The Xerox 500 series is a discontinued line of computers from
Xerox Data Systems
Scientific Data Systems (SDS), was an American computer company founded in September 1961 by Max Palevsky, Arthur Rock and Robert Beck, veterans of Packard Bell Corporation and Bendix, along with eleven other computer scientists. SDS was the fir ...
(XDS) introduced in the early 1970s as
backward-compatible
In telecommunications and computing, backward compatibility (or backwards compatibility) is a property of an operating system, software, real-world product, or technology that allows for interoperability with an older legacy system, or with inp ...
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 is standard on all models;
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 ...
is optional on the 530, and standard on the 550 and 560. The 560 also supports
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 (''decimal fractions'') of the ...
. The 550 and 560 include one or more "system control processors" (CPs) to handle interrupts, diagnostics, clocks, direct I/O, and operator communications. Systems are 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 motor vehicle that carries significantly more passengers than an average car or van, but fewer than the average rail transport. It is most commonly used i ...
and memory.
16-bit systems (Xerox 530)
The Xerox 530 system is 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 ...
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 supports 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 protects the foreground (real-time) program from the background tasks.
When IBM discontinued 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 Fortan IV, 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 magnetic ...
drives were only available as a special feature—RPQ (Request Price Quotation Request price quotation or RPQ is a long-standing IBM designation for a product or component that is potentially available, but that is not on the "standard" price list. Typical RPQ offerings are custom interfaces, hardware modifications, research o ...
). The Xerox 530 offered a choice of 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 are 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 a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...
computers introduced in 1974. The 550 was aimed at real-time
Real-time, realtime, or real time may refer to:
Computing
* Real-time computing, hardware and software systems subject to a specified time constraint
* Real-time clock, a computer clock that keeps track of the current time
* Real-time Control Syst ...
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 are microprogrammed and constructed using large-scale and medium-scale integration (LSI and MSI) and 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 ...
.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 ver ...
and memory protection are standard features.
A 590 system was designed but never built.
Operating systems
The 530 can run either the ''Basic Control Monitor'' (BCM) or the ''Real-time Batch Monitor'' (RBM) operating systems.[
RBM supports a combination of real-time and general-purpose batch jobs running at the same time.]Job Control Language
Job Control Language (JCL) is a scripting language used on IBM mainframe operating systems to instruct the system on how to run a batch processing, batch job or start a subsystem. The purpose of JCL is to say which programs to run, using which fi ...
statements begin with // (Slash-Slash), Xerox uses an exclamation point (!), which it called "Bang."
References
External links
Photo of a Xerox 530 system with tape drive and printer
{{Xerox
Computer-related introductions in 1973
Computer-related introductions in 1974
Mainframe computers
Minicomputers
500 series
16-bit computers
32-bit computers