Implementation of the Am9511 Arithmetic Processing Unit into a typical microprocessor system

The Advanced Micro Devices' Am95ll Arithmetic Processing Unit (APU) and its implementation into a typical microprocessor system, in this case, the Motorola M6800 System, are described. A description of the Am95ll, covering its internal configuration, the commands it can execute, the data formats required by these commands, and how to address the APU within the system are presented. The M6800 Central Processing Unit (CPU) is covered, along with a description of the 32K RAM memory board and the logic which connects the Am95ll to the system. .The routines written for program interface with the Am95ll are described. These include utility routines to perform all stack load and unload, stack manipulation, and command execution operations individually, and the completeoperation routines to stack the necessary operand(s), execute the desired command, retrieve the result, and perform limited error analysis and recovery, all in one routine. A problem was encountered when a log of zero was attempted. The required fix-up procedure is described. Detailed information on the APU commands and the access routines are also included, with listings of each command, its hexadecimal code, its function, input requirements, possible errors, and effect on the APU stack; flow charts instruction set, is presented and a listing of each routine, written in the M6800 of each routine written to access the APU are included.