The NCR 315 Data Processing System, released in January 1962 by NCR, is a

second-generation Second generation or variants may refer to: * Second generation immigrant ** Nisei, one of the second generation of people of Japanese descent in the Americas * Second generation of Chinese leaders, see Generations of Chinese leadership * Second-ge ...

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

. All

printed circuit board A printed circuit board (PCB), also called printed wiring board (PWB), is a Lamination, laminated sandwich structure of electrical conduction, conductive and Insulator (electricity), insulating layers, each with a pattern of traces, planes ...

s use

resistor–transistor logic Resistor–transistor logic (RTL), sometimes also known as transistor–resistor logic (TRL), is a class of digital circuits built using resistors as the input network and bipolar junction transistors (BJTs) as switching devices. RTL is the earlies ...

(RTL) to create the various logic elements. It uses

12-bit Before the widespread adoption of ASCII in the late 1960s, six-bit character codes were common and a 12-bit word, which could hold two characters, was a convenient size. This also made it useful for storing a single decimal digit along with a si ...

''slab'' memory structure using

magnetic-core memory In computing, magnetic-core memory is a form of random-access memory. It predominated for roughly 20 years between 1955 and 1975, and is often just called core memory, or, informally, core. Core memory uses toroids (rings) of a hard magneti ...

. The instructions can use a memory slab as either two 6-bit alphanumeric characters or as three

4-bit 4-bit computing is the use of computer architectures in which integer (computer science), integers and other data (computer science), data units are 4 bits wide. 4-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures a ...

BCD BCD may refer to: Computing * Binary-coded decimal, a representation of decimal digits in binary ** BCD (character encoding), a 6-bit superset of binary-coded decimal derived from the binary encoding of the same name * Boot Configuration Data, th ...

digits. Basic memory is 5000 "slabs" (10,000 characters or 15,000 decimal digits) of handmade core memory, which is expandable to a maximum of 40,000 slabs (80,000 characters or 120,000 decimal digits) in four

refrigerator A refrigerator, commonly shortened to fridge, is a commercial and home appliance consisting of a thermal insulation, thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to ...

-size cabinets. The main processor includes three cabinets and a console section that houses the power supply, keyboard, output writer (an

IBM electric typewriter The IBM Electric were an early series of electric typewriters that IBM manufactured, starting in the mid-1930s. They used the conventional moving carriage and typebar mechanism, as opposed to the fixed carriage and type ball used in the IBM Sel ...

), and a

panel Panel may refer to: Arts and media Visual arts *Panel painting, in art, a painting on a wood panel (as opposed to canvas, a wall etc) *Panel (comics), a single image in a comic book, comic strip or cartoon; also, a comic strip containing one ...

with lights that indicate the current status of the program counter, registers, arithmetic accumulator, and system errors. Input/Output is by direct

parallel connection Two-terminal components and electrical networks can be connected in series or parallel. The resulting electrical network will have two terminals, and itself can participate in a series or parallel topology. Whether a two-terminal "object" is ...

s to each type of peripheral through a two-cable bundle with 1-inch-thick cables. Some devices like

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic ...

and the

CRAM Cram may refer to: * Cram (surname), a surname, and list of notable persons having the surname * Cram.com, a website for creating and sharing flashcards * ''Cram'' (Australian game show), a television show * ''Cram'' (game show), a TV game show ...

are daisy-chained to allow multiple drives to be connected. The central processor (315 Data Processor) weighed about . Later models in this series include the 315-100 and the 315-RMC (Rod Memory Computer).

Memory organization

The addressable unit of memory on the NCR 315 series is a "slab", short for "syllable", consisting of 12 data

bit The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...

s and a

parity bit A parity bit, or check bit, is a bit added to a string of binary code. Parity bits are a simple form of error detecting code. Parity bits are generally applied to the smallest units of a communication protocol, typically 8-bit octets (bytes) ...

. Its size falls between a

byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...

and a typical

word A word is a basic element of language that carries semantics, meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consensus among linguist ...

(hence the name, '

syllable A syllable is a basic unit of organization within a sequence of speech sounds, such as within a word, typically defined by linguists as a ''nucleus'' (most often a vowel) with optional sounds before or after that nucleus (''margins'', which are ...

'). A slab may contain three digits (with

at sign The at sign () is an accounting and invoice abbreviation meaning "at a rate of" (e.g. 7 Widget (economics), widgets @ £2 per widget = £14), now seen more widely in email addresses and social media platform User (computing), handles. It is norm ...

comma The comma is a punctuation mark that appears in several variants in different languages. Some typefaces render it as a small line, slightly curved or straight, but inclined from the vertical; others give it the appearance of a miniature fille ...

space Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...

ampersand The ampersand, also known as the and sign, is the logogram , representing the grammatical conjunction, conjunction "and". It originated as a typographic ligature, ligature of the letters of the word (Latin for "and"). Etymology Tradi ...

