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by keli
Thu Oct 31, 2019 8:18 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

Here's my latest attempt at doing this correctly. This version should be able to add 3 additional YM chips for a total of 12 audio channels! The first extra chip should replace it's DA4 pin connection with DA4_FLIPPED, the second should connect its DA5 pin to DA5_FLIPPED, and the third one should co...
by keli
Thu Oct 31, 2019 7:36 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

Yes the YM knows and disables its output, but the buffer used for data reads does not and will drive possibly random data onto the 68000 data bus, as its input will be left floating. That's why I suggested using an analog switch instead for both data reads and writes instead of the tri-state buffers...
by keli
Thu Oct 31, 2019 12:15 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

Don't you need to memorize which chip got selected (i.e. having that latch somewhere) so when you do register write, the data goes to the correct chip? Or is a bus buffer also memorizing previous state? All 8 address bits are latched inside the YM, so there is no need to store them externally. The ...
by keli
Wed Oct 30, 2019 10:37 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

Don't you need to memorize which chip got selected (i.e. having that latch somewhere) so when you do register write, the data goes to the correct chip? Or is a bus buffer also memorizing previous state? All 8 address bits are latched inside the YM, so there is no need to store them externally. The ...
by keli
Wed Oct 30, 2019 10:08 pm
Forum: SOFTWARE
Topic: When running EmuTos with NVDI I've noticed a lot of system files...
Replies: 18
Views: 2366

Re: When running EmuTos with NVDI I've noticed a lot of system files...

Yes definitiely some Windows sytem folders. If I remember correctly, the TOS desktop hides files that have the "system" file attribute set on them, whereas EmuTOS's desk ignores the attribute completely and happily shows them to the unexpecting user.
by keli
Wed Oct 30, 2019 9:30 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

.... and before I go to bed, here's a solution that uses a 2 to 4 decoder (with inverted outputs) instead of a bunch of nand gates to decode the bus control signals:
dual_ym_alt.png
dual_ym_alt.png (25.29 KiB) Viewed 792 times
by keli
Wed Oct 30, 2019 8:38 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

Due to the YM going high-impedance when the register address is not correct, the circuit can be much simpler. Leave the original YM (YM0) connected as-is Invert bit 4 on YM1 when BDIR and BC1 are both 1, Connect DA0-3, DA5-7, BDIR, BC1-2, A8, ~A9, etc of YM1 to the same pins as YM0. (the GPIO and an...
by keli
Wed Oct 30, 2019 6:55 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

Reading the data sheet for the AY-8910 , it seems that General Instrument had a similar scheme in mind: The four low order address bits select one of the 16 registers (R0-R17(base 8)). The six* high order address bits function as "chip selects" to control the tri-state bidirectional buffers (when th...
by keli
Tue Oct 29, 2019 6:50 pm
Forum: HARDWARE DISCUSSIONS
Topic: Put 2 YM2149 into the ST
Replies: 38
Views: 4692

Re: Put 2 YM2149 into the ST

They are driven via a LS02, from SND_CS (GLUE) , RW (CPU), A1 (CPU) Capture.JPG Hmm does the SND_CS output depend on the LDS abd UDS signals from the CPU? If not, could these be combined with SND_CS to put the second YM chip on the odd byte of the same address (Wen LDS is active). So the address ma...
by keli
Sun Oct 27, 2019 11:05 am
Forum: HARDWARE DISCUSSIONS
Topic: Recording Audio from the Atari STFM's sound chip.
Replies: 15
Views: 1353

Re: Recording Audio from the Atari STFM's sound chip.

:D
exxos wrote:
Sun Oct 27, 2019 10:23 am
YM chip has 3 channels in fact. So you have chose a channel and split the track and run it to its own audio amp.

If you're going to use it in a modern composition, you might as well record each of the three channels onto its own audio track. Then you are free to mix it as you like.

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