The Intel 8085 ("''eighty-eighty-five''") is an
8-bit
In computer architecture, 8-bit Integer (computer science), integers or other Data (computing), data units are those that are 8 bits wide (1 octet (computing), octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) arc ...
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
produced by
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
and introduced in March 1976. It is software-
binary compatible
Binary-code compatibility (binary compatible or object-code-compatible) is a property of a computer system, meaning that it can run the same executable code, typically machine code for a general-purpose computer CPU, that another computer syst ...
with the more-famous
Intel 8080
The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
with only two minor instructions added to support its added interrupt and serial input/output features. However, it requires less support circuitry, allowing simpler and less expensive
microcomputer
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PC ...
systems to be built.
The "5" in the part number highlighted the fact that the 8085 uses a single +5-
volt
The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827).
Defi ...
(V) power supply by using
depletion-mode transistors, rather than requiring the +5 V, −5 V and +12 V supplies needed by the 8080. This capability matched that of the competing
Z80
The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were ...
, a popular 8080-derived CPU introduced the year before. These processors could be used in computers running the
CP/M operating system
CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
.
The 8085 is supplied in a 40-pin
DIP package. To maximise the functions on the available pins, the 8085 uses a multiplexed address/data (AD
0-AD
7) bus. However, an 8085 circuit requires an 8-bit address latch, so Intel manufactured several support chips with an address latch built in. These include the 8755, with an address latch, 2 KB of EPROM and 16 I/O pins, and the 8155 with 256 bytes of RAM, 22 I/O pins and a 14-bit programmable timer/counter. The multiplexed address/data bus reduced the number of PCB tracks between the 8085 and such memory and I/O chips.
Both the 8080 and the 8085 were eclipsed by the
Zilog Z80
The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples wer ...
for desktop computers, which took over most of the
CP/M
CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
computer market, as well as a share of the booming
home-computer market in the early-to-mid-1980s.
The 8085 had a long life as a controller, no doubt thanks to its built-in serial I/O and five prioritized interrupts, arguably microcontroller-like features that the Z80 CPU did not have. Once designed into such products as the
DECtape II controller and the
VT102
The VT100 is a video terminal, introduced in August 1978 by Digital Equipment Corporation (DEC). It was one of the first terminals to support ANSI escape codes for cursor control and other tasks, and added a number of extended codes for special f ...
video terminal in the late 1970s, the 8085 served for new production throughout the lifetime of those products. This was typically longer than the product life of desktop computers.
Description
![Anschlussbelegung 8085](https://upload.wikimedia.org/wikipedia/commons/a/ab/Anschlussbelegung_8085.gif)
The 8085 is a conventional
von Neumann Von Neumann may refer to:
* John von Neumann (1903–1957), a Hungarian American mathematician
* Von Neumann family
* Von Neumann (surname), a German surname
* Von Neumann (crater), a lunar impact crater
See also
* Von Neumann algebra
* Von Ne ...
design based on the Intel 8080. Unlike the 8080 it does not multiplex state signals onto the data bus, but the 8-bit
data bus
In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This ex ...
is instead multiplexed with the lower eight bits of the 16-bit
address bus
In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This ex ...
to limit the number of pins to 40. State signals are provided by dedicated bus control signal pins and two dedicated bus state ID pins named S0 and S1. Pin 40 is used for the power supply (+5 V) and pin 20 for ground. Pin 39 is used as the Hold pin. The processor was designed using
nMOS circuitry, and the later "H" versions were implemented in Intel's enhanced nMOS process called
HMOS II ("High-performance MOS"), originally developed for fast static RAM products. Only a single 5-volt power supply is needed, like competing processors and unlike the 8080. The 8085 uses approximately 6,500
transistor
upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink).
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...
s.
The 8085 incorporates the functions of the 8224 (clock generator) and the 8228 (system controller) on chip, increasing the level of integration. A downside compared to similar contemporary designs (such as the Z80) is the fact that the buses require demultiplexing; however, address latches in the Intel 8155, 8355, and 8755 memory chips allow a direct interface, so an 8085 along with these chips is almost a complete system.
The 8085 has extensions to support new interrupts, with three maskable vectored interrupts (RST 7.5, RST 6.5 and RST 5.5), one
non-maskable interrupt
In computing, a non-maskable interrupt (NMI) is a hardware interrupt that standard interrupt-masking techniques in the system cannot ignore. It typically occurs to signal attention for non-recoverable hardware errors. Some NMIs may be masked, but ...
