The RCA (CDP)1802 (aka RCA COSMAC*, COSMAC 1802) is an 8-bit CMOS microprocessor (µP) introduced by RCA in early 1976, and presently being manufactured by Intersil Corporation. The 1802 has an architecture quite different from most other 8-bit microprocessors. 8-bit refers to the number of bits used in the data bus of a computer. ... Static CMOS Inverter Complementary metal–oxide–semiconductor (CMOS) (see-moss, IPA: ), is a major class of integrated circuits. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... RCA, formerly an initialism for the Radio Corporation of America, is now a trademark used by two companies for products descended from that common ancestor: Thomson Consumer Electronics, which manufactures RCA-branded televisions, DVD players, video cassette recorders, direct broadcast satellite decoders, camcorders, audio equipment, telephones, and related accessories; and... Year 1976 Pick up sticks(MCMLXXVI) was a leap year starting on Thursday (link will display full calendar) of the Gregorian calendar. ... 2005 is a common year starting on Saturday of the Gregorian calendar. ... Intersil Corporation NASDAQ: ISIL produces integrated circuits and semiconductors. ...

(* COSMAC is an acronym for COmplementary Silicon Metal-oxide Conductor, which was RCA's term for its first CMOS (COS/MOS) semiconductor technology.) A semiconductor is a solid whose electrical conductivity is in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically. ...

RCA CDP1802CD microprocessor.

RCA 1802 processor [1] This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... RCA 1802 processor [1] This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ...

Introduction

The RCA 1802—which is actually the one-chip implementation of the earlier two-chip RCA 1801—has a static CMOS design with no minimum clock frequency, so that it can be run at very low speeds and low power. It has an 8-bit parallel bus with a bidirectional data bus and a multiplexed address bus (i.e., the high order byte of the 16-bit address and the low order byte of the address take turns in using the 8-bit physical address bus lines, by accessing the bus lines in different clock cycles). It has a single bit, programmable output port, and four input pins which are directly tested by branch instructions. Its I/O mode is flexible and programmable, and it has a single-phase clock with an on-chip oscillator. Its register set consists of sixteen 16-bit registers. The program counter (PC) can reside in any of these, providing a simple way to implement multiple PCs, pointers, or registers. Static CMOS Inverter Complementary metal–oxide–semiconductor (CMOS) (see-moss, IPA: ), is a major class of integrated circuits. ... In synchronous digital electronics, such as most computers, a clock signal is a signal used to coordinate the actions of two or more circuits. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers. ... An address bus is (part of) a computer bus, used by CPUs or DMA-capable units for communicating the physical addresses of computer memory elements/locations that the requesting unit wants to access (read/write). ... This article is about the unit of information. ... It has been suggested that some sections of this article be split into a new article entitled instruction set architecture. ... Energy Input: The energy placed into a reaction. ... Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ... In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values—typically, the values being in the midst of a calculation at a given point in time. ... In computer science, 16-bit is an adjective used to describe integers that are at most two bytes wide, or to describe CPU architectures based on registers, address buses, or data buses of that size. ... The program counter (also called the instruction pointer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence. ...

Applications

From the outset the 1802 has also been available fabricated in Silicon on Sapphire semiconductor process technology, which gives it a degree of resistance to radiation and electrostatic discharge (ESD). Along with its extreme low-power abilities, this makes the chip well-suited in space applications (also, at the time the 1802 was introduced, very few, if any, other radiation-hardened microprocessors were available in the market). The 1802 was used in the Voyager, Viking, and Galileo spacecraft, and has been widely used in Earth-orbiting satellites. The Voyager spacecraft have three 1802s running at 6.4 MHz. All these CPUs sent to space were operating at full military specification temperatures (-55 to +125 °C). Silicon on sapphire (SOS) is a hetero-epitaxial process for integrated circuit manufacturing that consists of a thin layer (typically thinner than 0. ... Microelectronics designed for environments with high levels of ionizing radiation have special design challenges. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Voyager Project redirects here. ... Viking mission profile. ... Galileo is prepared for mating with the IUS booster Galileo being deployed after being launched by the Space Shuttle Atlantis on the STS-34 mission Galileo was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. ... An Earth observation satellite, ERS 2 In the context of spaceflight, satellites are objects which have been placed into orbit by human endeavor. ... For the album by The Verve, see Voyager 1 (album). ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... The degree Celsius (symbol: °C) is an SI derived unit of temperature. ...

The 1802 was also used in ACAL, a microprocessor based system for the detection of gasses in chemical warfare. ACAL was designed by Oldelft / Delft Instruments, a Dutch company in the military & defence business. ACAL only got as far as prototype stage and was never made in real production. It was a complex design, based on chemical, mechanical, optical, and electronic principles. At the time of development (1980s), it was really a state of the art design, when no other detection system could meet with the specifications. One prototype seems to have gone with the Dutch Navy to the First Gulf War, but production was generally limited. The ACAL became obsolete around the end of the Cold War came, with the advent of simpler and reliable electronic detectors.

Commercial applications included the MIL Key building access control system, made in Australia, and marketed by Philips in Europe in the 1980s.

