0
In an 8085, the ALE pin pulses high for about one half clock cycle at the beginning of each machine cycle, approximately near the falling edge of CLK. At the falling edge of ALE, external hardware is expected to strobe the values of AD0-AD7 and hold them as the low order address values A0-A7. Other lines, such as IO/M-, S0, S1, and A8-A15 are also guaranteed valid at the falling edge of ALE, but they do not need to be strobed as they are not multiplexed. (All these lines do change during ALE, at about the 1/3 point depending on clock frequency, so they are considered invalid until the falling edge of ALE.) Following ALE, the AD0-AD7 bus lines become the data bus, D0-D7. This multiplexed scheme saves 8 pins on the chip design. In an 8085, the TRAP pin is a non maskable interrupt with highest priority. It must go high and stay high to be recognized, and it will not be recognized again until it goes low and then high. (Edge and level triggered.)The recognition point is on the falling edge of CLK, one clock cycle before the ALE that follows the last machine cycle of the instruction. When recognized, an internal RST instruction ocurrs, with a vector address of 0024H.
Wiki User
∙ 14y ago
Add your answer:
Earn +20 pts
What are the pins used to control interrupts?
The pins used to control interrupts in the 8085 are INTR/INTA, RST5.5, RST6.5, RST7.5, and TRAP.
Difference between 8080 and 8085?
The 8085 has a single +5V power supplyThe 8085 has a multiplexed low order address busThe 8085 has extra single pin interrupts, TRAP, RST7.5, RST6.5, and RST5.5The 8085 has serial I/O pins SID and SODThe 8085 has maskable interrupts and the RIM/SIM instructionThe 8085 includes the functionality of the 8224 clock genereator and 8228 system controllerThe 8085 added several 16 bit operations
Can you change the pins in 8085 microprocessor?
No. The pins are preset by Intel.
What is ALE in 8085 in microprocessor?
ALE=Address Latch Enabled.(pin number 30 in 8085)8085 has a special pin referred as ALE, which indicates whether multiplex bus functions as an address bus or a data bus. Whenever 8085 starts any new operation, ALE signal goes to logic 1 for about 1/2 clock cycle, at about the falling edge of CLK. If ALE=1 then multiplex bus functions as address bus. After that half clock cycle, it goes to logic 0 for nearly 3 or 4 clock cycles. If ALE=0 then multiplex bus acts as a data bus.The ALE pin helps to enable the latching of lower order ADDR bus. The AD0-AD7 pins, as well as other control pins such as S0, S1, IO/M-, and the other address pins A8-A15, are setup to be correct at the falling edge of ALE.
What is the meaning of the term 8085 in microprocessor8085?
The designation 8085 was given by Intel for an updated version of the 8080. The 8085 multiplexed the address bus, freeing up some pins, and Intel included newer functionality. The specific reason for the 5, in 8085, was to indicate that the 8085 operated on a single +5V power supply, unlike the 8080, which needed three power supplies, +5V, -5V, and +12V.
How many pins are present in 8085 and 8086 microprocessor?
There are 256 ports available in the 8085 microprocessor. The IN and OUT instructions have an 8-bit port number, and that is where the 256 comes from.In order to use ports, the hardware addressing system must decode IO/M-. Some implementations don't do this, so they map IO addresses to memory addresses. In that case, you could say there are 65536 possible IO addresses, but that is not the same as ports, because ports are specific to the IN and OUT instructions.The other "problem" with IN and OUT is that you cannot specify the address in a register, while you can do so with indirect memory addressing.
What is microprocesser 8085?
microprocessor 8085 is basic 8 bit microprocessor by Intel Corp. it has 64Kb memory and 16 address buses and 8 data buses it has 40 pin ic. 8 address and 8 data buses are multiplexed with each other for reducing the total number of pins from the microprocessor 8085 . it require 5MHz clock frequency for operation. only a crystal which connected easily across two pins of microprocessor can provide this clock.
Give over view of 8085 microprocessor?
The 8085 is an eight bit computer running on a 16 bit address bus. It has eight registers, A, B, C, D, E, H, L, and FLAGS, along with a 16 bit PC (Program Counter) and SP (Stack Pointer). Most intructions deal with eight bit values, but some deal with 16 bit values, and some registers can be paired to hold 16 bit values, such as BC, DE, and HL. The 8085 has multiple interrupt lines, INTR, RST5.5, RST6.5, RST7.5 and TRAP, and it can address 256 bytes of IO space. It has serial input (SID) and serial output (SOD) pins, but there is no implicit UART functionality built in. The 8085 has a READY pin which can be used to interface to slow memory, and a HOLD/HLDA set of pins that can be used to allow other bus masters to take over, such as in DMA operations.
What is the importance of INTA in 8085 microprocessor?
The INTA- pin on the 8085 is a read strobe that is used in response to the INTR sequence. It has the same timing as RD-, and external hardware is expected to provide an instruction opcode and, if necessary, the extra bytes, in response to INTA-.One of the enhancements made in the 8085 over the 8085 is the RST type instructions, which are single byte calls to specific locations in low memory. External hardware can be simplified by providing the RST opcode, without needing to provide a full CALL instruction.Not asked, but answered for completeness - the other four interrupt pins, RST5.5, RST6.5, RST7.5, and TRAP are 8085 enhancements that allow the use of automatic interrupt vectoring without using the INTA- pin.
HOW 8088 has segment arrangement in its two modes?
The two modes of the 8086/8088, minimum mode and maximum mode, have nothing to do with segment arrangement. The modes determine which pins on the chip have which functions. In minimum mode, certain pins are sacrificed in favor of a smaller implementation. In maximum mode, those pins take on other functions, and the original functions are generated by the Bus Controller chip.
What is a PINS petition in New York state?
PINS stands for Person In Need of Supervision
How is demultiplexing done in 8085 microprocessor?
it is nothing
