Motorola M68000 User's Guide download pdf (Page 196)

182 Assembly Language Programming for the 68000 Family

3. In what way does the 68010 handle bus errors differently than the

68000?

4. What is the purpose of memory management hardware?

5. What is the most popular form of memory management for imple

menting virtual memory?

6. What is a page fault?

7. What is the purpose of a virtual machine?

8. Is a MOVE from SR instruction privileged on the 68010?

9. Write a 68010 instruction to copy the contents of the CCR to register

DO. This instruction should not generate an exception in user mode.

10. What output lines are provided for reference classifications?

11. What new registers are provided on the 68010 to allow overrides to

the reference classification?

12. Write the instructions necessary to reference absolute location $1000

in the supervisor data space. Read the longword at this location into

13. What is the function of the vector base register?

14. What does the RTD instruction do?

15. What addressing modes are allowed with the single instruction used

inside the loop in loop mode?

Answers

1. A virtual memory is the illusion of a large physical memory when in

actuality a much smaller memory is available.

2. A bus error is an exception that is generated when a reference is made

to non-existent memory.

3. The 68010 allows an instruction to be restarted where it left off after

a bus error is processed. This is accomplished by stacking additional

state information during the exception processing.

4. Memory management hardware provides the necessary mapping be

tween the logical address and the physical address.

5. Paging.

6. A page fault is generated if a memory reference is made to a page

that is currently not in physical memory.

7. A virtual machine can be used to allow execution of several differ

ent operating systems on the same CPU or to provide a simulation

capability for features that don’t actually exist.

8. Yes, but not on the 68000.

9. MOVE CCR,DO

10.

PC0, FC1, and FC2.

1 2 ... 191 192 193 194 195 196 197 198 199 200 201 ... 255 256

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Motorola M68000 User's Guide Page 196