CSC270 Homework 9 2012

--D. Thiebaut 15:31, 11 April 2012 (EDT)

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This assignment is due on 4/18/12, at the beginning of the lab.

Problem #1

Write the driver for the hardware shown below, that consists of a 1-bit port attached to a red LED. The driver should be a collection of 2 functions, one to turn the LED ON, and another function to turn the LED OFF.

Note that who ever designed this circuit didn't use the same approach you took in the lab. In particular this design is more expensive in terms of gates. Also, make sure you notice that the port is connected to D1 of the Data Bus, and not D0 as you did in the lab...

Problem #2

Same question with the hardware shown below. Y1' from the 7442 is connected to the CLR' input of the 7474. Y3' of the 7442 is connected to the PR' input of the 7474. Both the D and clock inputs of the 7474 are grounded.

Write the driver (2 functions) that can be used to turn the LED either ON, or OFF.

Problem #3

We want to connect some new hardware to the 6811, that we'll control via software. The hardware interface should activate an LED that will either blink at 500 KHz, or not blink at all, in which case it will stay OFF.

You need to propose a design that combines both hardware and software.

Your hardware design will be provided in the form of a schematic diagram.

The software design should be just two functions, one to activate the 500 KHz oscillation. The other turn the oscillation OFF. For example, here is a simple program that uses the two functions you have to write. The documentation explains what is going on.

	org	0000
start:  jsr	oscillate	;make hardware start 500KHz oscillation                           
        jsr	C027		;make oscillations last 1 second                                  
        jsr	turnLEDOff	;stop oscillations                                                
        jsr	C027		;LED stays off for 2 seconds                                      
        jsr	C027	
        jmp	start