26-01-2022, 11:26 AM
The earliest known enthusiast microbee hack was a CPU turbo switch allowing it to be boosted from 2MHz to 4MHz.
It was done with kit microbees with the hack comprising of two switches, a PCB track cut, replacement of the Z80 CPU and PIO with 4MHz 'A' versions and replacement of the MWBASIC and FONT ROMs with 250ns versions.
Switch A (SPDT) was used to select the CPU speed of either 2 or 4MHz.
Switch B (SPDT momentary with centre off) was used to invoke the /WAIT signal momentarily prior to changing the position of Switch A.
When in boost mode programs ran twice as fast, however, with the tape, speaker and serial being bit bashed one needed to switch back to normal speed to use them.
It was done with kit microbees with the hack comprising of two switches, a PCB track cut, replacement of the Z80 CPU and PIO with 4MHz 'A' versions and replacement of the MWBASIC and FONT ROMs with 250ns versions.
Switch A (SPDT) was used to select the CPU speed of either 2 or 4MHz.
Switch B (SPDT momentary with centre off) was used to invoke the /WAIT signal momentarily prior to changing the position of Switch A.
When in boost mode programs ran twice as fast, however, with the tape, speaker and serial being bit bashed one needed to switch back to normal speed to use them.
