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{{Infobox computer hardware |
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{{csb-pageincludes|1=http://en.wikichip.org/Gemini_Guidance_Computer}} |
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| name = Gemini Guidance Computer |
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| image = Gemini_Guidance_Computer_(NASM).JPG |
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| caption = Gemini Guidance Computer in ] |
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| invent-name = ] |
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| manufacturer = ] |
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| introduced = {{Start date and age|1965}} |
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| discontinued = {{Start date and age|1966}} |
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| type = Avionics<br>Guidance Computer |
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| processor = Discrete Components <ref>{{Cite web|url=https://history.nasa.gov/computers/Ch1-2.html|title=Ch1-2|date=March 1988 |last1=Tomayko |first1=James E. }}</ref> |
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| frequency = 7.143 kilohertz clock |
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| memory = 39-bit words memory, each composed of three ]s, 4,096 words of memory, in a ferrite core array. |
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| ports = Modular Display Keyboard (MDK), Modular Display Readout (MDR), Attitude Control and Maneuver Electronics (ACME), Inertial Measurement Unit (IMU), Horizon Sensors, Time Reference System (TRS)<ref>{{Cite web|url=http://www.ibiblio.org/apollo/Gemini.html#Peripheral_Devices|title=The Gemini Spacecraft Computer}}</ref> |
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| weight = {{cvt|58.98|lbs|kg}} |
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| dimensions = {{cvt|18.9|×|14.5|×|12.75|in|cm}} (H)×(W)×(D) |
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}} |
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The '''Gemini Guidance Computer''' (sometimes '''Gemini Spacecraft On-Board Computer''' ('''OBC''')) was a ], ] designed for ], America's second human spaceflight project.<ref name="manual" /> The computer, which facilitated the control of mission maneuvers, was designed by the ].<ref name="ibm">8. J. C. Hundley and R. A. Watson, "A Digital Computer in Orbital Flight," TR 63-825-892, IBM Federal Systems Division, Owego, New York, October 1964.</ref> |
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The '''Gemini Guidance Computer''' (sometimes '''Gemini Spacecraft On-Board Computer''' (OBC)) was a ], ] designed for ], America's second man-in-space effort.<ref name="manual" /> The computer, which facilitated the control of mission maneuvers, was designed by the ].<ref name="ibm">8. J. C. Hundley and R. A. Watson, "A Digital Computer in Orbital Flight," TR 63-825-892, IBM Federal Systems Division, Owego, New York, October 1964.</ref> |
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== History == |
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] |
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Project Mercury was America's first man-in-space effort. Due to its simplicity and size, however, it did not have any independent maneuvering capability. The re-entry retrofire times and firing attitude were calculated by computing center on the ground and were transmitted in real-time to the spacecraft. Because of that the Mercury spacecraft did not require a main computer. |
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The Gemini spacecraft was designed to be an enlarged Mercury, performing the same general objectives. One of the largest changes to the craft was the addition of a second crew member (] in latin means "twin"). Another change is the orbital maneuvering system which was attached to the rear of the main cabin which made it possible to practice rendezvous techniques. |
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The Gemini Guidance Computer was added to the craft to fulfill the new requirements for the spacecraft which included added accuracy to re-entry and automate preflight checkout functions. The computer was also required for many of the rendezvous operations since the ground tracking network could not cover all possible orbital paths. |
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== Functionality == |
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== Functionality == |
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The Gemini Guidance Computer was responsible for the following functions:<ref name="ibm" /><ref name="manual">McDonnell Corporation, NASA Project Gemini Familiarization Manual, 1965, vol. 2, pp. 8.7,8.45.</ref> |
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] was the first with an on-board computer, as ] was controlled by computers on Earth.<ref>{{cite book |
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| last1 = Tomayko |
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| first1 = James E. |
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| year = 1988 |
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| title = Computers in Spaceflight: The NASA Experience |
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| chapter = The Gemini Digital Computer: First Machine in Orbit |
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| publisher = National Aeronautics and Space Administration |
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| location = Washington, D.C. |
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| url = https://history.nasa.gov/computers/ch1-1.html |
