Classnotes

Computer Systems eXercises #3

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Memory and Addressing

1. You are working on your computer and the following ERROR message appears:
   

          FATAL ERROR A227 : EDE0
   

   1. Which section of memory did the error arise (RAM/ROM/VID...?)
   2. How many BYTES above BASE OF MEMORY is this?
   3. How high (in Kilobytes) is this?
   
   
2. Suppose you know that a program you are about to load is EXACTLY 48.5Kb. If it starts loading at the address: 60FEC
   1. What will the address of the LAST BYTE of the program be?
   2. How high will the LAST byte of the program be from the BASE of memory (in Kilobytes please)?
   
   
3. Normalise the following addresses, and state WHERE in memory they lie (ROM, RAM...)
   1. F0D5 : 15EB
   2. D999 : FFFF
   3. 0BC7 : 10E8
   4. C0FF : A07C
   
   
4. If a program starts at the address 0F44B and finishes at the address 90EC1 then
   1. How big is the program (to the nearest Kilobyte)?
   2. How far above base of memory does it start?
   
   
5. Explain why it is necessary to employ schemes such as Segmented Memory Addressing, and suggest ways around the problem that can be implemented at a Hardware level.
   
   
6. Suppose the following OFFSETS all have the SEGMENT B800.
   Rewrite them as segmented memory addresses with a SEGMENT of B000
   1. 0400
   2. 1111
   
   

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Solutions