge. If the beam is then directed to a nearby spot, secondary electrons from that will fill the well.
+The basic physical process used was 'secondary emission'; when the [[electron]] beam of the CRT hits the phosphor on the tube face, it emits extra electrons, leaving a spot which is depleted of electrons. This leaves a 'well', a spot of electric charge. If the beam is then directed to a nearby spot, secondary electrons from that will fill the well.
-This effect can be used to store data; if the well is left intact, that spot can be taken to represent 0, and if the well is filled, than can be 1.
+This effect can be used to store data; if the well is left intact, that spot can be taken to represent 0, and if the well is filled, that can be 1.
 To read the data out, the beam is briefly directed toward the original spot; depending on whether it held a well, or nothing, a tiny electrical signal is produced which can be picked up on a [[conductor]] plate placed close to the tube face, and [[amplifier|amplified]].
-The charge wells tended to disappear fairly quickly, so the data had to be [[refresh]]ed at a fairly high rate.
+The charge wells tended to disappear fairly quickly, so the data had to be [[memory refresh|refreshed]] at a fairly high rate.
 [[Category: Memory Basics]]

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		+	[[Category: Memory Basics]]

← Older revision		Revision as of 21:20, 7 October 2018
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−	The '''Williams tube''' was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used ~~electrostatic storage (i.e. groups of~~ [[~~electron~~]]s) on the face of a [[cathode ray tube]].	+	The '''Williams tube''' was one of the technologies used for [[main memory]] in the very earliest computers, along with [[delay line]]s and [[drum]]s. It used [[electrostatic]] storage on the face of a [[cathode ray tube]].

	Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.		Although it needed very subtle [[electronics]], the advantage over the other two was that it was [[random access]]; the time to gain access to any particular bit was constant.