cr1901 changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs: https://libera.irclog.whitequark.org/~h~yamahasynths
KDDLB has quit [Quit: Ping timeout (120 seconds)]
KDDLB has joined ##yamahasynths
<Nerionaya>
does anyone here happen to know, did any Genesis 2 models use a discrete YM3438? Or was it always integrated into a custom ASIC
<cr1901>
That is a good question that I don't know the answer to :(
<fseidel>
if there is, I've never seen one. Every model 2 I've ever seen has had an integrated YM3438, or a YM2612
<andlabs>
- YM2612 was used in early consoles (in fact it was the only one available, the Japanese docs have a "preliminary" datasheet)
<andlabs>
- YM3438 was used in the Teradrive, but they added some simple logic in front to fix one of the issues caused by it
<andlabs>
- when the FM chip was integrated into the ASIC (i.e. mainly model 2) the core used was based on the YM3438 (discrete YM3438 was never used on the Mega Drive proper)
<andlabs>
- I think System C may be using YM3438 but I haven't checked for sure
<andlabs>
The difference between YM2612 and YM3438 isn't in the logic itself, but that they're different processes (in particular YM3438 is CMOS) and that changes the behavior of the pins that aren't actively being driven by the chip.
<andlabs>
When reading the FM status, bits 6-2 are not driven at all and the Z80 sees whatever ends up in the open bus (with the discrete YM2612 it's likely whatever was left there by the opcode read, but in later revisions it's more likely to be pulled high instead)
<andlabs>
this was in direct response to the thing about hellfire from the other day btw
<andlabs>
you probably have some level shifting chaos necessary if you want to drop a YM3438 into a genesis without revisions yes
SceneCAT has quit [Read error: Connection reset by peer]
SceneCAT has joined ##yamahasynths
natalie has quit [Ping timeout: 250 seconds]
natalie has joined ##yamahasynths
_whitelogger has joined ##yamahasynths
SceneCAT^APUG has joined ##yamahasynths
alice has joined ##yamahasynths
SceneCAT has quit [Ping timeout: 256 seconds]
__sen_ has joined ##yamahasynths
q3k has quit [Ping timeout: 250 seconds]
__sen has quit [Ping timeout: 250 seconds]
__sen_ is now known as __sen
gruetzkopf has quit [Ping timeout: 250 seconds]
gruetze_ has joined ##yamahasynths
q3k has joined ##yamahasynths
emilazy has joined ##yamahasynths
SEGFAULTLauren[m has joined ##yamahasynths
ricky26 has joined ##yamahasynths
ugla has joined ##yamahasynths
ugla has quit [Remote host closed the connection]
emilazy has quit [Remote host closed the connection]
ricky26 has quit [Read error: Connection reset by peer]
SEGFAULTLauren[m has quit [Remote host closed the connection]
emilazy has joined ##yamahasynths
SEGFAULTLauren[m has joined ##yamahasynths
ricky26 has joined ##yamahasynths
ugla has joined ##yamahasynths
ugla has quit [Remote host closed the connection]
ricky26 has quit [Remote host closed the connection]
SEGFAULTLauren[m has quit [Remote host closed the connection]
emilazy has quit [Remote host closed the connection]
emilazy has joined ##yamahasynths
SEGFAULTLauren[m has joined ##yamahasynths
ricky26 has joined ##yamahasynths
ugla has joined ##yamahasynths
q3k has quit [Changing host]
q3k has joined ##yamahasynths
emilazy has quit [Quit: Client limit exceeded: 20000]
SEGFAULTLauren[m has quit [Quit: Client limit exceeded: 20000]
ricky26 has quit [Quit: Client limit exceeded: 20000]
ugla has quit [Quit: Client limit exceeded: 20000]