Danny Tervooren

CS-005-1

Assignment #3

9/26/06

Ch. 5: 2, 9, 15, 16

Ch. 6: 4, 6, 11, 15, 18

 

CH 5

2.)          a.)          20 bits

b.)               24 bits

c.)                27 bits

d.)               30 bits

9.)          The multiplexor circuit would need twenty input lines numbered 0-19

15.)        a.)          26 = 64 operation codes

               b.)          218 = 262,144 bytes

c.)                6+18+18 = 42/8 = 5.25 = 6 bytes

16.)        a.)          0            LOAD                202

                              1             SUBTRACT    203

                              2            ADD                   204

                              3            STORE              200

               b.)          0            LOAD                201

                              1             ADD                   202

                              2            STORE              201

                              3            LOAD                203

                              4            ADD                   204

                              5            STORE              203

                              6            LOAD                201

                              7            SUBTRACT    203

                              8            STORE              200

               c.)          0            COMPARE      200, 202

                              1             JUMPLT           5

                              2            LOAD                203

                              3            STORE              202

                              4            JUMP                 7

                              5            LOAD                204

                              6            STORE              202

                              7

               d.)          0            COMPARE      203, 204

                              1             JUMPGT           9

                              2            LOAD                203

                              3            ADD                   201

                              4            ADD                   204

                              5            STORE              203

                              6            LOAD                204

                              7            ADD                   200

                              8            STORE              204

                              9

CH 6

4.)          a.)          R: 472                60: 472              61: -1

               b.)          R: 472                60: 472              61: -1

               c.)          R: 944                60: 472              61: -1

               d.)          R: 944                60: 472              61: -1

               e.)          R: 944                60: 472              61: 50

               f.)           R: 944                60: 472              61: 50

6.)          If we accidentally executed the data: .DATA 16387, the binary representation of 16,387 would be put into the 12-bit address and spill into the 4 bits of the op code, resulting in the machine language instruction 0010 000000000011.  This would effectively tell the machine to clear (0010) the decimal number positive 3 (000000000011).

11.)        The statement CLEAR SUM in line 2 is necessary, as there may be a running sum left in the program from the last time it was run (if it has been run before).  The statement LOAD ZERO is also necessary, as there may be a value already existing in register R.

15.)        AGAIN:             3

               ANS:                   8

               X:                          9

               ONE:                   10

18.)        In case of memory loss/erasure in machine operator due to various conditions (e.g., synapse-damaging concussion, death, simple forgetfulness, etc.), information may be irrecoverable without the forgotten password.  Furthermore, passwords can be hacked without extreme difficult on the part of skilled hackers, resulting in undesired information loss and crude messages, such as, ÒYouÕve been h4x0rÕd.Ó  Possible alternative means of access limitation may include data encryption with decoders given to those authorized to access the information, or thumbprint/retinal scan matching to ensure authorized access.  Such safeguards would be appropriate in applications for which the value of safeguarding the information exceeds the cost of implementing its safeguarding (issues of national security/public safety, banking, etc.).