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| accessdate = 2015-01-04 |
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}}</ref> The Gemini Guidance Computer was responsible for the following functions:<ref name="ibm" /><ref name="manual">McDonnell Corporation, NASA Project Gemini Familiarization Manual, 1965, vol. 2, pp. 8.7,8.45.</ref> |
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* Ascent - serves as a backup ]. The switchover is manually controlled by the astronauts |
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* ''Ascent ''– serves as a backup ]. The switchover is manually controlled by the astronauts |
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* Orbital flight - provides a navigation capability to the astronauts to determine the time of retrofire and to select the landing site for safe reentry in the case of an emergency. (on extended missions ground data may become unavailable when ground data network rotates out of the ].) |
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* ''Orbital flight'' – gives the astronauts the capacity to navigate, allowing them to choose a safe landing spot in an emergency and calculate the timing of retrofire (on extended missions ground data may become unavailable when ground data network rotates out of the ]). |
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* Rendezvous - serves as primary reference by providing guidance information to the astronauts. The orbit parameters are determined by the ground tracking which are then sent to the spacecraft; the guidance computer was responsible for processing the information along with sensed spacecraft attitude. The information was presented to the astronauts in terms of spacecraft coordinates. |
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* ''Rendezvous ''– serves as primary reference by providing guidance information to the astronauts. The orbit parameters are determined by the ground tracking which are then sent to the spacecraft; the guidance computer was responsible for processing the information along with sensed spacecraft attitude. The information was presented to the astronauts in terms of spacecraft coordinates. |
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* Reentry - feeds commands directly to the reentry control system for automatic reentry or provides the guidance information to the astronauts a manual reentry. |
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* ''Reentry ''– feeds commands directly to the reentry control system for automatic reentry or provides the guidance information to the astronauts for manual reentry. |
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== Specs == |
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== Specs == |
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* The computer, which was very similar to the ], weighted 58.98 pounds (26.75 kg) and was powered by a 28V ]. During a short power outage it could be powered by the Auxiliary Computer Power Unit (ACPU) |
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* The computer was architecturally similar to the ], in particular in the instruction set;<ref name="Gemini_2011"/> however its circuit integration was less advanced.<ref></ref> The GGC weighed 58.98 pounds (26.75 kg) and was powered by 28V ]. During a short power outage it could be powered by the Auxiliary Computer Power Unit (ACPU) |
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* ] words memory, each composed of three ]s<ref name="Gemini_2011">{{cite web |title=Gemini Spacecraft Computer (OBC): Layout of Memory Words |date=2016 |orig-year=2011 |url=http://www.ibiblio.org/apollo/Gemini.htp |access-date=2016-05-28 |url-status=live |archive-url=https://web.archive.org/web/20160528114015/http://www.ibiblio.org/apollo/Gemini.htp |archive-date=2016-05-28}}</ref> |
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* 39-bit words memory, each composed of three 13-bit "syllables" |
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* ferrite core memory of 4096 words<ref>, chapter one</ref> |
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* ] memory of 4,096 words<ref>, chapter one</ref> |
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* Two's complement integer arithmetic |
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* Two's complement integer arithmetic |
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* 7.143 kilohertz clock (140 μs per instruction); all instructions took a single cycle except for multiplication and division |
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* 7.143 kilohertz clock (140 μs per instruction); all instructions took a single cycle except for multiplication and division |
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==See also== |
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* ] |
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== References == |
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== References == |
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== External links == |
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== External links == |
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{{Commons category|Gemini Guidance Computer}} |
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{{CCBYSASource|sourcepath=http://en.wikichip.org/Gemini_Guidance_Computer|sourcearticle=Gemini Guidance Computer|revision=653091201}} |
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{{Gemini program}} |
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{{Guidance Computer}} |
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{{CPU technologies}} |
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.JPG)
Gemini Guidance Computer in National Air and Space Museum
Category:Guidance computers