MIL-STD-1750A or 1750A is the formal definition of a 16-bit computer
instruction set
In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ' ...
architecture (ISA), including both required and optional components, as described by the
military standard
In military organizations, the practice of carrying colours (or colors), standards, flags, or guidons, both to act as a rallying point for troops and to mark the location of the commander, is thought to have originated in Ancient Egypt som ...
document MIL-STD-1750A (1980). Since August 1996, it has been inactive for new designs.
In addition to the core ISA, the definition defines optional instructions, such as a
FPU and
MMU. Importantly, the standard does not define the implementation details of a 1750A processor.
Internals
The 1750A supports 2
16 16-bit words of memory for the core standard. The standard defines an optional
memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
that allows 2
20 16-bit words of memory using 512 page mapping registers (in the I/O space), defining separate instruction and data spaces, and keyed memory access control.
Most instructions are 16 bits, although some have a 16-bit extension. The standard computer has 16 general purpose 16-bit registers (0 through 15). Registers 1 through 15 can be used as
index register
An index register in a computer's CPU is a processor register (or an assigned memory location) used for pointing to operand addresses during the run of a program. It is useful for stepping through strings and arrays. It can also be used for hol ...
s. Registers 12 through 15 can be used as base registers.
Any of the 16 registers can be used as a
stack pointer for the SJS and URS instructions (''stack jump subroutine'' and ''unstack return subroutine''), but only register 15 is used as the stack pointer for the PSHM and POPM instructions (''push multiple'' and ''pop multiple'').
The computer has instructions for 16, and 32-bit binary arithmetic, as well as 32 and 48 bit
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 be ...
. I/O is generally via the I/O instructions (XIO and VIO), which have a separate 2
16 16-bit word address space and may have a specialized bus.
Implementations
![MIL STD P1750AE40PGME 1](https://upload.wikimedia.org/wikipedia/commons/8/88/MIL_STD_P1750AE40PGME_1.jpg)
Because MIL-STD-1750A does not define implementation details, 1750A products are available from a wide variety of companies in the form of component, board, and system-level offerings implemented in myriad technologies, often the most advanced and exotic of their respective periods (e.g.
GaAs
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a zinc blende crystal structure.
Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circui ...
,
ECL,
SoS).
1750A systems often offer high levels of protection from radiation and other hazardous environments, making them particularly suited for military, aviation and space applications.
Examples of MIL-STD-1750A implementations include:
*
CPU Technology, Inc. CPU1750A-FB, a high performance 1750A
SOC designed to give existing applications a late life performance boost.
*
Delco Systems Operations Magic V 1750 Processor
*
Dynex Semiconductor
Dynex Semiconductor based in Lincoln, England, United Kingdom is a global supplier of products and services specialising in the field of power semiconductor devices and silicon on sapphire integrated circuit products. The power products they manu ...
MAS281. A
radiation hardened
Radiation hardening is the process of making electronic components and circuits resistant to damage or malfunction caused by high levels of ionizing radiation ( particle radiation and high-energy electromagnetic radiation), especially for enviro ...
SOC implementation on a 64-pin multichip module with an optional MMU.
*
GEC-Plessey RH1750, a radiation-hardened version for aerospace and space flight applications. GEC-Plessey, under its previous iteration as
Marconi Electronic Devices, also initially developed the MAS281 and MA31750A series of processors, later made available through
Dynex Semiconductor
Dynex Semiconductor based in Lincoln, England, United Kingdom is a global supplier of products and services specialising in the field of power semiconductor devices and silicon on sapphire integrated circuit products. The power products they manu ...
*
Honeywell
Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...
HX1750, fabricated on Honeywell's Silicon on Insulator CMOS (SOI-IV) process giving radiation hardness. The HX1750 includes an FPU and peripherals on chip.
* Johns Hopkins University
Applied Physics Laboratory
The Johns Hopkins University Applied Physics Laboratory (Applied Physics Laboratory, or APL) is a not-for-profit University Affiliated Research Center, university-affiliated research center (UARC) in Howard County, Maryland. It is affiliated w ...
(JHU/APL) MIL-STD-1750AAV space flight qualified processor. A multi-board
silicon on sapphire
Silicon on sapphire (SOS) is a hetero-epitaxial process for metal-oxide-semiconductor (MOS) integrated circuit (IC) manufacturing that consists of a thin layer (typically thinner than 0.6 µm) of silicon grown on a sapphire (Al2O3) wafer. ...
implementation specifically designed for space flight.
*
Marconi Electronic Devices MIL-STD-1750A.
*McDonnell-Douglas MD-281. A radiation hardened SoS three-die implementation on a 64-pin multichip module.
*
Fairchild Semiconductor
Fairchild Semiconductor International, Inc. was an American semiconductor company based in San Jose, California. Founded in 1957 as a division of Fairchild Camera and Instrument, it became a pioneer in the manufacturing of transistors and of int ...
