Difference between revisions of "Dover"

From Computer History Wiki
Jump to: navigation, search
m (→‎External links: Fix URL)
(Add details of the conversion from 7000 to Dover)
Line 1: Line 1:
−
'''Dovers''' were very early [[laser printer]]s, likely the first ones produced in any numbers. They were successors to an earlier laser printer prototype built at [[Xerox PARC]], the EARS; they were built out of cannibalized [[Xerox]] 7000 document photo-copiers.
+
'''Dovers''' were very early [[laser printer]]s, likely the first ones produced in any numbers, designed at [[Xerox PARC]]. They were more robust successors to an earlier laser printer prototype built at PARC, the EARS. They could produce output on ordinary paper at about one sheet per second.
  
−
Dovers were driven by a special [[device controller]] [[printed circuit board|card]], the Orbit, in a dedicated [[Xerox Alto]]. [[File]]s in [[Press]] format (a predecessor to [[PostScript]]) were printed by a [[spooler]], Spruce, which ran on the Alto. It communicated over the [[Ethernet]], using the [[PARC Universal Packet|PUP]] [[EFTP]] [[protocol]].
+
Dovers were driven by a special [[device controller]] [[printed circuit board|card]], the Orbit, in a dedicated [[Xerox Alto]]. A [[spooler]], Spruce, which ran on the Alto, oversaw the printing, which was done by a subsidiary program, Sprint. [[File]]s in [[Press]] format (a predecessor to [[PostScript]]) were sent to the spooler over the [[Ethernet]], using the [[PARC Universal Packet|PUP]] [[EFTP]] [[protocol]].  
  
−
Dover production started in 1976, when a small group of researchers at PARC, under John Ellenby, began buying used Xerox 7000 copiers, stripping out the existing document photo-copying optics, and replacing those with laser output heads; the copying optics were turned back in to the copier division, for credit. An early Dover was running in 1976, and many further ones were built, starting in 1977. PARC built three for their own use, and Electro Optical Systems in Pasadena made more (roughly 35 in total), for use elsewhere, in 1977-78.
+
Dover production started in 1976, when a small group of researchers at PARC, under John Ellenby, began buying used [[Xerox]] 7000 document photo-copiers and converting them to Dover printers. An early Dover was running in 1976, and many further ones were built, starting in 1977. PARC built three for their own use, and Electro Optical Systems in Pasadena made more (roughly 35 in total), for use elsewhere, in 1977-78.
  
−
Among the most important were several that were made part of the package of PARC equipment distributed to several prominent universities as part of a grant; [[Massachusetts Institute of Technology|MIT]], [[Stanford University|Stanford]] and [[CMU]] each received one.
+
Among the most important of those were several that were made part of the package of PARC equipment distributed to several prominent universities as part of a grant; [[Massachusetts Institute of Technology|MIT]], [[Stanford University|Stanford]] and [[CMU]] each received one.
 +
 
 +
==Conversion==
 +
 
 +
Dovers were built out of cannibalized Xerox 7000 copiers; the existing document photo-copying optics were stripped out, and replaced with laser output units, the Raster Output Scanner (ROS). (The Electronic Image Processor (EIP) for the Dover is the interface between the Alto and the ROS.) The entire paper-handling path mechanical hardware of the 7000 was retained, un-changed. After conversion, the copying optics were turned back in to the copier division, for credit.
 +
 
 +
Components removed included:
 +
 
 +
* optical system
 +
* control logic
 +
* contact relay
 +
* control console
 +
* top cover
 +
* top harness
 +
 
 +
Components retained, un-disturbed, included:
 +
 
 +
* paper feeder
 +
* paper transports
 +
* engines
 +
* solenoid
 +
* paper path sensing switches
 +
 
 +
Components added included:
 +
 
 +
* laser system
 +
* engine control module
 +
* solid state relay
 +
* control console
 +
* top cover
 +
* top harness
 +
* adapter modules
 +
 
 +
The added electronics are primarily contained on 5 cards plugged into a [[backplane]]:
 +
 
 +
* Command Adapter
 +
* Video Adapter
 +
* Motor Driver
 +
* Engine Control
 +
* Relay Board
 +
 
 +
All aspects of the operation of the new printing system were controlled by software in the Alto.
  
 
==External links==
 
==External links==
Line 13: Line 54:
 
* [https://www.computerhistory.org/collections/catalog/X750.86 Dover Laser Printer]
 
* [https://www.computerhistory.org/collections/catalog/X750.86 Dover Laser Printer]
 
* [https://www.computerhistory.org/collections/catalog/102803906 Xerox Dover in MIT AI Lab] - the caption is erroneous; the Dover was actually shared between the [[MIT Artificial Intelligence Laboratory|AI Lab]] and [[MIT Laboratory for Computer Science|LCS]]; note also the Alto which drove it, under the table
 
* [https://www.computerhistory.org/collections/catalog/102803906 Xerox Dover in MIT AI Lab] - the caption is erroneous; the Dover was actually shared between the [[MIT Artificial Intelligence Laboratory|AI Lab]] and [[MIT Laboratory for Computer Science|LCS]]; note also the Alto which drove it, under the table
−
 
−
{{semi-stub}}
 
  
 
[[Category: Printers]]
 
[[Category: Printers]]

Revision as of 02:01, 17 November 2024

Dovers were very early laser printers, likely the first ones produced in any numbers, designed at Xerox PARC. They were more robust successors to an earlier laser printer prototype built at PARC, the EARS. They could produce output on ordinary paper at about one sheet per second.

Dovers were driven by a special device controller card, the Orbit, in a dedicated Xerox Alto. A spooler, Spruce, which ran on the Alto, oversaw the printing, which was done by a subsidiary program, Sprint. Files in Press format (a predecessor to PostScript) were sent to the spooler over the Ethernet, using the PUP EFTP protocol.

Dover production started in 1976, when a small group of researchers at PARC, under John Ellenby, began buying used Xerox 7000 document photo-copiers and converting them to Dover printers. An early Dover was running in 1976, and many further ones were built, starting in 1977. PARC built three for their own use, and Electro Optical Systems in Pasadena made more (roughly 35 in total), for use elsewhere, in 1977-78.

Among the most important of those were several that were made part of the package of PARC equipment distributed to several prominent universities as part of a grant; MIT, Stanford and CMU each received one.

Conversion

Dovers were built out of cannibalized Xerox 7000 copiers; the existing document photo-copying optics were stripped out, and replaced with laser output units, the Raster Output Scanner (ROS). (The Electronic Image Processor (EIP) for the Dover is the interface between the Alto and the ROS.) The entire paper-handling path mechanical hardware of the 7000 was retained, un-changed. After conversion, the copying optics were turned back in to the copier division, for credit.

Components removed included:

  • optical system
  • control logic
  • contact relay
  • control console
  • top cover
  • top harness

Components retained, un-disturbed, included:

  • paper feeder
  • paper transports
  • engines
  • solenoid
  • paper path sensing switches

Components added included:

  • laser system
  • engine control module
  • solid state relay
  • control console
  • top cover
  • top harness
  • adapter modules

The added electronics are primarily contained on 5 cards plugged into a backplane:

  • Command Adapter
  • Video Adapter
  • Motor Driver
  • Engine Control
  • Relay Board

All aspects of the operation of the new printing system were controlled by software in the Alto.

External links

Retrieved from "https://gunkies.org/w/index.php?title=Dover&oldid=35514"