CDC 1604

The CDC 1604 was a 48-bit computer designed and manufactured by Seymour Cray and his team at the Control Data Corporation. The 1604 is known as the first commercially successful transistorized computer. The 1604 designation was chosen by adding CDCs first street address (501) to Cray's former project, the 1103. A cut-down 24-bit version, designated the CDC 924, was also produced.

The first 1604 was delivered to the US Navy in 1960 for applications supporting major Fleet Operations Control Centers in Hawaii, London, and Norfolk, Virginia. By 1964, over 50 systems were built. The CDC 3000 succeeded the 1604.

A 12-bit minicomputer, called the CDC 160A, was often used as an I/O processor in 1604 systems. The CDC-160A is, arguably, the first minicomputer.

Architecture

Memory in the CDC 1604 consisted of 32K 48-bit words of magnetic core memory with a cycle time of 6.4 microseconds. It was organized as two banks of 16K words each, with odd addresses in one bank and even addresses in the other. The two banks were phased 3.2 microseconds apart, so average effective memory access time was 4.8 microseconds.

Each 48-bit word contained two 24-bit instructions. The instruction format was 6-3-15: 6 bits for the operation code, 3 bits for a "designator" (index register for memory access instructions, condition for jump instructions) and 15 bits for a memory address (or shift count, for shift instructions).

Trivia

NAVCOSSACT based at the Washington Navy Yard provided systems and training support.
JOVIAL was used as the CDC 1604's main programming language while octal was used to program shared services supported by the CDC 160A.

During 1969, Fleet Operations Control Center, Pacific (FOCCPAC at Kunia) on Oahu in Hawaii launched an "Automated Control Environment" (ACE) using a cluster of five (5) CDC 160As to supervise a multi-tasking network of four (4) CDC 1604's.

The third version of the PLATO computer-based educational system was implemented on a CDC-1604.