The Xerox 500 series was a line of computers from
Xerox Data Systems
Scientific Data Systems (SDS), was an American computer company founded in September 1961 by Max Palevsky and Robert Beck, veterans of Packard Bell Corporation and Bendix, along with eleven other computer scientists. SDS was an early adopter of ...
(XDS) introduced in the early 1970s as
backward-compatible
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially i ...
upgrades for the
Sigma series machines.
Although orders for the Xerox 530 were deemed "encouraging" as of January 1974,
the systems had failed to gain traction by the time Xerox sold its Data Systems Division in 1975. The buyer,
Honeywell, Inc., continued to support existing 500-series systems until 1984 but discontinued manufacturing.
Binary integer arithmetic was standard on all models;
floating-point
In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can b ...
was optional on the 530, and standard on the 550 and 560. The 560 also supported
decimal arithmetic
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 of the Hindu–Arabic numeral ...
. The 550 and 560 included one or more "system control processors" (CPs) to handle interrupts, diagnostics, clocks, direct I/O, and operator communications. Systems were clusterable, with multiple "basic processors" (BPs), I/O processors (IOPs), and "system control processors" (CPs) sharing
busses
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for char ...
and memory.
16 bit systems (Xerox 530)
The Xerox 530 system was a
16-bit
16-bit microcomputers are microcomputers that use 16-bit microprocessors.
A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...
computer aimed at upgrading the 16-bit Sigma 2 and 3 systems. The 530 was the first system of the line introduced in early 1973.
The 530 supported memory sizes of 8 K to 64 K 16-bit words (16 KB to 128 KB) with a cycle time of 800 ns.
The memory protection feature protected the foreground (real-time) program from the background tasks.
When IBM dropped the 16-bit
IBM 1130
The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding th ...
, Xerox began marketing the 530 as a possible successor,
including mention of COBOL and RPG.
[ Both the 1130 and Xerox 530 had Indirect addressing and 8-bit relative addressing.
On the IBM 1130/1800 ]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 were only available as a special feature—RPQ (Request Price Quotation). The Xerox 530 offered a choice of a 7-track drives operating at 37.5 inches per second (ips) or nine-track, 75 ips drives.
32 bit systems (Xerox 550, 560)
The Xerox 550 and Xerox 560 systems were 32-bit
In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...
computers introduced in 1974. The 550 was aimed at real-time
Real-time or real time describes various operations in computing or other processes that must guarantee response times within a specified time (deadline), usually a relatively short time. A real-time process is generally one that happens in defined ...
applications and intended as an upgrade for the Sigma 5. The 560 was aimed at the general-purpose Sigma 6, 7, and 9 upgrade market.
The systems were microprogrammed and constructed using large-scale and medium-scale integration (LSI and MSI) and magnetic-core memory
Magnetic-core memory was the predominant form of random access, random-access computer memory for 20 years between about 1955 and 1975.
Such memory is often just called core memory, or, informally, core.
Core memory uses toroids (rings) of a ...
.Virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
and memory protection were standard features.
A 590 system was designed but never built.
Operating systems
The 530 could run either the ''Basic Control Monitor'' (BCM) or the ''Real-time Batch Monitor'' (RBM) operating systems.[
RBM could run a combination of real-time and general-purpose batch jobs running at the same time.]CP-V
The Universal Time-Sharing System (UTS) is a discontinued operating system for the XDS Sigma series of computers, succeeding Batch Processing Monitor (BPM)/Batch Time-Sharing Monitor (BTM). UTS was announced in 1966, but because of delays did no ...
operating system.
Much as IBM's Job Control Language was known for its "//" (Slash-Slash), Xerox's used an exclamation point, which it called "Bang."
References
{{Reflist
External links
Photo of a Xerox 530 system with tape drive and printer
Computer-related introductions in 1973
Computer-related introductions in 1974
Mainframe computers
Minicomputers
500 series
32-bit computers