Computer Organisation I

Exercise 2, 9-12.11.2004

Question 1: High level language vs. assemble language..
Assume that we have program Simple that is written with some high level language (C, Java, Pascal), and that it has been translated into TTK-91 machine language.
What data in program Simple (e.g., variable values) would one want to keep ...
1. in device registers all the time
2. in memory all the time
3. sometimes in device registers and sometimes in memory
4. nowhere (not in the registers or in the memory)
... during program execution? Why? Give examples.
d) is not a trick question!

Question 2: Into symbolic assembly language

Write a TTK-91 symbolic assembly language program that does the same as C program

        
int a=7, c=4, m=15, i=4, i0=4,
    k=0, n=0, j=1, p=0; /* variables a,c, i, i0, k, n, j, p */
main(){               /*main program, basic linear congruential
algorithm */
  scanf("%d", &n);    /* read an integer into n */
  scanf("%d", &p);    /* read an integer into p */
  while (k < n) {
        if (i0 == i)  /* if the value of i0 is same as the value of i
*/
          j=1;
        if (p==1)       /* print only random numbers */
          printf("%d \n", i);  /* print i */
        else
          printf("%d %d %d\n", k, j, i);  /* print k, j, i */
        i = (a * i + c ) % m; /* take module m from expression inside
() */
        k++; j++;      /* increment 1 into k and j */
               }
}

Check your program by compiling and running it in Titokone. Try to give as input for example n=17 and p=1. (Result should be numbers 4 2 3 10 14 12 13 5 9 7 8 0 4 2 3 10 14.)

Question 3: Constants
Constants (e.g., value MAXID=78) can locate in many different places during program execution. Write TTK-91 symbolic assembly language instructions with which one would add value of constant MAXID to R1, and where MAXID value (78) is taken from
1. memory (memory location)
2. register
3. machine instruction
Give an example where case (a) would be best suitable. Similarly, for cases (b) and (c). Give reasoning for your examples.
Question 4: Records and memory references. Communal election register record type has been defined with pseudoinstructions
```
               ; record party:  4 integer fields
               Places  EQU 0    ; relative address within record
               Votes   EQU 1
               Change  EQU 2
               VoteC   EQU 3
   
```
Records SDP and KESK have been allocated from memory with initialized data and record KOK has been allocated partly with uninitialized data with pseudoinstructions
```
	
 SDP     DC  2585    ; Places = 2585
                s1      DC  575822  ; Votes  = 575822
                s2      DC  26      ; Change = 26
                s3      DC  64452   ; VoteC  = 64452
                KESK    DC  4425
                k1      DC  543885
                k2      DC  -200
                k3      DC  15566
                KOK     DC  2078
                kok1    DC  521412
                kok2    DS  1       ; initial values not defined
                kok3    DS  1       ; initial values not defined
    
```
Please notice that you should not use symbols s1, s2, s3, k1, k2,k3, kok1, kok2, and kok3. They have been written down because Titokone simulator gives an error if there is DC without symbolic name in front of it.

Example: If R4 points to the beginning of record SDP, then the change of the places of the party SDP compared to the year 2004 election is obtained to register R5 with machine instruction "LOAD R5, Change(R4)".

Write a TTK-91 symbolic assembly language program to
1. Print the values of all fields in the record pointed by R1, when R1 is first set to point to the record of KESK with machine instruction "LOAD R1, =KESK".
2. Set the field VoteC of KOK to 57919, and set the field Change of KOK so that it will be 24 more than the field Change of SDP. (Count it using your program.)
3. Print the sum of places parties SDP, KESK and KOK got during communal election 2004 and 2000.
4. Print the amount of places that gain the party had the lowest amount of places during communal election in 2000.
Check your program by compiling and running it in Titokone.

Paivi.Kuuppelomakir@cs.helsinki.fi