The machine included a modification that allowed either the original clock (1.7MHz) or a slightly faster clock (2.6MHz) to be routed to the processor. The high speed was enabled at power-up, although that seemed to be a matter of luck as there was no reset on the register. I’ve added a system reset so that it defaults to the normal speed. I suspect that this might be more reliable.
The mod includes a register in I/O space to enable / disable the high speed clock.
OUT 254, 1 --> Changes to the high speed clock
OUT 254, 0 --> Changes to the normal clockThe mod includes a LED to indicate whether “turbo” mode is activated. I’ve added a series connector so that the lid can be separated.