On Mon, 28 Jun 1999, Mike Naberezny wrote: > > I read about the plans to upgrade the Sound Expander to use OPL2 or OPL3 > > chips. The chip source would be old Soundblaster cards or compatibles. > > Why not make an interface to allow the Soundblaster card being plugged > > into the C64 expansion port? I don't think that much would be needed: > > Maybe a 14.xxx MHz clock source, some logic glue to convert some bus > > signals and of course the OPL2/3 address had to be mapped somewhat to > > make the SB Sound Expander compatible. As a bonus some future > > applications could even make use of the ADC and DAC on the SB card. > > This may certainly be a possibility. I once wired up an old PC internal > modem to my C64's expansion port. All I did was provide the necessary > voltages and a little "glue" map the onboard UART into the $DE00 space. > Probably the biggest problem with interfacing to a Sound Blaster card > would be writing the software. Well the idea of a compatible implementation would be that there would already be at least some software, Commodore's own software for the YM3526 OPL, which would be upwards-compatible with the hacked Soundblaster interface. Anyway, time for an update: I've succeeded in finding one YMF262 chip, in the sound card in this computer, but unfortunately it's SMT. There is also a YAC512 and an 071 quad op-am in SMT. Ideally I need another YAC512 and 071 to make a four channel system, but the biggest problem is desoldering them. There has been some progress on the reverse-engineering front, and I can say that the final schematic is going to surprise many people - there have certainly been some surprises for me! The Yamaha chip's interface is a bit odd and some might say wacky, but much of this is dictated by the presence of both /READ and /WRITE lines on the chip. Anyway, there will be no problem from a schematic point-of-view upgrading to an OPL3, even if the actual soldering job is a pain in the **** ! For those of you interested in the software interface of the OPL3, here is a very good page I found which should be used in conjuction with Yamaha's own PDF file (YMF262.PDF) http://www.fee.vutbr.cz/~arnost/opl/opl3.html There are also OPL2 docs at that site, though I haven't had a chance to compare them with the usual Adlib/Soundblaster site. Anyway, to sum up I should say that the finished OPL3 card will have 5 registers not 4 as in the PC implementation for much the same reason that the current Sound Expander has 3 registers rather than the PC's two. (to do with the seperate /READ and /WRITE lines) Does anyone know of any good OPL3 music software? (with source) The easiest thing to do would be a port from PC to C64. Still on target for a Friday release, btw ;) Richard - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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