(TRAP), and one externally serviced interrupt (INTR). Each of these five interrupts has a separate pin on the processor, a feature which permits simple systems to avoid the cost of a separate interrupt controller. The RST 7.5 interrupt is edge triggered (latched), while RST 5.5 and 6.5 are level-sensitive. All interrupts are enabled by the EI instruction and disabled by the DI instruction. In addition, the SIM (Set Interrupt Mask) and RIM (Read Interrupt Mask) instructions, the only instructions of the 8085 that are not from the 8080 design, allow each of the three maskable RST interrupts to be individually masked. All three are masked after a normal CPU reset. SIM and RIM also allow the global interrupt mask state and the three independent RST interrupt mask states to be read, the pending-interrupt states of those same three interrupts to be read, the RST 7.5 trigger-latch flip-flop to be reset (cancelling the pending interrupt without servicing it), and serial data to be sent and received via the SOD and SID pins, respectively, all under program control and independently of each other.
SIM and RIM each execute in four clock cycles (T states), making it possible to sample SID and/or toggle SOD considerably faster than it is possible to toggle or sample a signal via any I/O or memory-mapped port, e.g. one of the port of an 8155. (In this way, SID can be compared to the SO
Set Overflow"pin of the 6502 CPU contemporary to the 8085.)
Like the 8080, the 8085 can accommodate slower memories through externally generated
wait state
A wait state is a delay experienced by a computer processor when accessing external memory or another device that is slow to respond.
Computer microprocessors generally run much faster than the computer's other subsystems, which hold the data the ...
s (pin 35, READY), and has provisions for
Direct Memory Access
Direct memory access (DMA) is a feature of computer systems and allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU).
Without DMA, when the CPU is using programmed input/output, it is t ...
(DMA) using HOLD and HLDA signals (pins 39 and 38). An improvement over the 8080 is that the 8085 can itself drive a
piezoelectric crystal
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word ''p ...
directly connected to it, and a built-in clock generator generates the internal high-amplitude
two-phase clock
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits.
A clock sign ...
signals at half the crystal frequency (a 6.14 MHz crystal would yield a 3.07 MHz clock, for instance). The internal clock is available on an output pin, to drive peripheral devices or other CPUs in lock-step synchrony with the CPU from which the signal is output. The 8085 can also be clocked by an external oscillator (making it feasible to use the 8085 in synchronous multi-processor systems using a system-wide common clock for all CPUs, or to synchronize the CPU to an external time reference such as that from a video source or a high-precision time reference).
The 8085 is a
binary compatible
Binary-code compatibility (binary compatible or object-code-compatible) is a property of a computer system, meaning that it can run the same executable code, typically machine code for a general-purpose computer CPU, that another computer syst ...
follow-up on the 8080. It supports the complete
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 ' ...
of the 8080, with exactly the same instruction behavior, including all effects on the CPU flags (except for the AND/ANI operation, which sets the AC flag differently). This means that the vast majority of object code (any program image in ROM or RAM) that runs successfully on the 8080 can run directly on the 8085 without translation or modification. (Exceptions include timing-critical code and code that is sensitive to the aforementioned difference in the AC flag setting or differences in undocumented CPU behavior.) 8085 instruction timings differ slightly from the 8080—some 8-bit operations, including INR, DCR, and the heavily used MOV r,r' instruction, are one clock cycle faster, but instructions that involve 16-bit operations, including stack operations (which increment or decrement the 16-bit SP register) generally one cycle slower.
It is of course possible that the actual 8080 and/or 8085 differs from the published specifications, especially in subtle details. (The same is not true of the Z80.) As mentioned already, only the SIM and RIM instructions were new to the 8085.
[Note that the Z80 assigns different instructions—two of the Z80's 6 relative jumps—to the opcodes that the 8085 uses for RIM and SIM, making 8085 programs that use these instructions generally unable to run on the Z80 without modification. Since use of these instructions usually relates to 8085-specific hardware features, the necessary program modification would typically be nontrivial.]
Programming model
The processor has seven 8-bit
registers accessible to the programmer, named A, B, C, D, E, H, and L, where A is also known as the accumulator. The other six registers can be used as independent byte-registers or as three 16-bit register pairs, BC, DE, and HL (or B, D, H, as referred to in Intel documents), depending on the particular instruction. Some instructions use HL as a (limited) 16-bit accumulator. As in the 8080, the contents of the memory address pointed to by HL can be accessed as pseudo register M. It also has a 16-bit
program counter
The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, is ...
and a 16-bit
stack pointer
In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, program stack, control stack, run-time stack, or mach ...
to memory (replacing the 8008's internal
stack
Stack may refer to:
Places
* Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group
* Blue Stack Mountains, in Co. Donegal, Ireland
People
* Stack (surname) (including a list of people ...
