Previously, I wrote about MicroCore Labs’ cycle-exact MCL65 soft-core version of the venerable 6502 microprocessor, which found its way into many significant microprocessor-based designs in the 1970s, 1980s, and beyond. When I wrote about the core, instantiated in less than 1% of a Xilinx Spartan-7 S50 FPGA, it was operating a Commodore VIC-20 personal computer. (See “Cycle-exact 6502 processor clone fits in 0.77% of a Spartan-7 (and Spartan-3) FPGA, powers VIC-20 PC.”) Now, there’s further evidence of the core’s cycle-exactness: it’s running an Atari 2600 VCS (Video Computer System) and an Apple II personal computer. Both of these machines were introduced in 1977 and both are significant in the context of the MCL65 processor core because both of them rely entirely on instruction-level timing loops for critical functions.