Ffaesim

Summary: FFEASIM is a software simulator designed for PDP-12 users to run the Fast Fourier Transform program (FFTD) without requiring the hardware Extended Arithmetic Element (EAE) option. It functions by patching the FFTD program and using a modified version of the "Digital-8-17-U" simulator.

Key details include:

• Performance: Transformation using this simulator is approximately 6.5 times slower than with the EAE option (processing 1024 values in about 30 seconds).
• Operation: It simulates specific EAE instructions (MQL, DVI, MUY, SHL, ASR, LSR, MQA) using software routines, a pseudo-MQ register, and a pseudo-stepcounter.
• Requirements: It must be loaded in a specific order with the FFTD binary using DIAL-MS. The document provides detailed storage locations, usage commands, and a full source code listing for the simulator and the necessary patches.