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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 basic 8080 instruction cycle time was 1.95 μs, which was four clock cycles.) The SDK-80 allowed interface to an existing application or custom interface development. A monitor ROM was provided. RAM 256 bytes expandable to 1 KB; ROM 2 KB expandable to 4 KB; Size/weight 12 (W) × 0.5 (D) × 6.75 (H) inch
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.
In contrast, in direct memory access (DMA) operations, the CPU is uninvolved in the data transfer. The term can refer to either memory-mapped I/O (MMIO) or port-mapped I/O (PMIO). PMIO refers to transfers using a special address space outside of normal memory, usually accessed with dedicated instructions, such as IN and OUT in x86 architectures.
Mitsubishi Electric, Toshiba and NEC introduced 16 Mb DRAM memory chips manufactured with a 600 nm process in 1989. [47] NEC's 16 Mb EPROM memory chip in 1990. [47] Mitsubishi's 16 Mb flash memory chip in 1991. [47] Intel 80486DX4 CPU launched in 1994. IBM/Motorola PowerPC 601, the first PowerPC chip, was produced in 0.6 μm.
As the Execution Unit is executing the current instruction, the bus interface unit reads up to six (or four) bytes of opcodes in advance from the memory. The queue lengths were chosen based on simulation studies. [9] An exception is encountered when the execution unit encounters a branch instruction i.e. either a jump or a call instruction. In ...
Interface name Year introduced Connector Max transfer Main use Notes CAMAC: 1972: Processor independent: Industry use. S-100: 1974: 2×50 2.54 mm card edge: Designed around Intel 8080 but used with other processors too: Homebrew and industry use. VME: 1981: DIN 41612: 10 MByte/s: Motorola 68000 based: Industry use. STEbus: 1983: DIN 41612 a+c ...
Special function registers are in the upper area of addressable memory, from address 0x80 to 0xFF. This area of memory cannot be used for data or program storage, but is instead a series of memory-mapped ports and registers. All port input and output can therefore be performed by memory move operations on specified addresses in the SFR region.