IMLAC PDS-1 - Revision history

Jnc: /* External links */ Good caption for link; add front panel image

2025-06-27T21:51:47Z

‎External links: Good caption for link; add front panel image

Larsbrinkhoff: /* Differences between Alpha and Graphics machines */ Link to Freeway Crossing article.

2025-06-26T10:04:45Z

‎Differences between Alpha and Graphics machines: Link to Freeway Crossing article.

Larsbrinkhoff: Programmable Display System. We ought to mention PDS-4 somewhere, but maybe not on a separate page.

2025-06-10T05:54:42Z

Programmable Display System. We ought to mention PDS-4 somewhere, but maybe not on a separate page.

Jnc: /* External links */ Another copy of 'IMLAC PDS-1D Programming Guide'

2025-06-09T15:00:06Z

‎External links: Another copy of 'IMLAC PDS-1D Programming Guide'

Jnc: Jnc moved page Imlac PDS-1 to IMLAC PDS-1: Case as per original docs

2025-06-09T14:42:08Z

Jnc moved page Imlac PDS-1 to IMLAC PDS-1: Case as per original docs

Jnc: Expand description to a basic thumbnail; add ext links to manuals, etc

2025-06-09T14:40:20Z

Expand description to a basic thumbnail; add ext links to manuals, etc

Larsbrinkhoff: Claim to fame.

2025-06-09T12:42:01Z

Claim to fame.

Larsbrinkhoff: Differences between Alpha and Graphics machines

2025-06-09T07:30:44Z

Differences between Alpha and Graphics machines

Jnc: +Ext link

2023-03-29T13:35:57Z

+Ext link

Jnc: +External links, link

2019-02-21T15:08:37Z

+External links, link

@@ Line 26: / Line 26: @@
 ** [http://www.bitsavers.org/pdf/imlac/PDS-1_TechnicalMan.pdf IMLAC PDS-1 Programmable Display System Preliminary Technical and Operator Manual]
 ** [http://www.bitsavers.org/pdf/imlac/PDS-1D_ProgrammingGuide.pdf IMLAC PDS-1D Programming Guide] <!-- also http://www.ubanproductions.com/ImlacDocs/PDS-1D_ProgrammingGuide.pdf -->
-* [http://www.ubanproductions.com/imlac.html Imlac Anatomy]
+* [http://www.ubanproductions.com/imlac.html Imlac Anatomy] - large collection of very good images of a PDS-1D; details of getting Maze War running at the 2004 7th annual West Coast Vintage Computer Festival
 ** [http://www.ubanproductions.com/imlac_sw.html Imlac Software Library] - includes many IMLAC documents, not all of which are at Bitsavers (above)
 * [http://www.blinkenlights.com/classiccmp/imlac/ Imlac PDS-1]
 * [https://github.com/larsbrinkhoff/imlac-software/blob/master/washington/Screen%20Addressing%20in%20FREEWAY%20(1971)%20for%20the%20IMLAC%20PDS-1.pdf Screen Addressing in FREEWAY (1970) for the IMLAC PDS-1]
 [[Category: Workstations]]

@@ Line 9: / Line 9: @@
 ==Differences between Alpha and Graphics machines==
-The first type of the IMLAC PDS-1 was called an ''Alpha machine'', and had a somewhat less capable display processor than the later ''Graphics machines''.  There is no surviving documentation for the Alpha machine, but the details have been reverse engineered by Zachary Harper from the listing for the '''Freeway Crossing''' game.
+The first type of the IMLAC PDS-1 was called an ''Alpha machine'', and had a somewhat less capable display processor than the later ''Graphics machines''.  There is no surviving documentation for the Alpha machine, but the details have been reverse engineered by Zachary Harper from the listing for the '''[[Freeway Crossing]]''' game.
 On an Alpha machine, the D LDXA and D LDYA instructions load bits 4 to 10 into the accumulator MSB.  On a Graphics machine, bits 6-11 load into the MSB.  On both machines, bits 12-16 are loaded into the LSB, and the least significant "½ point" bit is cleared.

@@ Line 1: / Line 1: @@
-The '''IMLAC PDS-1''' was a very early [[workstation]] (1970, well before the [[Xerox Alto]]). It generally did not have any [[secondary storage]], and was mostly used only as a [[terminal]] on a larger system, communicating with it via an [[asynchronous serial line]].
+The '''IMLAC PDS-1''' was a very early [[workstation]] (1970, well before the [[Xerox Alto]]).  PDS means Programmable Display System.  It generally did not have any [[secondary storage]], and was mostly used only as a [[terminal]] on a larger system, communicating with it via an [[asynchronous serial line]].
 This computer was host to the first version of the game [[Maze War]].  As a terminal, it was used to develop the game [[Zork]], and edit the manuscript for the book ''Gödel, Escher, Bach''.
@@ Line 5: / Line 5: @@
 It had a [[vector graphics]] [[display]], controlled by a [[display program]] in the machine's [[main memory]] ([[core memory]], at that point in time). It also included a small 16-bit [[minicomputer]]; the two shared access to the main memory, with the display processor having priority for access. The [[Central Processing Unit|CPU]] (said by many to be reminiscent of a [[PDP-8 family|PDP-8]]) was built out of [[74 series]] [[integrated circuit|ICs]], and had a classical [[front panel]] for control. The display was a [[cathode ray tube|CRT]].
-There were several different variants; the original 'PDS-1' had an [[instruction]] [[cycle time]] of 2.0 μsec, and the 'PDS-1D' had a cycle time of 1.8 μsec, but seems otherwise to have been almost identical. There were also 'Alpha' and 'Graphics' versions (see below); the PDS-1D was a 'Graphics' machine.
+There were several different variants; the original 'PDS-1' had an [[instruction]] [[cycle time]] of 2.0 μsec, and the 'PDS-1D' had a cycle time of 1.8 μsec, but seems otherwise to have been almost identical. There were also 'Alpha' and 'Graphics' versions (see below); the PDS-1D was a 'Graphics' machine.  The last model was called PDS-4, with a memory cycle of "less than a microsecond" and optional floating point hardware.
 ==Differences between Alpha and Graphics machines==

