ELET2100 (EL21C) - MICROPROCESSORS I

COURSE TEST #2 – WEDNESDAY 22nd NOVEMBER 2006

Time: (3:00 - 4:00 )PM

( 1 ) Which control signals are activated when the OUT instruction is executed ? [2]

( 2 ) Use these signal, and any other signals from the address & data bus, to turn ON

an LED using the instruction OUT 45H (show logic gates used). [4]

( 3 ) An 8-bit A/D converter gives full-scale for an analog input voltage of 2.00V.

What is the resolution of the device ? [2]

( 4 ) The EOC pin of the A/D converter is connected to the RST5.5 pin on an SDK-85 kit

in the lab. The OE pin is interfaced to Bit 0 of Port 21H and the A/D data

pins are interfaced to Port 22H.

Write code to read the A/D data into memory location 20A0H. [4]

( 5 ) If the output of the A/D converter is 8FH. What is the analog input voltage ? [2]

( 6 ) Sketch the waveform for the following serial transmission using 8-bit data, even

parity, one stop bit, 9600 baud: ASCII character (75H). [4]

( 7 ) How long does it take to transmit the total frame ? [2]

( 8 ) How many characters can be transmitted in 1 second ? [2]

( 9 ) Show the contents of the Stack, the SP-register, and the A-register, after the

following code is executed:

LXI SP, 3000H

MVI A, 24H

MOV C, A

MVI B, 12H

PUSH B

HLT [4]

( 10 ) The subroutine DLAY, which you use in the lab, is shown below.

Determine exactly the time this routine takes if it is entered with DE=0032h.

What registers are destroyed ? (Assume 8085 clock crystal = 3 MHz) [3+1]

DLAY: DCX D [ 6 states ]

MOV A, D [ 4 states ]

ORA E [ 4 states ]

JNZ DLAY [7/10 states]

RET [10 states ]

Bonus mark:

What is the Date of the final exam for this course ?

[ Maximum mark = 30 ]

NB: Add marks for Class Test #1 & 2 (total out of 60). Divide by 3 to convert to 20% of Final.

Please hand-in all Lab Reports by end of Week 13.

Coursework (20%) and Lab (20%) marks will be posted on Notice Board outside my Office

on/after Monday 4^th December 2006. Please report errors as soon as possible !!!