Friday, August 14, 2009

microcontroller 8085

16-bit operations
Although the 8085 was generally an 8-bit processor, it also had limited abilities to perform 16-bit operations: Any of the three 16-bit register pairs (BC, DE, HL) or SP could be loaded with an immediate 16-bit value (using LXI), incremented or decremented (using INX and DCX), or added to HL (using DAD). The XCHG operation exchanged the values of HL and DE. By adding HL to itself, it was possible to achieve the same result as a 16-bit arithmetical left shift with one instruction. The only 16 bit instructions that affect any flag is DAD, which sets the CY (carry) flag in order to allow for programmed 24-bit or 32-bit arithmetics (or larger), needed to implement floating point arithmetics, for instance.
[edit] Input/output scheme
The 8085 supported up to 256 input/output (I/O) ports, accessed via dedicated I/O instructions—taking port addresses as operands. This I/O mapping scheme was regarded as an advantage, as it freed up the processor's limited address space. Many CPU architectures instead use a common address space without the need for dedicated I/O instructions, although a drawback in such designs may be that special hardware must be used to insert wait states as peripherals are often slower than memory. However, in some simple 8080 computers, I/O was indeed addressed as if they were memory cells, "memory mapped", leaving the I/O commands unused. I/O addressing could also sometimes employ the fact that the processor would output the same 8-bit port address to both the lower and the higher address byte (i.e. IN 05h would put the address 0505h on the 16-bit address bus). Similar I/O-port schemes were used in the 8080-compatible Zilog Z80 as well as the closely related x86 families of microprocessors.
Development system
Intel produced a series of development systems for the 8080 and 8085, known as the Personal Development System. The original PDS was a large box (in the Intel corporate blue colour) which included a CPU and monitor, and used 8 inch floppy disks. It ran the ISIS operating system and could also operate an emulator pod and EPROM programmer. The later iPDS was a much more portable unit featuring a small green screen and a 5¼ inch floppy disk drive, and ran the ISIS-II operating system. It could also accept a second 8085 processor, allowing a limited form of multi-processor operation where both CPUs shared the screen, keyboard and floppy disk drive. In addition to an 8080/8085 assembler, Intel produced a number of compilers including PL/M-80and Pascal languages, and a set of tools for linking and statically locating programs to enable them to be burnt into EPROMs and used in embedded systems. The hardware support changes were announced and supported, but the software upgrades were not supported by the assembler, user manual or any other means. At times it was claimed they were not tested when that was false
For the extensive use of 8085 in various applications, the microprocessor is provided with an instruction set which consists of various instructions such as MOV, ADD, SUB, JMP etc. These instructions are written in the form of a program which is used to perform various operations such as branching, addition, subtraction, bitwise logical and bit shift operations. More complex operations and other arithmetic operations must be implemented in software. For example, multiplication is implemented using a multiplication algorithm
The 8085 processor has found marginal use in small scale computers up to the 21st century. The TRS-80 Model 100 line uses a 80C85. The CMOS version 80C85 of the NMOS/HMOS 8085 processor has/had several manufacturers, and some versions (eg. Tundra Semiconductor Corporation's CA80C85B) have additional functionality, eg. extra machine code instructions. One niche application for the rad-hard version of the 8085 has been in on-board instrument data processors for several NASA and ESA space physics missions in the 1990s and early 2000s, including CRRES, Polar, FAST, Cluster, HESSI, Sojourner (rover)[2], and THEMIS. The Swiss company SAIA used the 8085 and the 8085-2 as the CPUs of their PCA1 line of programmable logic controllers during the 1980s.
See also: Comparison of embedded computer systems on board the Mars rovers
MCS-85 Family
The 8085 CPU was only one part of a much larger family of chips developed by Intel, for building a complete system. Although the 8085 CPU itself was not a great success, many of these support chips (or their descendents) later found their use in combination with the 8086 microprocessor, and are still in use today, although not as the chips themselves, but with their equivalent functionality embedded into larger VLSI chips, namely the "Southbridge" chips of modern PCs.
8007-Ram controller
8155-RAM+ 3 I/O Ports+Timer
8156-RAM+ 3 I/O Ports+Timer
8202-Dynamic RAM Controller
8203-Dynamic RAM Controller
8205-1 Of 8 Binary Decoder
8206-Error Detection & Correction Unit
8207-DRAM Controller
8210-TTL To MOS Shifter & High Voltage Clock Driver
8212-8 Bit I/O Port
8216-4 Bit Parallel Bidirectional Bus Driver
8218/8219-Bus Controller
8222-Dynamic RAM Refresh Controller
8226-4 Bit Parallel Bidirectional Bus Driver
8231-Arithmetic Processing Unit
8232-Floating Point Processor
8237-DMA Controller
8251-Communication Controller
8253-Programmable Interval Timer
8254-Programmable Interval Timer
8255-Programmable Peripheral Interface
8256-Multifunction Support Controller
8257-DMA Controller
8259-Programmable Interrupt Controller
8271-Programmable Floppy Disk Controller
8272-Single/Double Density Floppy Disk Controller
8273-Programmable HDLC/SDLC Protocol Controller
8274-Multi-Protocol Serial Controller
8275-CRT Controller
8276-Small System CRT Controller
8278-Programmable KeyBoard Interface
8279-KeyBoard/Display Controller
8282-8-bit Non-Inverting Latch with Output Buffer
8283-8-bit Inverting Latch with Output Buffer
8291-GPIB Talker/Listener
8292-GPIB Controller
8293-GPIB Transceiver
8294-Data Encryption/Decryption Unit+1 O/P Port
8295-Dot Matrix Printer Controller
8296-GPIB Transceiver
8297-GPIB Transceiver
8355-16,384-bit (2048 x 8) ROM with I/O
8604-4096-bit (512 x 8) PROM
8702-2K-bit (265 x 8 ) PROM
8755-EPROM+2 I/O Ports
Educational Use
In many engineering schools in Iraq, Syria, Turkey, Bangladesh, Iran, India, Pakistan, Brazil, Macedonia, Mexico, Germany, Greece, Hungary, Panama, Nepal, Malaysia and Bosnia and Herzegovina[2] the 8085 processor is popularly used in many introductory microprocessor courses.
8085 simulators exist aplenty for educational use. Freely available open source variants include GNUSim8085 and GSim85[3] working on both, GNU/Linux and Windows, a freely available web based simulator (including assembler) can be found here. Closed source freeware simulators for the Microsoft Win32 platform include Win85 [4] (which also emulates undocumented operations of the chip) and Sim8085.

1 comment:

  1. Nice posting,thanks for sharing the nice information and ideas.I read the full article of the microprocessor and this article provide the nice information.I have to sure bookmark this blog.

    electronic board design