). Instructions such as PUSH PSW, POP PSW affect the Program Status Word (accumulator and flags). The accumulator stores the results of arithmetic and logical operations, and the flags register bits (sign, zero, auxiliary carry, parity, and carry flags) are set or cleared according to the results of these operations. The sign flag is set if the result has a negative sign (i.e. it is set if bit 7 of the accumulator is set). The auxiliary or half carry flag is set if a carryover from bit 3 to bit 4 occurred. The parity flag is set to 1 if the parity (number of 1-bits) of the accumulator is even; if odd, it is cleared. The zero flag is set if the result of the operation was 0. Lastly, the carry flag is set if a carryover from bit 7 of the accumulator (the MSB) occurred.
Commands/instructions
As in many other 8-bit processors, all instructions are encoded in a single byte (including register-numbers, but excluding immediate data), for simplicity. Some of them are followed by one or two bytes of data, which can be an immediate operand, a memory address, or a port number. A NOP "no operation" instruction exists, but does not modify any of the registers or flags. Like larger processors, it has CALL and RET instructions for multi-level procedure calls and returns (which can be conditionally executed, like jumps) and instructions to save and restore any 16-bit register-pair on the machine stack. There are also eight one-byte call instructions (RST) for subroutines located at the fixed addresses 00h, 08h, 10h,...,38h. These are intended to be supplied by external hardware in order to invoke a corresponding interrupt-service routine, but are also often employed as fast system calls. One sophisticated instruction is XTHL, which is used for exchanging the register pair HL with the value stored at the address indicated by the stack pointer.
8-bit instructions
All two-operand 8-bit arithmetic and logical (ALU) operations work on the 8-bit
accumulator (the A register). For two-operand 8-bit operations, the other operand can be either an immediate value, another 8-bit register, or a memory cell addressed by the 16-bit register pair HL. The only 8-bit ALU operations that can have a destination other than the accumulator are the unary incrementation or decrementation instructions, which can operate on any 8-bit register or on memory addressed by HL, as for two-operand 8-bit operations. Direct copying is supported between any two 8-bit registers and between any 8-bit register and an HL-addressed memory cell, using the MOV instruction. An immediate value can also be moved into any of the foregoing destinations, using the MVI instruction. Due to the regular encoding of the MOV instruction (using nearly a quarter of the entire opcode space) there are redundant codes to copy a register into itself (''MOV B,B'', for instance), which are of little use, except for delays.
[Even so, there is no need for seven different effectively identical delay instructions, and they are also identical in effect and form to the NOP instruction, except that NOP conveniently has the opcode 00 hex.] However, what would have been a copy from the HL-addressed cell into itself (i.e., ''MOV M,M'') instead encodes the
HLT instruction, halting execution until an external reset or unmasked interrupt occurs.
[(The TRAP interrupt, being an NMI, can always bring the 8085 out of the HALT state.)]
16-bit operations
Although the 8085 is an 8-bit processor, it has some 16-bit operations. Any of the three 16-bit register pairs (BC, DE, HL or SP) can be loaded with an immediate 16-bit value (using LXI), incremented or decremented (using INX and DCX), or added to HL (using DAD). LHLD loads HL from directly addressed memory and SHLD stores HL likewise. The XCHG operation exchanges the values of HL and DE. Adding HL to itself performs a 16-bit arithmetical left shift with one instruction. The only 16-bit instruction that affects any flag is DAD (adding BC, DE, HL, or SP, to HL), which updates the carry flag to facilitate 24-bit or larger additions and left shifts. Adding the stack pointer to HL is useful for indexing variables in (recursive) stack frames. A stack frame can be allocated using DAD SP and SPHL, and a branch to a computed pointer can be done with PCHL. These abilities make it feasible to compile languages such as
PL/M
The PL/M programming language
(an acronym of ''Programming Language for Microcomputers'')
is a high-level language conceived and developed by
Gary Kildall in 1973 for Hank Smith at Intel for its microprocessors.
Overview
The language incorpor ...
