01․ In a vector interrupt
TRAP, RST 7.5, RST 6.5 and RST 6.5 are the vector interrupts in 8085. In a vector interrupt the branch address is assigned to a specific location in memory page without any external hardware.
02․ A sequence of two registers that multiplies the content of DE register pair by two and stores the result in HL register pair (in 8085 assembly language) is
XCHG → exchange the content of DE register pair with HL pair. DAD H → add the content of HL pair with HL pair. So, after following these two sequences of instructions the content of DE register pair will be multiplied by two and saved to the HL register pair.
03․ Identify the programmable interval timer from the following
8253 and 8254 are the programmable interval timer. It can generate accurate time delays by using software instruction.It can be used as accurate time delays,square wave generator etc.
04․ Identify the communication interfacing device from the following
Programmable communication interface is used for the serial data transmission.Intel 8251 is a programmable communication interface.It is Universal Synchronous /Asynchronous Receiver/ Transmitter (USART).
05․ Identify the programmable DMA controller from the following
In DMA data transfer data is directly transferred between I/O to the RAM or from the RAM to the I/O. 8257 and the 8237 are used as a programmable DMA controller. In this question the correct answer would be 8257.
06․ Pick up the programmable interrupt controller from the following
8259 is a programmable interrupt controller which is designed to work with microprocessor like 8085,8086 and 8088.It can manage eight interrupts according to the instruction written into its control registers.
07․ Identify the non-programmable interfacing device from the following
8212 has a non-programmable 8-Bit I/O Port.
08․ The maximum number of seven segment displays that can be connected to 8279 is
The maximum number of seven segment displays that can be connected to 8279 is 18.
09․ Using one 8259 IC is equivalent to providing …………. INTR pins on 8085
8259 is a programmable interrupt controller designed to work with microprocessor like 8085,8086 and 8088. It can manage eight interrupts according to the instructions written to its control registers.This is equivalent to providing eight interrupt pins in place of one INTR pin in 8085 microprocessor.
10․ Total number of modes the 8253 can work
The 8253 is a 24 pin IC which can be programmed in any of the following 6 operating modes e.g. Interrupt on terminal count,programmable one shot,Rate generator, Square wave generator, software triggered strobe and hardware triggered strobe.