@@ Line 25: / Line 25: @@
 * [http://www.bitsavers.org/pdf/imlac/ imlac] - documentation at [[Bitsavers]]
 ** [http://www.bitsavers.org/pdf/imlac/PDS-1_TechnicalMan.pdf IMLAC PDS-1 Programmable Display System Preliminary Technical and Operator Manual]
-** [http://www.bitsavers.org/pdf/imlac/PDS-1D_ProgrammingGuide.pdf IMLAC PDS-1D Programming Guide]
+** [http://www.bitsavers.org/pdf/imlac/PDS-1D_ProgrammingGuide.pdf IMLAC PDS-1D Programming Guide] <!-- also http://www.ubanproductions.com/ImlacDocs/PDS-1D_ProgrammingGuide.pdf -->
 * [http://www.ubanproductions.com/imlac.html Imlac Anatomy]
 ** [http://www.ubanproductions.com/imlac_sw.html Imlac Software Library] - includes many IMLAC documents, not all of which are at Bitsavers (above)

@@ Line 1: / Line 1: @@
-An '''Imlac PDS-1''' was a very early [[workstation]] (1970, well before the [[Xerox Alto]]), with a [[vector graphics]] [[display]]. It generally did not have any [[secondary storage]], and was only a [[terminal]] on a larger system.
+The '''IMLAC PDS-1''' was a very early [[workstation]] (1970, well before the [[Xerox Alto]]). It generally did not have any [[secondary storage]], and was mostly used only as a [[terminal]] on a larger system, communicating with it via an [[asynchronous serial line]].
 This computer was host to the first version of the game [[Maze War]].  As a terminal, it was used to develop the game [[Zork]], and edit the manuscript for the book ''Gödel, Escher, Bach''.
-{{stub}}
+It had a [[vector graphics]] [[display]], controlled by a [[display program]] in the machine's [[main memory]] ([[core memory]], at that point in time). It also included a small 16-bit [[minicomputer]]; the two shared access to the main memory, with the display processor having priority for access. The [[Central Processing Unit|CPU]] (said by many to be reminiscent of a [[PDP-8 family|PDP-8]]) was built out of [[74 series]] [[integrated circuit|ICs]], and had a classical [[front panel]] for control. The display was a [[cathode ray tube|CRT]].
 ==Differences between Alpha and Graphics machines==
-The first type of the Imlac PDS-1 was called an ''Alpha machine'', and had a somewhat less capable display processor than the later ''Graphics machines''.  There is no surviving documentation for the Alpha machine, but the details have been reverse engineered by Zachary Harper from the listing for the '''Freeway Crossing''' game.
+The first type of the IMLAC PDS-1 was called an ''Alpha machine'', and had a somewhat less capable display processor than the later ''Graphics machines''.  There is no surviving documentation for the Alpha machine, but the details have been reverse engineered by Zachary Harper from the listing for the '''Freeway Crossing''' game.
 On an Alpha machine, the D LDXA and D LDYA instructions load bits 4 to 10 into the accumulator MSB.  On a Graphics machine, bits 6-11 load into the MSB.  On both machines, bits 12-16 are loaded into the LSB, and the least significant "½ point" bit is cleared.
@@ Line 16: / Line 18: @@
 On an Alpha machine, incrementing or decrementing the MSB is done according to the scale factor.  On a Graphics machine, it's done by 1.
 ==External links==
 * [http://www.ubanproductions.com/imlac.html Imlac Anatomy]
 * [http://www.blinkenlights.com/classiccmp/imlac/ Imlac PDS-1]
 * [https://github.com/larsbrinkhoff/imlac-software/blob/master/washington/Screen%20Addressing%20in%20FREEWAY%20(1971)%20for%20the%20IMLAC%20PDS-1.pdf Screen Addressing in FREEWAY (1970) for the IMLAC PDS-1]
 [[Category: Workstations]]

← Older revision	Revision as of 14:42, 9 June 2025
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← Older revision		Revision as of 12:42, 9 June 2025
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	An '''Imlac PDS-1''' was a very early [[workstation]] (1970, well before the [[Xerox Alto]]), with a [[vector graphics]] [[display]]. It generally did not have any [[secondary storage]], and was only a [[terminal]] on a larger system.		An '''Imlac PDS-1''' was a very early [[workstation]] (1970, well before the [[Xerox Alto]]), with a [[vector graphics]] [[display]]. It generally did not have any [[secondary storage]], and was only a [[terminal]] on a larger system.
		+
		+	This computer was host to the first version of the game [[Maze War]]. As a terminal, it was used to develop the game [[Zork]], and edit the manuscript for the book ''Gödel, Escher, Bach''.

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