A number of early microcomputers were based on the 1802, including the Comx-35, COSMAC ELF, COSMAC VIP, ELF II, SuperELF and Yugoslav Pecom 32 and 64, as well as the RCA Studio II video game console (one of the first consoles to use bitmapped graphics). The Comx-35 was an obscure, and very simple, home computer that was one of the very few systems to use the RCA 1802 microprocessor, the same microprocessor that is also used in some space probes because it is radiation resistant. ... The COSMAC ELF was a very early personal computer. ... The RCA Cosmac VIP (1977) was an early microcomputer that was aimed at video games. ... The Netronics ELF II was an early microcomputer trainer kit introduced about 1977 featuring an RCA 1802 microprocessor, 256 bytes of RAM, 0 bytes of ROM, DMA based based bit mapped graphics, hex keypad for user interaction and DMA based program loading, a two digit hexadecimal LED display, an LED... Socialist Federal Republic of Yugoslavia (SFRY) was a communist country that existed in the second half of the 20th century. ... Pecom 32 was an educational and/or home computer developed by Elektronska Industrija Niš of Serbia in 1985. ... Pecom 64 was an educational and/or home computer developed by Elektronska Industrija Niš of Serbia in 1985. ... The RCA Studio II is a videogame console made by RCA that debuted in 1977. ... A video game console is an interactive entertainment computer or electronic device that manipulates the video display signal of a display device (a television, monitor, etc. ... For the use of the term raster in radio regulation, see frequency raster. ...

Technical description

Registers and I/O

An important feature of the 1802 is the register file of sixteen registers of 16 bits each. Using the SEP instruction, you can select any of the 16 registers to be the program counter; using the SEX instruction, you can select any of the 16-bit registers to be the index register. Register R0 has the special use of holding the memory address for the built-in DMA controller. The program counter (also called the instruction pointer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence. ... In computing, the SEX assembly language mnemonic has often been used for the Sign EXtend machine instruction found in the PDP-11 and many other computer architectures. ... An index register in a computer CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/array operations. ... Direct memory access (DMA) is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit. ...

The processor has 5 special I/O lines. There's a single Q output that can be set with the SEQ instruction and reset with the REQ instruction. There are four external flag inputs: EF1, EF2, EF3, EF4 and there are 8 dedicated branch instructions to conditionally branch based on the state of those input lines. The EF and Q lines were typically overused on RCA 1802 based hobbyist computers because of the lines' favorable handling. It was typical for the Q line to drive a status LED, a cassette interface, an RS-232 interface, and the speaker. This meant that the user could actually hear RS-232 and cassette data being transmitted. Energy Input: The energy placed into a reaction. ... “LED” redirects here. ... Typical 60-minute Compact Cassette. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ...

Subroutine calls

The processor does not have standard subroutine CALL immediate and RET instructions, though they can be emulated. The register file makes possible some interesting subroutine call and return mechanisms, though they are better suited to small programs than general purpose coding. A few commonly used subroutines can be called quickly by keeping their address in one of the 16 registers; the SEP instruction is used to call a subroutine pointed to by one of the 16 bit registers and RET to return. Before a subroutine returns, it jumps to the location immediately preceding its entry point so that after the RET instruction returned control to the caller, the register will be pointing to the right value for next time. An interesting variation of this scheme is to have two or more subroutines in a ring so that they are called in round robin order. On early hobbyist computers, tricks like this were commonly used in the horizontal refresh interrupt to reprogram the scan line address to repeat each scan line 4 times for the video controller. Computed subroutine calls were no problem because all CALL instructions were indexed (some processors only had CALL immediate).

DMA; Clock cycles

The built-in DMA controller is typically used to load or view program memory, depending on the state of the write enable signal, after the processor has been reset but still being held in a special wait state. Direct memory access (DMA) is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit. ...

Clock cycle efficiency is poor in comparison to most other similar processors. Eight clock cycles makes up one machine cycle. Most instructions take two machine cycles to execute. In synchronous digital electronics, such as most computers, a clock signal is a signal used to coordinate the actions of two or more circuits. ...

Support chips

In early microcomputers the companion CDP1861 graphics Video Display Controller chip (1861 for the NTSC video format, 1864 variant for PAL) used the built-in DMA controller to display bitmapped graphics. This chip could display 64 pixels horizontally and 128 pixels vertically, though by reloading the R0 register, the resolution could be reduced to 64×64 or 64×32 to use less memory or to make square pixels. Since the frame buffer was similar in size to the memory size, it was not unusual to display your program/data on the screen allowing you to watch the computer "think" (i.e. process its data). Programs which ran amok and accidentally overwrote themselves could be spectacular. Although the faster version of 1802 could operate at 5 MHz (at 5 V; it was faster at 10 V), it was usually operated at 3.58 MHz/2 to suit the requirements of the 1861 chip which gave a speed of a little over 100,000 instructions per second. 2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models (such as 2D geometric models, text, and digital images) and by techniques specific to them. ... A Video Display Controller or VDC is an integrated circuit which is the main component in a video signal generator, a device responsible for the production of a TV video signal in a computing or game system. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... For other uses, see PAL (disambiguation). ... For the use of the term raster in radio regulation, see frequency raster. ... This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen. ...

External links

• CDP1802 datasheet (PDF)
• COSMAC ELF website
• Spare Time Gizmos ELF 2K page
• Elf/1802 Emulation
• A Short Course in Programming (1980 text on RCA 1802 assembler)
• Early homebrew handheld computer using RCA 1802 and Forth

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