,
Pascal
Pascal, Pascal's or PASCAL may refer to:
People and fictional characters
* Pascal (given name), including a list of people with the name
* Pascal (surname), including a list of people and fictional characters with the name
** Blaise Pascal, Fren ...
, or
C with 16-bit variables and produce 8085 machine code. Subtraction and bitwise logical operations on 16 bits is done in 8-bit steps. Operations that have to be implemented by program code (subroutine libraries) include comparisons of signed integers as well as multiplication and division.
Undocumented instructions
A number of undocumented instructions and flags were discovered by two software engineers, Wolfgang Dehnhardt and Villy M. Sorensen in the process of developing an 8085 assembler. These instructions use 16-bit operands and include indirect loading and storing of a word, a subtraction, a shift, a rotate, and offset operations.
Input/output scheme
The 8085 supports both
port-mapped and memory-mapped io. It supports up to 256
input/output
In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...
(I/O) ports via dedicated Input/Output instructions, with port addresses as operands. Port-mapped IO can be an advantage on processors with limited address space. During a port-mapped I/O bus cycle, the 8-bit I/O address is output by the CPU on both the lower and upper halves of the 16-bit address bus.
Devices designed for memory mapped I/O can also be accessed by using the LDA (load accumulator from a 16-bit address) and STA (store accumulator at a 16-bit address specified) instructions, or any other instructions that have memory operands. A memory-mapped IO transfer cycle appears on the bus as a normal memory access cycle.
Development system
Intel produced a series of development systems for the 8080 and 8085, known as the MDS-80 Microprocessor System. The original development system had an 8080 processor. Later 8085 and 8086 support was added including ICE (
in-circuit emulators). It is a large and heavy desktop box, about a 20" cube (in the Intel corporate blue color) which includes a CPU, monitor, and a single 8-inch floppy disk drive. Later an external box was made available with two more floppy drives. It runs the
ISIS
Isis (; ''Ēse''; ; Meroitic: ''Wos'' 'a''or ''Wusa''; Phoenician: 𐤀𐤎, romanized: ʾs) was a major goddess in ancient Egyptian religion whose worship spread throughout the Greco-Roman world. Isis was first mentioned in the Old Kingd ...
operating system and can also operate an
emulator
In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run so ...
pod and an external
EPROM
An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power s ...
programmer. This unit uses the Multibus card cage which was intended just for the development system. A surprising number of spare card cages and processors were being sold, leading to the development of the Multibus as a separate product.
The later iPDS is a portable unit, about 8"16"20", with a handle. It has a small green screen, a keyboard built into the top, a 5¼ inch floppy disk drive, and runs the ISIS-II operating system. It can also accept a second 8085 processor, allowing a limited form of multi-processor operation where both processors run simultaneously and independently. The screen and keyboard can be switched between them, allowing programs to be assembled on one processor (large programs took awhile) while files are edited in the other. It has a
bubble memory
Bubble memory is a type of non-volatile computer memory that uses a thin film of a magnetic material to hold small magnetized areas, known as ''bubbles'' or ''domains'', each storing one bit of data. The material is arranged to form a series o ...
option and various programming modules, including EPROM, and
Intel 8048
The MCS-48 microcontroller series, Intel's first microcontroller, was originally released in 1976. Its first members were 8048, 8035 and 8748. The 8048 is probably the most prominent member of the family. Initially, this family was produced u ...
and
8051 programming modules which are plugged into the side, replacing stand-alone device programmers. In addition to an 8080/8085 assembler, Intel produced a number of compilers including those for
PL/M-80 and
Pascal
Pascal, Pascal's or PASCAL may refer to:
People and fictional characters
* Pascal (given name), including a list of people with the name
* Pascal (surname), including a list of people and fictional characters with the name
** Blaise Pascal, Fren ...
, and a set of tools for linking and statically locating programs to enable them to be burned into
EPROM
An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power s ...
s and used in
embedded system
An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' as ...
s.
A lower cost "MCS-85 System Design Kit" (SDK-85) board contains an 8085 CPU, an 8355 ROM containing a debugging monitor program, an 8155 RAM and 22 I/O ports, an 8279 hex keypad and 8-digit 7-segment LED, and a TTY (Teletype) current loop serial interface. Pads are available for one more 2K×8 8755 EPROM, and another RAM 8155 I/O Timer/Counter can be optionally added. All data, control, and address signals are available on dual pin headers, and a large prototyping area is provided.
