base:efficient_tod_initialisation
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
base:efficient_tod_initialisation [2019-05-17 12:58] – [Dual purpose] silverdr | base:efficient_tod_initialisation [2020-01-31 17:49] – [Proper solution] silverdr | ||
---|---|---|---|
Line 45: | Line 45: | ||
which correspond to the four possible C64 hardware setup combinations. Comparing to $51, which falls more or less in the middle, gives us the expected answer. If the HI byte of the timer has value higher than $51 we have 60Hz supplied to the TOD pin. If OTOH it has lower value, we have 50Hz supplied. | which correspond to the four possible C64 hardware setup combinations. Comparing to $51, which falls more or less in the middle, gives us the expected answer. If the HI byte of the timer has value higher than $51 we have 60Hz supplied to the TOD pin. If OTOH it has lower value, we have 50Hz supplied. | ||
- | Please also note that we use CIA #2 and not CIA #1. CIA #2 is chosen because | + | Advantages: |
+ | * Does not break on Super-CPU and similar | ||
+ | * No screen side-effects | ||
+ | * Short and fast | ||
+ | |||
+ | Please also note that we use CIA #2 and not CIA #1. CIA #2 is chosen because | ||
===== Dual purpose ===== | ===== Dual purpose ===== | ||
I mentioned before that this routine can serve also another purpose and give us potentially even more savings. Yes, with addition of only a few bytes: | I mentioned before that this routine can serve also another purpose and give us potentially even more savings. Yes, with addition of only a few bytes: |
base/efficient_tod_initialisation.txt · Last modified: 2020-10-27 02:31 by silverdr