Question

Consider a memory system with a 14 bit long address. Produce the answer to each of the following parts using hexadecimal numbers.

a. There is a 1.5k byte RAM device, starting at address $200. What is its last address?

b. There is a 1k byte EPROM device, starting at address $900.What is is last address?

c. There is a 7k byte ROM device, its last address is at the highest system address. What is its first address?

d. Use your answers from the earlier parts to draw one memory map. Be sure to indicate the first and last address of each region where a device appears in the memory map

Answer 1

a)

1.5k bytes

means 1.5*1024 bytes = 1536 bytes.

Now in hexadecimal it will be 600.

Since the start address is $200 and the size of the memory is 600 the last address will be 7FF.

b)

1k byte means size in hexadecimal is 400.

Since the first address is 900 The last address will be 900+400 = CFF

c)

Since the size of the memory is 7k that means that in hexadecimal it will be 1C00.

Since it is 14 bit address line hte last address will be 3FFF. only 14 bits can be accomodated.

So the starting address will be 3FFF-1C00 + 1= 2400

d)

The memory map is simple and we know how the 3 memory are there in the memory map. We can use the above to tell the locations.