List of Intel 8085
Applications
The 8085 processor was used in a few early personal computers, for example, the
TRS-80 Model 100 line
The TRS-80 Model 100 is a portable computer introduced in April 26th, 1983. It is one of the first notebook-style computers, featuring a keyboard and liquid crystal display, in a battery-powered package roughly the size and shape of a notepad o ...
used an OKI manufactured 80C85 (MSM80C85ARS). The
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFE ...
version 80C85 of the NMOS/HMOS 8085 processor has several manufacturers. In the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
, an 80C85 clone was developed under the
designation IM1821VM85A (russian:
ИМ1821ВМ85А, italic=yes) 2016 was still in production.
Some manufacturers provide variants with additional functions such as additional instructions.
The
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 ...
version of the 8085 has been in on-board instrument data processors for several
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 ...
and
ESA
, 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 ...
space physics missions in the 1990s and early 2000s, including
CRRES
The Combined Release and Radiation Effects Satellite (CRRES) was launched on July 25, 1990, into a geosynchronous transfer orbit (GTO) for a nominal three-year mission to investigate fields, plasmas, and energetic particles inside the Earth's ...
,
Polar
Polar may refer to:
Geography
Polar may refer to:
* Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates
* Polar climate, the c ...
,
FAST,
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 ...
,
HESSI, the
Sojourner
A sojourner is a person who resides temporarily in a place.
Sojourner may also refer to:
* Sojourner Truth (1797–1883), abolitionist and women's rights activist
* Albert Sojourner (1872–1951), member of the Mississippi House of Representative ...
Mars Rover, and
THEMIS
In Greek mythology and Ancient Greek religion, religion, Themis (; grc, Θέμις, Themis, justice, law, custom) is one of the twelve Titans, Titan children of Gaia and Uranus (mythology), Uranus, and the second wife of Zeus. She is the godde ...
. The Swiss company SAIA used the 8085 and the 8085-2 as the CPUs of their PCA1 line of
programmable logic controller
A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity tha ...
s during the 1980s.
Pro-Log Corp.put the 8085 and supporting hardware on an STD Bus format card containing CPU, RAM, sockets for ROM/EPROM, I/O and external bus interfaces. The included Instruction Set Reference Card uses entirely different mnemonics for the Intel 8085 CPU. The product was a direct competitor to Intel's
Multibus
Multibus is a computer bus standard used in industrial systems. It was developed by Intel Corporation and was adopted as the IEEE 796 bus.
The Multibus specification was important because it was a robust, well-thought out industry standard with ...
card offerings.
second source
In the electronics industry, a second source is a company that is licensed to manufacture and sell components originally designed by another company (the first source).
It is common for engineers and purchasers to avoid components that are only av ...
image:Soviet made processor KM1821VM85A.jpg, NZPP Novosibirsk IM1821VM85 (Soviet Union)
image:Ic-photo-OKI--M80C85A-2--(8085-CPU).JPG,
The 8085 CPU is one part of a family of chips developed by Intel for building a complete system. Many of these support chips were also used with other processors. The original IBM PC based on the Intel 8088 processor used several of these chips; the equivalent functions today are provided by
– 2K-bit static MOS RAM with 3 I/O Ports and Timer. The industrial version of ID8155 was available for in quantities of 100 and up.
The military version of M8155 was available for in quantities of 100. There is a version of Intel 8155-2.
technology which it uses 30 percent less power than the previous generation. The plastic package version of P8155H (3 MHz) and P8155H-2 (5 MHz) are available for and per 100 in quantities respectfully.
* 8156 – 2K-bit static MOS RAM with 3 I/O Ports and Timer. The industrial version of ID8156 was available for in quantities of 100.
There is a version of Intel 8156-2.
The available 8156H was introduced using the HMOS II technology which it uses 30 percent less power than the previous generation. The plastic package version of P8156H (3 MHz) and P8156H-2 (5 MHz) are available for and per 100 in quantities respectfully.
* 8185 – 1,024 x 8-bit Static RAM. The version of Intel 8185-2 was available for in quantity of 100.
* 8355 – 2,048 × 8-bit ROM, two 8-bit I/O ports. The industrial version of ID8355 was available for in quantities of 1000.
There is a version of Intel 8355-2.
* 8755 – 2048 x 8-bit EPROM, two 8-bit I/O ports. The Intel 8755A-2 is the version. That version was available for in quantity of 100.
There was an Industrial Grade version Intel I8755A-8.
