tag:blogger.com,1999:blog-23217409.post4854600457838380329..comments2024-03-15T15:10:58.249+10:30Comments on little-scale: Chiptuning the Atari POKEYSebastian Tomczakhttp://www.blogger.com/profile/12712567577323498804noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-23217409.post-90879834341145107142011-10-25T05:57:26.310+10:302011-10-25T05:57:26.310+10:30The guy is totally just, and there is no skepticis...The guy is totally just, and there is no skepticism.muebles en leonhttp://www.muebles-en-leon.comnoreply@blogger.comtag:blogger.com,1999:blog-23217409.post-65673239133309431922009-01-16T13:52:00.000+10:302009-01-16T13:52:00.000+10:30Have you been doing frequency measurements with th...Have you been doing frequency measurements with the chip itself? Some of your math is a bit off from what I have measured and tested, that's why I ask. The data sheet is misleading in a couple spots and you can end up with worse tuning at high frequencies. <BR/><BR/>Hit me up sometime, I don't know how to get in contact with you : )Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-23217409.post-23922523469183049092009-01-14T20:52:00.000+10:302009-01-14T20:52:00.000+10:30I agree with you that the tuning of a chip gives r...I agree with you that the tuning of a chip gives rise to a unique character that needs to be taken into account with various chips and how they produce a given frequency. <BR/><BR/>"I've heard about some technique involving rapidly changing the frequency register between two values to achieve greater frequency resolution." <BR/><BR/>No no, this is nothing of the sort, it's just that the POKEY has a 16 bit mode that treats two 8 bit registers / voices as a single entity, thereby giving you 16 bits worth of frequency.Sebastian Tomczakhttps://www.blogger.com/profile/12712567577323498804noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-14511728219077547162009-01-14T09:23:00.000+10:302009-01-14T09:23:00.000+10:30Aha, thanks, that makes sense! I've heard about so...Aha, thanks, that makes sense! I've heard about some technique involving rapidly changing the frequency register between two values to achieve greater frequency resolution. On an atari it would eat a lot of time of course, but if you're using a fast microcontroller it might not be that big of a deal to implement (I have no idea though) for your project. I think it was implemented in Raster Music Tracker.<BR/><BR/>Personally I think the off-tune notes add some character to the sound and could be utilized if composers took it into account instead of thinking in terms of 12-tet equal temperament.<BR/><BR/>Good luck!<BR/><BR/>Also, I'm a frequent reader, but I guess I should comment more :)Marcelhttps://www.blogger.com/profile/16671780143487408129noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-61008277483916442822009-01-13T08:32:00.000+10:302009-01-13T08:32:00.000+10:30Hi Boomlinde! Nice to see you in this part of town...Hi Boomlinde! Nice to see you in this part of town. <BR/><BR/>16-bit mode gangs two of the oscillators together, so in effect it takes up two channels instead of just the one.Sebastian Tomczakhttps://www.blogger.com/profile/12712567577323498804noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-39041487456628375522009-01-13T08:27:00.000+10:302009-01-13T08:27:00.000+10:30What is the advantage of using the 8-bit mode as o...What is the advantage of using the 8-bit mode as opposed to 16 bits (except for the gain in free CPU time from reading/writing only one byte)?Marcelhttps://www.blogger.com/profile/16671780143487408129noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-65282809353349958412009-01-09T17:16:00.000+10:302009-01-09T17:16:00.000+10:30hmmm I WONDER WHO THAT WAS?hmmm I WONDER WHO THAT WAS?Sebastian Tomczakhttps://www.blogger.com/profile/12712567577323498804noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-71696897089512280202009-01-09T14:21:00.000+10:302009-01-09T14:21:00.000+10:30nyup nyup nyupnyup nyup nyupAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-23217409.post-62061519702599452009-01-08T20:05:00.000+10:302009-01-08T20:05:00.000+10:30Also: clock for 8 bit mode can be 1,843,200 Hz, 65...Also: clock for 8 bit mode can be 1,843,200 Hz, 65,828.5714285714 Hz or 15,360Hz for a crystal running at 1.8432 MHz. <BR/><BR/>For 16 bit mode it is usually just 1,843,200 HzSebastian Tomczakhttps://www.blogger.com/profile/12712567577323498804noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-59006550341610035962009-01-08T20:03:00.000+10:302009-01-08T20:03:00.000+10:30For 16 bit mode, the calculation is: F = clock / (...For 16 bit mode, the calculation is: <BR/><BR/>F = clock / (2 * (256 * hiB + loB + 7))<BR/><BR/>where hiB = ((clock / F/ 2) - 7) / 256)<BR/>and loB = ((clock/ F / 2) - 7) % 256)<BR/><BR/>For 8 bit mode: <BR/>byte = (clock / F / 2) - 7Sebastian Tomczakhttps://www.blogger.com/profile/12712567577323498804noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-12380739685260997732009-01-08T19:44:00.000+10:302009-01-08T19:44:00.000+10:30What is (are) the formula(e) for Hz->Pokey? I w...What is (are) the formula(e) for Hz->Pokey? I want to test certain calculations...Anonymousnoreply@blogger.com