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The Intel 8085 ("eighty-eighty-five") is an 8-bit microprocessor produced by Intel and introduced in March 1976. [2] It is the last 8-bit microprocessor developed by Intel. It is software-binary compatible with the more-famous Intel 8080 with only two minor instructions added to support its added interrupt and serial input/output features.
The 8255 is a member of the MCS-85 family of chips, designed by Intel for use with their 8085 and 8086 microprocessors and their descendants. [1] It was first available in a 40-pin DIP and later a 44-pin PLCC packages. [2] It found wide applicability in digital processing systems and was later cloned by other manufacturers.
The 8259 may be configured to work with an 8080/8085 or an 8086/8088. On the 8086/8088, the interrupt controller will provide an interrupt number on the data bus when an interrupt occurs. The interrupt cycle of the 8080/8085 will issue three bytes on the data bus (corresponding to a CALL instruction in the 8080/8085 instruction set).
One example of this is the NMOS 8255 PIO design, originally intended as an 8085 peripheral chip, that has been used in Z80 and x86 embedded systems and many other contexts for several decades. Modern low power versions are available as CMOS or BiCMOS implementations, similar to the 7400-series.
Operation mode of the PIT is changed by setting the above hardware signals. For example, to write to the Control Word Register, one needs to set CS =0, RD =1, WR =0, A1=A0=1. The control word register contains the programmed information which will be sent (by the microprocessor) to the device. It defines how each channel of the PIT logically works.
Memory-mapped I/O is preferred in IA-32 and x86-64 based architectures because the instructions that perform port-based I/O are limited to one register: EAX, AX, and AL are the only registers that data can be moved into or out of, and either a byte-sized immediate value in the instruction or a value in register DX determines which port is the source or destination port of the transfer.
6- and 10-pin ISP header diagrams The in-system programming (ISP) programming method is functionally performed through SPI , plus some twiddling of the Reset line. As long as the SPI pins of the AVR are not connected to anything disruptive, the AVR chip can stay soldered on a PCB while reprogramming.
Open collector, open drain, open emitter, and open source refer to integrated circuit (IC) output pin configurations that process the IC's internal function through a transistor with an exposed terminal that is internally unconnected (i.e. "open").