, point, and

minus The plus sign () and the minus sign () are mathematical symbols used to denote positive and negative functions, respectively. In addition, the symbol represents the operation of addition, which results in a sum, while the symbol represent ...

treated as digits) or two alphabetic characters of six bits each. A slab may contain a

decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers (''decimal fractions'') of th ...

value from -99 to +999. A numeric value contains up to eight slabs. If the value is negative then the minus sign is the leftmost digit of this row. There are instructions to transform digits to or from alphanumeric characters. These commands use the accumulator, which has a maximum length of eight slabs. To accelerate the processing the accumulator works with an effective length.

NCR 315-100

The NCR 315-100 is the second version of the original 315. It too has a 6-

microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is to one second, ...

clock cycle, and from 10,000 to 40,000 slabs of memory. The 315-100 series console I/O incorporates a

Teletype A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Init ...

printer and keyboard in place of the original 315's IBM typewriter. The primary difference between the older NCR 315 and the 315-100 was the inclusion of the Automatic Recovery Option (ARO). One of the problems with early generation of computers was that when a memory or program error occurred, the system would simply turn on a red light and halt. The normal recovery process was to copy all register and counter setting from the console light panel, and to restart the program that was running at the time of the error, usually from the very beginning of the program. The upgrade to the 315 required the removal of approximate 1800

wire-wrap Close-up of a wire-wrap connection Typical wire wrap construction of crossbar_switch.html" ;"title="Bell System telephone crossbar switch">Bell System telephone crossbar switch. Some types of connection were soldered. Wire wrap is an electron ...

ped connection on the backplane, and the installation of approximately 2400 new point-to-point wired connection.

NCR 315-RMC

The NCR 315-RMC, released in July 1965, was the first commercially available computer to employ

thin-film memory Thin-film memory is a high-speed alternative to magnetic-core memory developed by Sperry Rand in a government-funded research project. Instead of threading individual ferrite cores on wires, thin-film memory consisted of 4-micrometer thick do ...

. This reduced the clock cycle time to 800

nanosecond A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit (e ...

s. It also included

floating-point In computing, floating-point arithmetic (FP) is arithmetic on subsets of real numbers formed by a ''significand'' (a Sign (mathematics), signed sequence of a fixed number of digits in some Radix, base) multiplied by an integer power of that ba ...

logic to allow scientific calculations, while retaining the same instruction set as previous NCR 315 and NCR 315-100. The thin film is wrapped around "rods" to allow faster reading and writing of memory. The follow-on to the 315-RMC was the NCR Century series.

Available languages

* NCR Assembler Language * National Electronic Autocoding Technique (NEAT) — similar to

Autocoder Autocoder is any of a group of assemblers for a number of IBM computers of the 1950s and 1960s. The first Autocoders appear to have been the earliest assemblers to provide a macro facility. Terminology Both ''autocoder'', and the unrelated '' ...

COBOL COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural, and, since 2002, object-oriented language. COBOL is primarily ...

* BEST, a high-level preproocesor for NEAT

Available peripherals

* NCR-321 Communications Controller * NCR-340 600-LPM line printer *

Magnetic tapes Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magneti ...

** NCR-332 Magnetic tape drive (512 bpi) ** NCR-333 Control Data

CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under the Department of Health and Human Services (HHS), and is headquartered in Atlanta, ...

tape drive (512 bpi) ** NCR-334 Magnetic Tape Drive (200/512 bpi) * NCR-353 Magnetic Card Random Access Memory (

) *

Card Card or The Card may refer to: Common uses * Plastic cards of various types: **Bank card **Credit card **Debit card **Payment card * Playing card, used in games * Printed circuit board, or card * Greeting card, given on special occasions Arts an ...

and

paper tape Five- and eight-hole wide punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data st ...

equipment ** NCR-361 Paper Tape Reader ** NCR-371 Paper Tape Punch ** NCR-376

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

Card Reader/Punch ** NCR-380 2000 CPS High speed card reader ** NCR-472 Card Reader, Paper Tape Reader/Punch * NCR-???

Drum memory Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. Many early computers, called drum computers or drum machines, used drum ...

* NCR-402

MICR Magnetic ink character recognition code, known in short as MICR code, is a character recognition technology used mainly by the banking industry to streamline the processing and clearance of cheques and other documents. MICR encoding, called the ...

Check Reader/Sorter * NCR-420 Optical Character Reader ( OCR) * NCR-407 High Speed MICR Check Reader/Sorter

References

External links

Rod Memory description
* {{DEFAULTSORT:Ncr 315 Mainframe computers Transistorized computers Decimal computers 12-bit computers NCR Corporation products