ASS #1

Eric Wei (ewei@physics.ubc.ca) Sun, 30 Jan 2000 02:41:52 -0800 

From: "Eric Wei" <ewei@physics.ubc.ca>
Subject: ASS #1
Date: Sun, 30 Jan 2000 02:41:52 -0800




Nice to know someone is having a headache over this =)

I'll try my best to answer some of your question.

> Why is the button 10-bits when the numbers 0 to 9 only need 4-bits?
We are assuming that it's a keypad with 10 buttons each linked to a pin on the Altera chip.
We can, however, build a decoder that decodes the input into a 4 bit representation but I think there is more hassle doing it that way.  I rather work with the 10 bit input.

> Also, the last test case says two buttons are pushed at exactly the same
> time. What kind of input will this create. Can you give an example? ie.
> input 5 = "0000000101"  and 6 = "0000000110" at the same time gives what
> for the 10-bit button?

Say for my last number, I pushed 7 and 4 at the same time.  The output I'll get is "0010010000".  Each bit that is "high" represents the paticular being pushed.  In my example, I am assuming that the MSB is 9 and LSB is 0.  Or "9876543210" corresponds to each bit in the 10-bit vector.

> How do you tell when the a number is entered? The button is a 10-bit
> vector that represents the number but how do you tell when it is entered
> if entry doesn't happen once per clock cycle. Shouldn't there be a input
> signal bit equivalent to the 224H port in the second lab? How do you
> tell the difference between entering 2 equal numbers, one after the
> other, without this?

say, when 9 is entered, you'll get "1000000000" (assuming 9 is the MSB in the bit vector).  When 5 is entered, you'll get "0000100000".

As for clocking, I am just as confused as you are... can't say much about it.


----- Original Message ----- 
From: "Shawn O'Neill" <Shawn_ONeill@telus.net>
To: <eece379@casas2.ece.ubc.ca>
Sent: Sunday, January 30, 2000 2:41 AM
Subject: Ass#1