Transaction Managemen t Facility returns data to a consisten t state by reapplying all committed transactions in the log ￿le to the c heckpoint presented by the backup tape. This is called "rollforward recovery."

Transaction logging requires little CPU o verhead because it is designed as an in tegral part of the MPE/iX File System, utilizing the addressing and protection features of HP Precision Architecture (HP-PA).

Simplifying a Program

The Transaction Managemen t Facility simpli￿es dev elopment and maintenance of transaction-orien ted applications b y:

Maintaining recovery routines, so a programmer does not ha ve to develop and main tain custom ones.

Simplifying the programming task of ensuring data in tegrity and increasing its e￿ciency .

Providing locking and logging, th us requiring the programmer to mark only the beginning and end of transactions.

DEBUG

DEBUG is a low-level assembly language debugger, requiring some kno wledge and familiarit y in the following areas to utilize:

Assembly code

Procedure calling con ventions

Parameter passing con ventions

HP3000 and HP Precision Arc hitecture (HP-PA)

Hewlett-Packard o￿ers two source level, symbolic debuggers, SYMBOLIC DEBUG/XL and Toolset/XL, whic h you can use if you do not require assem bly language debugger features.

DEBUG is an intrinsic procedure, pro viding privileged and non-privileged users with an interactive debugging facilit y for checking out their operating en vironments. Using DEBUG, it is possible to:

Set, delete, and list breakpoin ts in a program. The program executes un til a breakpoin t is reached, then stops and passes con trol to the user. When y ou set breakpoin ts, you can specify a list of commands that will automatically be executed when the breakpoin t is hit.

Single step (multiple steps) through a program.

Display and/or modify the con tents of memory locations. A full set of addressing modes is o￿ered, including:

-absolute CM memory

-code segment relative

-data segment relative

-S relative

-Q relative

-DB relative

-HP-PA virtual addresses

-HP-PA real memory addresses

OVERVIEW 1-11