The NCR Century 100 was
NCR's first all integrated circuit computer built in 1968.
All logic gates were created by wire-wrapping
NAND gate
In digital electronics, a NAND gate (NOT-AND) is a logic gate which produces an output which is false only if all its inputs are true; thus its output is complement to that of an AND gate. A LOW (0) output results only if all the inputs to the ...
s together to form flip-flops and other complex circuits. The console of the system had only 18 lights and switches and allowed entry of a boot routine, or changes to loaded programs or data in memory. A typewriter console was also available.
Peripherals
The 615-100 Series integrated a complete data processing system that had 16KB or 32KB of short rod memory, an 80-column
punched card reader
A computer punched card reader or just computer card reader is a computer input device used to read computer programs in either source or executable form and data from punched cards. A computer card punch is a computer output device that punches ...
or
paper tape reader, two 5MB removable
disk drives
Data storage is the recording (storing) of information (data) in a storage medium. Handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA and DNA are conside ...
, and a 600-line-per-minute
line printer
A line printer prints one entire line of text before advancing to another line. Most early line printers were
impact printers.
Line printers are mostly associated with unit record equipment and the early days of digital computing, but the ...
. The system could be provided with a punched paper tape reader, or an external card reader/punch, and also allowed for the attachment of multiple 9-track, 1/2-inch, reel-to-reel
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 magne ...
drives. Two more disk drives could be attached to the system.
The Century series used an instruction set with two instruction lengths: 4 bytes (32 bits) and 8 bytes (64 bits).
Rod memory
The memory of the Century Series computers used machine-made, short, iron-oxide-coated ceramic rods— long and approximately the diameter of a human hair— as their random access memories, instead of the hand-labor-intensive
core memories that were used by other computers of the time. The economy of machine assembly was augmented by selling rod memory without paying patent royalties on core memory to NCR's competitor,
IBM. Each 16K memory module consisted of two stacks, each stack containing sixteen planes of 4608 rods.
Disk drives
The Model 655 disk drive used a removable disk pack. It was the first by NCR to employ floating or ''flying'' heads with 12 read/write heads per surface.
["NCR REGISTERS INCREASED PRODUCTION, SALES, GETS INTO EDP MAINSTREAM," Datamation, August 1969, p.111] This reduced track-to-track movement and thus access times. However, this meant that there were 12 times more heads per drive, increasing the likelihood of head crashes. These flying heads were moved using a 16 position magnetic actuator. The actuator used four different magnets to create the 16 positions. The magnetic actuators were later replaced with hydraulic actuators, and later yet the hydraulic actuators were replaced with
voice coil
A voice coil (consisting of a former, collar, and winding) is the coil of wire attached to the apex of a loudspeaker cone. It provides the motive force to the cone by the reaction of a magnetic field to the current passing through it. The term ...
actuators. In 1972 NCR sold its disk drive business to
Magnetics Peripherals, Inc., a joint venture with CDC and thereafter used disk drives from the joint venture.
Programming languages
The NCR Century 100 supported several
programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
s: NEAT/3 (National's Easy Auto-coding Technique, a later version of the NEAT/1 language that ran on the
NCR 315
The NCR 315 Data Processing System, released in January 1962 by NCR, is a second-generation computer. All printed circuit boards use resistor–transistor logic (RTL) to create the various logic elements. It uses 12-bit ''slab'' memory structur ...
computer system),
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 us ...
,
FORTRAN, and
BASIC
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
.
Hardware
The system had 39 hardware instructions. Early versions of the hardware did not have hardware multiply or divide instructions; they were instead emulated using software. The machine used
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
8-bit code. It also supported
packed decimal
In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for ...
fields with or without a "sign". Without a sign, a (positive) number could be stored in just two bytes, with each of the 8 bits of the character holding 2 digits, such as 0001 0010 0011 0100 for 1234.
A typical hardware configuration consisted of a panel with toggle switches and lights to enter the boot loader, a Teletype writer to input operating system commands, a punched card reader that gravity feed the cards (they dropped into the read station, and were ejected and turned 180 degrees and then placed in the exit hopper), two 655 disk drives, and a printer that printed about 600 lines per minute. The boot loader and peripherals were usually on punched cards, which notified the operating system which devices to use via a PAL (Peripheral Availability List) entry cards. The "go" command to the operating system was infamous: "EE" control-G (bell).
The Century 100 lacked hardware
sense switch
A sense switch, or program switch, is a switch on the front panel of a computer whose state can be tested by conditional branch instructions in software.Rudolf F. Graf ''Modern dictionary of electronics seventh edition'', Newnes, 1999 Most early ...
es, which the Century 200 had. Programs that attempted to access sense switches on the Century 100 would simply halt with the humorous message: "You find the switches, and I'll test them!" displayed on the console typewriter.
A unique feature of the Century's hardware/software design allowed the normal 4K executive to be reduced to a mere 512 bytes, freeing up precious storage.
The Century 50 was slower than the Century 100 and only had 16K of the thin film rod memory.
References
External links
''NCR Century 100 Processor'' —NCR reference manual (1970)
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{{DEFAULTSORT:Ncr Century 100
Mainframe computers
NCR Corporation products