Equipment MIT selected IBM as the prime contractor for equipment construction. The Central Computer System of the AN/FSQ-7 had two computers for redundancy each with Arithmetic, Core Memory, Instruction Control, Maintenance Control, Selection & IO Control, and Program elements. The Q7 had input/output devices such as: IBM 723 card punch and IBM 713 punched card reader IBM 718 line printer (64 print positions) drum auxiliary memory (50 "fields" of 2048 words each) and IBM 728 magnetic tape drives (32-bit words) Crosstelling Input (XTL) from other AN/FSQ sites Display and Warning Light System with dozens of consoles in various rooms having Situation Display Tubes, Digital Display Tubes, and controls (e.g., push buttons and light gun) including: Duplex Maintenance Console (two), each DMC operated one of the Central Computer Systems and allowed diagnostics (a speaker was available) Tracker Initiator Consoles for designating a "blip" (radar return) to be tracked (assign a track number and to relay speed, direction, and altitude) Command Post Digital Display Desk Senior Director's keyed console with the Bomarc fire button LRI Monitor Console for monitoring Long Range Radar data Large Board Projection Equipment Operator displays were directly copied on 35 mm film which were projected on the board. Punched card data was transferred to and from the core memory as binary images. Only the rightmost 64 columns were transferred, with each row containing two 32-bit words. (The left columns could be punched using a special instruction.) Data were transferred to the line printer as a card image as well. Core memory element The FSQ-7 and -8 used core memory with 32-bit words plus a parity bit, operating at a 6-microsecond cycle time. Both machines had two banks of memory, memory 1 and memory 2 (Commonly referred to as Big Mem and little Mem). On the FSQ 7 memory 1 had 65,536 words and memory 2 had 4096 words. At Luke Air Force Base, the FSQ-7 held 65,536 words at each bank and the FSQ-8 4096 words at each bank. For data storage, each word was divided into two halves, each half was a 15-bit number with a sign bit. Arithmetic operations were performed on both halves simultaneously. Each number was treated as a fraction between −1 and 1. This restriction is placed on data primarily so that the multiplication of two numbers will always result in a product smaller than either of the numbers, thus positively avoiding overflow.