ELET2100 - MICROPROCESSORS I

COURSE TEST #2 - WEDNESDAY 28th NOVEMBER 2007

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

( 1 ) Sketch the waveform for the ASCII <CR> character (0DH) for serial

transmission using 8-bit data, odd parity, one stop bit, 5600 baud.

Indicate the bit time on your sketch. [3]

( 2 ) Determine the instruction of the 8085 CPU that will cause the decoder in

Figure 1 (below) to turn ON the LED. [3]

( 3 ) Use any ports on the SDK-85 kit you used in the lab to control a 4-channel,

8-bit A/D converter. Explain the control signals used on the A/D IC. [3]

( 4 ) Using your design from Question ( 3 ) above, write AL code to read the four

channels and store them in memory starting at location 2090H. [5]

( 5 ) The 8155 IC contains a 14-bit Timer which is fed by a 1 MHz oscillator. You

however, wish to obtain a repetitive single pulse, every 400 µs from the

Timer Out pin. Explain how you can accomplish this task and show AL code

that will load the Timer (mode 3). [5]

( 6 ) (a) What are the two types of volatile memory ? [1]

(b) What is the abbreviation SIMM mean ? [1]

(c) The 8755 IC on the SDK-85 contains 2K of EPROM. What does the

abbreviation EPROM mean ? [1]

(d) Is “Flash” memory volatile or non-volatile ? [1]

( 7 ) Explain how the instructions SIM and RIM operate for serial

communications on the 8085 CPU. [4]

(8) Sketch a timing diagram for the instruction IN 22H, showing the control pins,

affected, the upper-half of the address bus and the data bus. [3]

Bonus mark:

How old (± 1-year) is Ramon Sargeant, your Lecturer from last week ?

Maximum mark = 30