F9450 series.
*
National Semiconductor PACE
National Semiconductor's IPC-16A PACE, short for "Processing and Control Element", was the first commercial single-chip 16-bit microprocessor, announced in late 1974. It was a single-chip implementation of their early 1973 five-chip IMP-16 archite ...
P1750A. The PACE normally runs a version of the
Data General Nova
The Data General Nova is a series of 16-bit minicomputers released by the American company Data General. The Nova family was very popular in the 1970s and ultimately sold tens of thousands of units.
The first model, known simply as "Nova", was ...
instruction set, but was adapted to run MIL-STD-1750A using new
microcode
In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a laye ...
. The family includes the P1750A CPU, the P1750AE Enhanced CPU, the P1753
Memory Management Unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
(MMU), the P1754 Processor Interface Chip (PIC) and the P1757ME Multi-Chip Module. This line was passed to
Performance Semiconductor
A performance is an act of staging or presenting a play, concert, or other form of entertainment. It is also defined as the action or process of carrying out or accomplishing an action, task, or function.
Management science
In the work place ...
and then Pyramid Semiconductor in 2003.
*
Royal Aircraft Establishment Farnborough
The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence (MoD), before finally losing its identity in mer ...
MIL-STD-1750A implementation in
AMD
Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...
2901 bit-slice
Bit slicing is a technique for constructing a processor from modules of processors of smaller bit width, for the purpose of increasing the word length; in theory to make an arbitrary ''n''-bit central processing unit (CPU). Each of these com ...
technology.
Programming
Processors based on MIL-STD-1750A are often programmed in
JOVIAL
JOVIAL is a high-level programming language based on ALGOL 58, specialized for developing embedded systems (specialized computer systems designed to perform one or a few dedicated functions, usually embedded as part of a larger, more complete dev ...
, a high-level
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 ...
defined by the
United States Department of Defense
The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national secu ...
which is derived from
ALGOL 58
ALGOL 58, originally named IAL, is one of the family of ALGOL computer programming languages. It was an early compromise design soon superseded by ALGOL 60. According to John Backus
The Zurich ACM-GAMM Conference had two principal motives in pro ...
. Later, the
Ada
Ada may refer to:
Places
Africa
* Ada Foah, a town in Ghana
* Ada (Ghana parliament constituency)
* Ada, Osun, a town in Nigeria
Asia
* Ada, Urmia, a village in West Azerbaijan Province, Iran
* Ada, Karaman, a village in Karaman Province, ...
was heavily used.
There are also
C compilers, for example Cleanscape XTC-1750A. Older versions of
GNU
GNU () is an extensive collection of free software (383 packages as of January 2022), which can be used as an operating system or can be used in parts with other operating systems. The use of the completed GNU tools led to the family of operat ...
GCC contain support for MIL-STD-1750A; it was declared obsolete in version 3.1, and removed in subsequent versions.
In addition, DDC-I provides its SCORE Integrated Development Environment (IDE) with both Ada95 and C compilers, and TADS (Tartan Ada Development System) Ada83 development environment, both targeting processors based on MIL-STD-1750A.
Deployments
The
U.S. Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...
defined the standard in order to have a common computing architecture and thereby reduce the costs of software and computer systems for all
military computing needs. This includes embedded tasks such as aircraft and missile control systems as well as more mundane general military computing needs.
The advantages of this concept are recognized outside of the USAF, and the 1750A has been adopted by other organizations such as the
European Space Agency
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (1205 ...
,
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
,
Israeli Aircraft Industries
Israel Aerospace Industries (Hebrew: התעשייה האווירית לישראל ''ha-ta'asiya ha-avirit le-yisra'el'') or IAI (תע"א) is Israel's major aerospace and aviation manufacturer, producing aerial and astronautic systems for both mi ...
, and many projects in academia.
Examples of military aircraft using the 1750A include:
*
IAI Lavi
The IAI Lavi (Hebrew: לביא, "Young Lion") was a single-engined fourth-generation multirole jet fighter developed in Israel, by Israel Aircraft Industries (IAI), during the 1980s. The decision to develop the Lavi was controversial, both with ...
fighter
*
IBM Federal Systems AP-102 Avionics Computer (used in various roles including the USAF
F-111
The General Dynamics F-111 Aardvark is a retired supersonic, medium-range, multirole combat aircraft. Production variants of the F-111 had roles that included ground attack (e.g. interdiction), strategic bombing (including nuclear weapons ca ...
avionics upgrade)
* US Army
AH-64D Apache Longbow Helicopter
* USAF
F-16
The General Dynamics F-16 Fighting Falcon is a single-engine Multirole combat aircraft, multirole fighter aircraft originally developed by General Dynamics for the United States Air Force (USAF). Designed as an air superiority day fighter, it ...
