On 5/11/15 4:00 AM, Michał Pleban wrote: > Good observation! I think the only problem will be the TOD of the > CBM-II's will be off, I can live with that. CBM-II machines configure the TOD clock for 50 or 60 Hz automatically. The 50/60 Hz signal is derived from the mains power inside the switching power supply. The power supply output cable has a 6-pin connector that plugs into the mainboard. The 50/60 Hz signal is pin 1 on that connector. The signal is inverted and then goes to a 6525 TPI's IRQ0 and a 6526 CIA's TOD. On power up, the CBM-II KERNAL routine IOINIT waits for the 50/60 Hz signal to change and then increments a counter until the signal changes again. It compares the count against a threshold to detect 50 or 60 Hz and then sets the TODIN bit in CIA 2's Control Register A ($DC0E). If bit 7 of $DC0E is set, 50 Hz was detected. Regards, Mike -- Mike Naberezny (email@example.com) http://6502.org Message was sent through the cbm-hackers mailing listReceived on 2015-05-11 16:01:18
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