Experimental SAGE Subsector

For the subsequent computer system with different peripherals and IBM's Kingston XD-2 computer; and for the late 1960s system for discerning incoming ICBM warheads, see AN/FSQ-7 and Lexington Discrimination System.

The Experimental Semi-Automatic Ground Environment (SAGE) Sector (ESS, Experimental SAGE Subsector^[1] until planned Sectors/Subsectors were renamed NORAD Regions, Divisions, and Sectors)^[2] was a prototype Cold War Air Defense Sector for developing the Semi Automatic Ground Environment. The Lincoln Laboratory control center in a new building^[3] was at Lexington, Massachusetts.

ESS Computer System

The network's Direction Center was completed in a new 1954 building^[3] (Building F,^[4] 42°27′37″N 071°16′04″W^[5]) with prototype peripherals and a single IBM XD-1 computer,^[6] a successor to Lincoln Lab's Whirlwind I computer (WWI).^[7] In 1955, Air Force personnel began IBM training at the Kingston, New York, prototype facility,^[8] and the "4620th Air Defense Wing (experimental SAGE) was established^[when?] at Lincoln Laboratory"—its "primary mission was computer programming".^[9]

ESS had a capacity of 48 tracks and used a pre-SAGE ground environment in a "prototype intercept monitor room [at] MIT's Barta building" with "track situation displays, which geographically showed Air Defense Identification Zone lines and antiaircraft circles [and] each console also had a 5-inch CRT for digital information display. Audible alert signals were used, with a different signal for each symbol on a situation display."^[10]

Radar stations

Initial service test models of the Burroughs AN/FST-2 Coordinate Data Transmitting Set were placed with radars at South Truro and West Bath, Maine; followed by Texas Tower#2 (TT2) in the Atlantic Ocean, which provided a "triangular pattern with overlap" radar coverage^[11] (TT2 later had a connection from the XD-1 via the GE G/A Data Link Output Subsystem through North Truro Air Force Station.)^[12] By August 1955, 13 radar stations were networked by the subsector,^[10] e.g.:

• Chatham^[13]
• Clinton, Massachusetts with gap-filler radar^[14]
• Great Boars Head^[15]
• Halibut Point^[16]
• Killingly, Connecticut (41.865734°N 71.820958°W / 41.865734; -71.820958).with gap-filler radar^[17]
• Rockport Air Force Station
• Scituate, Massachusetts^[18]
• South Truro^[19]
• West Bath, Maine (43°54′7″N 69°50′43″W) with AN/FPS-31^[20] on Jug Handle Hill:^[21] ("Lincoln Laboratories experimental radar station")^[22]

Required by 21 November 1955 were 44 consoles: 38 for the operations floor, 3 on the computer floor for display maintenance, and 3 near the maintenance console (program checkout).^[23] WWI was connected to the Experimental SAGE Subsector to verify crosstelling (collateral communication) with the ESS DC, and WWI was also used for a Ground-to-Air (G/A) experiment using a transmitter of the GE G/A Data Link Output Subsystem on Prospect Hill, Waltham, MA sending data to simulated airborne equipment at Lexington.^[12] Transmissions from the WWI SAGE Evaluation (WISE) computer system^[3] to XD-1 and back were without error by December 1955^[3] when operational software specifications were frozen.^[24] Operating procedures for the ESS external sites were complete in March 1956,^[25] and

System Operation Testing

From November 15, 1955, to November 7, 1956, three System Operation Tests were conducted^[10] which used voice "Ground-to-Air" communication from the Barta control room to aircraft outfitted with SAGE receivers^[26] (F-86 interceptors modified to F-86L models in "Project FOLLOW-ON".)^[27] Test teams included employees of Bell Telephone Laboratories, Western Electric-ADES, IBM, the RAND Corporation, and Lincoln Labs' Division 6, Division 3, & Division 2^[4] (Division 6 had been created for ESS support.)^[28]

The North Truro P-10 AN/FST-2 was moved to Almaden Air Force Station (M-96)c. 1957-8^[27] and on August 7, 1958, control of an airborne BOMARC missile that had malfunctioned transferred from the "Experimental SAGE Sector" to a Westinghouse AN/GPA-35 Ground Environment system^[where?] and the missile crashed into the Atlantic Ocean.^[29] By December 31, 1958, ADC Manual 55-28 described the Model 3 SAGE System.^[30]

External images
Military operators at ESS consoles
""Prototype intercept monitor room in the SAGE direction center in MIT's Barta building." [dated February 19, 1955 at archive[dot]today[slash]tPdY2]

1959 Experimental Testing

"To prove out the revised SAGE computer program" for Automatic Targeting and Battery Evaluation and ADDC-AADCP crosstelling, a "SAGE/Missile Master" test was conducted beginning in September 1959 with communications between the ESS XD-1 and Martin AN/FSG-1 Antiaircraft Defense System equipment at Fort Banks^[31] planned for the CONAD Joint Control Center at Fort Heath^[32]—a "SAGE ATABE Simulation Study" (SASS) was also completed 1959–60 by MITRE Corporation.^[33]