CSCI 360 Exam 2 - Study Guide

Review questions are available on the course home page. Please take some time to review them, as they are representative of what will be on the exam.

As with the programming projects, the tests are also cumulative. You will be responsible for the material presented on the first exam, but you should not expect any direct questions. The format will be similar to the first exam. It will cover lecture material through Chapter 5 in the text and through program 6.

Additional RR and RX Instructions

A couple of new looping instructions have been introduced that you should know.

• Know how to use BCT and BCTR.
• Know when the register is decremented and when the branch is taken.
• Know the type of loop that can be coded using these instructions.
• Know what happens when the second argument of BCTR is 0.

SS, SI, and Character Instructions

There are a couple of SS and SI instructions that we have been using lately that you should know.

• Know how to use MVC and MVI.
• Know how to do comparisons with CLC and CLI.
• Know SS and SI instruction encoding formats. How is the length field encoded???

Internal Subroutines

For this exam you only need to know internal subroutines.

• Know the instruction BAL.
• Know how to define A-type data.
• Know how and when to use STM and LTM.
• Know how to build a parameter list, how to reference it, and how to access and alter items in it.

Sorting

Get ready for sorting, you will do a lot of it in courses to come.

• Know how the selection sort works.

Table Processing

In addition to sorting tables, be familar with the other routines we have been using with tables.

• Be able to BUILD and PRINT tables.
• Know how to update the next available entry address using the parameter list.

The location counter and the ORG statement

Manipulating the location counter can become very handy if you know how to use it correctly. We haven't asked you to use the location counter or write your own ORG in a program, but expect a couple of questions on the test.

• '*' (without quotes) is the notation for the current value of location counter.
• Know the basics for using ORG to alter the location counter.
• Know some situations where you might want to alter the location counter or make a reference to the location counter.

Packed Decimal

Packed decimal numbers are necessary for accurate financial calculations. The packed decimal instructions are complex. It is important to know the details of their operation. Otherwise, be prepared to deal with a lot of 0007 interrupts (S0C7 abends). The text book has an excellent chapter devoted to packed decimal instructions. It would be a good idea to re-read it before the test.

• Know the formats for Zoned and Packed data.
• Be familar with the following instructions: PACK, UNPK, ZAP, AP, SP, CP, MP, DP, SRP, CVB, CVD, ED, EDMK.
• Be able to debug a 0007 interrupt. Know what instructions will cause it, and which ones do not.
• Know the other types of interrupt that can be caused by these instructions.
• Know how to construct edit fields and how to use the ED and EDMK instructions.
• Know how to build replacements for XDECI and XDECO using the CVB and CVD instructions.
• Know how zoned and packed decimal numbers store the sign digit.
• Be able to carry out multiplication, division, addition, and subtraction of packed decimal numbers.
• Know how to shift and round with SRP.
• Know how to define Z, P, and X data.