> This chip was called the AMU (Address Management Unit), and was designed in late ’84 and early ‘85. Since this was before the days of the Verilog Hardware Des

> This chip was called the AMU (Address Management Unit), and was designed in late ’84 and early ‘85. Since this was before the days of the Verilog Hardware Description Language, and there existed no other logical description (other than PAL equations) of the Mac to drive any EDA design or simulation tools, I assisted Bob by writing an event driven cycle accurate simulator in C that took as input the equations that described the behavior of the Mac motherboard signals. These equations (or rules) were parsed by a YACC (Yet Another Compiler Compiler) generated program as part of the simulator. There were “rules” defining internal and output signal behavior. System stimulus was captured using a Tektronix DAS logic analyzer on actual Macs, and then the results of the AMU simulator were compared against captured behavior of real Macs. Wild! For some reason I just assumed everyone was making the world's largest Karnaugh maps before VHDL.