Tracing chains

If you have found the beginning of a longer chain in a dump window and want to trace that chain, the best method of doing this is as follows:

• Keep the beginning of the chain in one dump window (e.g. W4) and assign two free dump windows or windows which are no longer needed (e.g. W6 and W8) by means of the statement
  MODIFY-SCREEN-LAYOUT FIRST=6(SIZE=5), SECOND=8(SIZE=5), THIRD=4

• Mark the first chaining address in W4 with + (the third window on the screen). The marked address appears in window W6.

• Alternately mark the next chaining address in the two upper windows W6 and W8 until the desired address is reached.

This method has the advantage that tracing can be restarted at any time from the previous address or even the first address if you make a mistake.

If this safety precaution is not desired, or if only a certain memory segment in the chaining sequence is needed for further processing, the following method can be used:

• Assign the entire screen to the window in which the first chaining address is displayed (e.g. W4) by means of the statement
  MODIFY-SCREEN-LAYOUT FIRST=4(SIZE=19)

• Mark the chaining address in this (single) window W4 until the desired memory segment is found.

This method ensures that a window whose old contents are needed for further processing is not inadvertently overwritten with the chaining addresses.

Another useful feature is the fact that any DSECT selected for a window remains stored. Consequently, if various elements of the chain are displayed sequentially in the same window, each area is immediately edited in the symbolic format of the selected DSECT.