Arduino, SID and LogicDART
Analysing the timing of the simulated 6502 bus cycles with the HP LogicDART. This is roughly the moment when I realised that I would need in-line assembler code to make it go fast enough. The display shows the 1MHz Phase2 signal (lower trace) and the Arduino-generated CS (chip select) signal (upper trace). Doing this in C, via the Arduino IDE, is too slow, taking 220ns to respond to the change in state of the 1MHz signal. Previously, I timed the Arduino 'writeDigital' function at 3.3us just to write CS low and the high again -- this version uses direct port I/O in C and is still too slow.
Arduino, SID and LogicDART
Analysing the timing of the simulated 6502 bus cycles with the HP LogicDART. This is roughly the moment when I realised that I would need in-line assembler code to make it go fast enough. The display shows the 1MHz Phase2 signal (lower trace) and the Arduino-generated CS (chip select) signal (upper trace). Doing this in C, via the Arduino IDE, is too slow, taking 220ns to respond to the change in state of the 1MHz signal. Previously, I timed the Arduino 'writeDigital' function at 3.3us just to write CS low and the high again -- this version uses direct port I/O in C and is still too slow.