* 8202 – Dynamic RAM Controller. This supports the Intel 2104A, 2117, or 2118 DRAM modules, up to 128 KB of DRAM modules. Price was reduced to for quantities of 100 for the D8202 package style around May 1979.
* 8203 – Dynamic RAM Controller. The Intel 82C03 CMOS version dissipates less than 25 mA. It supports up to 16x 64K-bit RAM for a total capacity of up to . It refreshes every 10 to 16 microseconds. It supports multiplexing of row and column memory addresses. It generates strobes to latch the address internally. It arbitrates between simultaneous requests for memory access and refresh. It also acknowledges memory-access cycles to the system CPU. The 82C03 was available in either ceramic or plastic packages for in 100 pieces quantity.
* 8207 – DRAM Controller
* 8206 – Error Detection & Correction Unit
* 8210 – TTL To MOS Shifter & High Voltage Clock Driver
* 8212 – 8-bit I/O Port. The industrial version of ID8212 was available for in quantities of 100.
* 8216 – 4-bit Parallel Bidirectional Bus Driver. The industrial version of ID8216 was available for in quantities of 100.
* 8218/8219 – Bus Controller
* 8226 – 4-bit Parallel Bidirectional Bus Driver. The industrial version of ID8226 was available for in quantities of 100.
* 8254 – Programmable Interval Timer. The 82C54 CMOS version was outsourced to
– Programmable Peripheral Interface
* 8256 – Multifunction Peripheral. This multifunction chip uses
s. The Intel 8256AH was available for in quantities of 100. This integrated circuit chip integrates the chips with the following functionality:
**
– Single/Double Density Floppy Disk Controller. It is compatible with
(MFM). This version was available for in quantities of 100.
Protocol Controller. This device supports ISO/
's HDLC and IBM's SDLC communication protocols. These were available for () and () in quantities of 100.
* 8274 – Multi-Protocol Serial Controller. This support three different protocols using the following feature of Asynchronous Operation, Byte Synchronous Operation and Bit Synchronous Operation. The Byte Synchronous mode is compatible to IBM's
signal protocol. The Bit Synchronous mode is compatible to IBM's
international standard as well. It was packaged in 40-pin product using the Intel's
technology. The available version is rated up to 880 kilobaud for in the quantities of 100. NEC µPD7201 was also compatible.
* 8275 – Programmable CRT Controller. It refreshes the raster scan display by buffering from main memory and keeping track of the display portion. This version was available for in quantities of 100.
* 8276 – Small System CRT Controller
* 8278 – Programmable Key Board Interface
*
Talker/Listener. This controller can operate from 1 to . It was available for in quantities of 100.
Controller. Designed around Intel 8041A which it has been programmed as an controller interface element. It also controls the bus using three lock-up timers to detect issues on the GPIB bus interface. It was available for in quantities of 100.
* 8293 – GPIB Transceiver. This chipset supports up to 4 different modes: Mode 0 Talker/Listener Control Lines, Mode 1 Talker/Listener/Controller Control Lines, Mode 2 Talker/Listener/Controller Data Lines, and Mode 3 Talker/Listener Data Lines. It was available for in quantities of 100. At the time of release, it was available in samples then full production in the first quarter of 1980.
* 8294 – Data Encryption/Decryption Unit + 1 O/P Port. It encrypts and decrypts 64-bit blocks of data using the
algorithm. This also uses the
encryption algorithm. This DEU operates using a 56-bit user-specified key to generate 64-bit cipher words. It was available for in quantities of 100.
* 8295 – Dot Matrix Printer Controller. This interfaces with LRC 7040 Series
and other small printers as well. It was available for in quantities of 100.
In many engineering schools the 8085 processor is used in introductory microprocessor courses. Trainer kits composed of a printed circuit board, 8085, and supporting hardware are offered by various companies. These kits usually include complete documentation allowing a student to go from soldering to assembly language programming in a single course. Also, the architecture and instruction set of the 8085 are easy for a student to understand. Shared Project versions of educational and hobby 8085-based
s are noted below in the External Links section of this article.
Software simulators are available for the 8085 microprocessor, which allow simulated execution of opcodes in a graphical environment.
.
;Books
*
*
*
* Bill Detwiler ''Tandy TRS-80 Model 100 Teardown'' Tech Republic, 2011 Web
* ; 495 pages
* ; 466 pages
* ; 303 pages
;Reference Cards
* ''Intel 8085 Reference Card''; Saundby; 2 pages.