During a Gemini flight, five IBM computers in Houston,
Texas, performed 25 billion calculations every 24 hours
to provide NASA flight controllers with almost instantaneous
reports on the moment-by-moment progress of the mission.
The IBM Federal Systems Division's Space Guidance Center
in Owego, N.Y., also designed and built a special onboard
guidance computer for the
Gemini astronauts that performed complex calculations
to help them guide and maneuver their spacecraft.
The computer weighed approximately 59 pounds, performed
more than 7,000 calculations a second, and needed no more
room than a hatbox — 1.35 cubic feet — aboard
the Gemini. It had an average power consumption of 94.54
watts, a 500 kc bit rate, a memory cycle time of 250 kc
and an add time of 140 microseconds. The computer's memory
was a random-access, nondestructive readout design with
flexible instruction and data storage organization. Its
nominal capacity was 4,096 39-bit words and its operational
capacity was 12,288 13-bit words.
In simple terms, the computer accepted data either from
gyros and similar onboard systems, from the astronauts
and from ground control systems, then computed and reported
navigation and control information to the two astronauts.
During ascent and reentry, the IBM computer could also
issue steering signals to control the flight path.
By the end of the Gemini program in 1966, IBM's guidance
computer aided in the accomplishment of these space firsts:
 |
First maneuvers by an orbiting spacecraft. |
| · |
First rendezvous in space. |
|
First docking in space. |
|
First navigation in space. |
|
First rendezvous in initial orbit. |
|
First onboard computer controlled reentry. |
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