Digital Flight Control System and Fire Control Computer
* USN
F-18
The McDonnell Douglas F/A-18 Hornet is an all-weather, twin-engine, supersonic, carrier-capable, multirole combat aircraft, designed as both a fighter and attack aircraft (hence the F/A designation). Designed by McDonnell Douglas (now part ...
RFCS Flight Control Computer
Use in space
Fully space-rated implementations make the 1750A one of the few types of computers that are applicable for use in deep space applications. Example spacecraft that use the 1750A are:
*
EOS
In ancient Greek mythology and religion, Eos (; Ionic and Homeric Greek ''Ēṓs'', Attic ''Héōs'', "dawn", or ; Aeolic ''Aúōs'', Doric ''Āṓs'') is the goddess and personification of the dawn, who rose each morning from her home at ...
Aqua
Aqua is the Latin word for water. It is used in many words which relate to water, such as aquatic life. In English, it may also refer to:
Arts
* Aqua (color), a greenish-blue color
Business
* Aqua (skyscraper), an 82-story residential skysc ...
,
Aura and
Terra
Terra may often refer to:
* Terra (mythology), primeval Roman goddess
* An alternate name for planet Earth, as well as the Latin name for the planet
Terra may also refer to: Geography Astronomy
* Terra (satellite), a multi-national NASA scienti ...
* ESA
Cluster
may refer to:
Science and technology Astronomy
* Cluster (spacecraft), constellation of four European Space Agency spacecraft
* Asteroid cluster, a small asteroid family
* Cluster II (spacecraft), a European Space Agency mission to study t ...
* ESA
Envisat
Envisat ("Environmental Satellite") is a large inactive Earth-observing satellite which is still in orbit and now considered space debris. Operated by the European Space Agency (ESA), it was the world's largest civilian Earth observation satell ...
- Envisat's ASAR instrument, built by
Matra Marconi Space
Matra Marconi Space (MMS) was a Franco-British aerospace company.
History
Matra Marconi Space was established in 1990 as a joint venture between the space and telecommunication divisions of the Lagardère Group ( Matra Espace) and the GEC g ...
and comprising the Central Electronics Sub-Assembly and Antenna Sub-Assembly used a total of 42 GEC-Plessey MA31750A processors in a dual-redundant configuration
* ESA
Rosetta
Rosetta or Rashid (; ar, رشيد ' ; french: Rosette ; cop, ϯⲣⲁϣⲓⲧ ''ti-Rashit'', Ancient Greek: Βολβιτίνη ''Bolbitinē'') is a port city of the Nile Delta, east of Alexandria, in Egypt's Beheira governorate. The Ro ...
*ISRO GSAT/INSAT/IRS series of spacecraft
* ISRO Mars Orbiter Mission
* ISRO Space Recovery Experiment-1 Guidance and Navigation Computer
* Midcourse Space Experiment (MSX) spacecraft developed at JHU/APL
* MSTI-1, 2 and 3
* NASA
Cassini
* NASA Landsat 7
* NASA
Mars Global Surveyor
''Mars Global Surveyor'' (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through the a ...
* Naval Research Laboratory
Clementine
A clementine (''Citrus × clementina'') is a tangor, a citrus fruit hybrid between a willowleaf mandarin orange ( ''C.'' × ''deliciosa'') and a sweet orange (''C. × sinensis''), named in honor of Clément Rodier, a French missionary who fir ...
Lunar Orbiter
* NOAA
GOES-13, GOES-O and GOES-P
*
Orbital Sciences Corporation
Orbital Sciences Corporation (commonly referred to as Orbital) was an American company specializing in the design, manufacture, and launch of small- and medium- class space and launch vehicle systems for commercial, military and other governmen ...
commercial communication satellite platforms
*
USAF Titan-4 Guidance Computer
1750B
The MIL-STD-1750B was to be a successor architecture to the MIL-STD-1750A, with added and expanded features, some of which were optional. By the mid-1980s there was a published draft of the 1750B available,
[S. Lloyd Plehaty]
"Software Considerations for Interfacing Avionics Computers and Mux Buses"
''SAE Transactions'' Vol. 95, Section 7: Aerospace (1986), pp. 63–68. and some vendors began implementations for it. However, no finalized specification was ever issued for the 1750B, as military and industry attention shifted to 32-bit architectural alternatives such as the
MIPS R3000.
References
External links
DOD MIL-STD-1750 standardDOD MIL-STD-1750 standardPDF), with updated Notice 1, 21 May 1982
DOD MIL-STD-1750 standardHTML), with updated Notice 1, 21 May 1982
Ada83 compiler for the 1750A processorIDE, Ada95, EC++ and ANSI C compilers for the 1750A processorAda and ANSI C compilersReferences to use in spacecraft
Dynex Semiconductor MA31750 ProcessorPyramid Semiconductor P1750A-SOS Processor
{{DEFAULTSORT:Mil-Std-1750a
Instruction processing
Military computers
Avionics computers
Military of the United States standards
Radiation-hardened microprocessors
16-bit microprocessors