Slab (unit)

The NCR 315 Data Processing System, released in January 1962 by NCR, was a second-generation computer. All printed circuit boards used resistor-transistor logic to create the various logic elements. It used 12-bit slab memory structure using core memory. The instructions could use a memory slab as either two 6-bit alphanumeric characters or as three 4-bit BCD characters. Basic memory was 5000 "slabs" of handmade core memory, which was expandable to a maximum of 40,000 slabs in four refrigerator-size cabinets. The main processor included three cabinets and a console section that housed the power supply, keyboard, output writer (an IBM electric typewriter), and a panel of lights that indicated the current status of the program counter, registers, arithmetic accumulator, and system errors. Input/Output was by direct parallel connections to each type of peripheral through a two-cable bundle with 1-inch-thick cables. Some devices like magnetic tape and the CRAM were daisy-chained to allow multiple drives to be connected.

Later models in this series include the 315-100 and the 315-RMC (Rod Memory Computer).

The addressable unit of memory on the NCR 315 series is a "slab", short for "syllable", consisting of 12 data bits and a parity bit. Its size falls between a byte and a typical word (hence the name, 'syllable'). A slab may contain three digits (with at sign, comma, space, ampersand, point, and minus treated as digits) or two alphabetic characters of six bits each. A slab may contain a decimal value from -99 to +999.

...
Wikipedia