How Do You Program and Design for the MC68000 Microprocessor?

[lightgreen]

One of my major subjects in this semester is Microprocessor, MC68000. I have a hard time with this subject. Please help me to answer certain questions:

1）Design address decoder for following devices
- RAM(128Kbyte) with initial address of $400000
-ROM(32kbyte) with initial address of $000000
-I/O with address between $800000-$80001F

2) Write a program which satisfies the equation: y= x(square) + z
y is a 16bit unsigned number which store in $1000
x and z is a 8 bit unsigned number which store in $1002-$1003

 

[jim mcnamara]

Do you know the instruction set for the Motorola chip? You need to know that already.

What work have you done so far? Please you show us.

 

[lightgreen]

The questios listed all are the theoretical question. We do not have to design the real circuit. For the first question, I already have the answers. But pls help me for the 2nd question.

 

[verafloyd]

For the square part use a look-up table and an index to count up to x and read the table (which should contain the square of each x values). The rest is straightforward; addition.

 

[rbj]

For the square part use a look-up table and an index to count up to x and read the table (which should contain the square of each x values). The rest is straightforward; addition.

the 68K has a multiply instruction. both signed and unsigned. squaring a number is trivial.

 

[lightgreen]

Sorry to say that I don understand at all what's going on at the moment. I'm thinking of using multiplication before, but the requirements for it really make me confuse. Besides that, if squaring a number is trivial, then can I assume that y=z? If not, what should I do? What are $1000, $1002,$1003? Is it a memory address at address register?

 

[verafloyd]

the 68K has a multiply instruction. both signed and unsigned. squaring a number is trivial.

You're right. But it -depending on the numbers- takes more clock cycles than doing it with a LUT.