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 on that material. The format will be similar to the first exam. It will cover lecture material through Chapter 5 in the text and through Program 6.

This test does not cover external linkage, which will be on the final exam after we have more practice with it.

Additional RR and RX Instructions

• 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

• 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?

Subroutines

For this exam you only need to know about internal subroutines.

For 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.

Table Processing

• 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

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.

Old stuff

This test may include some material that was on the previous test, such as encoding and decoding and debugging. In particular, with packed decimal instructions we have to worry about data exceptions.