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| Geethree G4+ “Stealth Serial Port” PCI slot bracket |
Posted by: gsteemso on 2025-12-19 08:03:30
Yeah, I thought that IDC header was socketed onto pins too. Alas, it appears to be soldered down, though I suppose it could always just have a “resists tools” level of stiffness. Prying it off would break it either way. I had in mind the technically simpler solution of plugging a miniDIN plug into the existing jack, with a 2–4" pigtail to an already-mounted PCI-bracket miniDIN. |
Posted by: NJRoadfan on 2025-12-21 19:10:06
I guess the PowerMac G5 still retained the SCC core for interfacing with the modem? The developer's notes don't mention this at all.
I don't see much of a point of a stealth serial port vs using a KeySpan USB adapter though. Mac OS X doesn't support LocalTalk, which is pretty much the only advantage this setup has over straight USB adapters. |
Posted by: paws on 2025-12-21 22:01:30
> which is pretty much the only advantage this setup has over straight USB adapters.
On OS 9 machines at least, there's a real difference in timing accuracy when using serial MIDI interfaces compared to USB. So if you're using your Macs to make music with external synthesizers, a serial MIDI interface will give much better results than a USB one. "Some argue" that this is also the case on OS X PPC machines. but I don't know if it's true. |
Posted by: jeremywork on 2025-12-22 12:26:28
> which is pretty much the only advantage this setup has over straight USB adapters.
On OS 9 machines at least, there's a real difference in timing accuracy when using serial MIDI interfaces compared to USB. So if you're using your Macs to make music with external synthesizers, a serial MIDI interface will give much better results than a USB one. "Some argue" that this is also the case on OS X PPC machines. but I don't know if it's true. I haven't experimented much with this, but perhaps Classic environment would retain the advantage if nothing else? |
Posted by: NJRoadfan on 2025-12-22 14:33:27
The Classic environment is notorious for having issues with timing sensitive operations, hence why so many people want machines that can natively boot OS 9. |
Posted by: paws on 2025-12-23 13:02:29
Yeah, Classic isn't useful for anything more advanced than playing back a single sound file.
Also, to be clear, USB MIDI is a lot better on OS X. Good enough for me, certainly. |
Posted by: treellama on 2025-12-23 13:12:44
I've never noticed any difference in USB vs serial in OS 9. Do you have a reference with some measurements? |
Posted by: paws on 2025-12-24 14:23:56
Measurements? Nope. But I have a USB Micro Lite and a serial MIDI Timepiece and the difference was pretty apparent when I compared. Maybe it depends on a number of things. And I think I heard Logic does some special timestamping stuff with Emagic USB interfaces that makes it better. But either way, this is something "people have been saying" since the first iMac came out. So whether or not it's always true, it has been a reason people have sought out the Stealth Serial ports and similar. |
Posted by: Chopsticks on 2025-12-24 16:39:24
there is definitely going to be more latency induced using usb midi interfaces compared to serial based interfaces due to the fact that usb introduced and required a large driver stack (for the time) where as the older printer and serial ports were running as pretty low level direct access hardware from the mac OS. by the time OSX came out serial was in its own kext driver however the overhead was virtually zero latency wise.
as the imac platform developed and the hardware got more powerful these driver overheads began to become a redundant issue.
Also worth pointing out that at some stage between 10.2 jaguar and 10.4 tiger the OS X audio and MIDI stack in the OS got a massive rewrite too that really changed the game. it was around then that the mac platform got a massive boost in use by professionals and studios etc. |
Posted by: adespoton on 2026-01-05 20:01:10
there is definitely going to be more latency induced using usb midi interfaces compared to serial based interfaces due to the fact that usb introduced and required a large driver stack (for the time) where as the older printer and serial ports were running as pretty low level direct access hardware from the mac OS. by the time OSX came out serial was in its own kext driver however the overhead was virtually zero latency wise.
as the imac platform developed and the hardware got more powerful these driver overheads began to become a redundant issue.
Also worth pointing out that at some stage between 10.2 jaguar and 10.4 tiger the OS X audio and MIDI stack in the OS got a massive rewrite too that really changed the game. it was around then that the mac platform got a massive boost in use by professionals and studios etc. Yup; Core Audio got a rework in Panther (10.3). Before that the latency was really annoying for DAW work, which is how the MacOS9Lives! website came to exist -- because a lot of audio professionals stayed on OS 9, even after Jobs performed its funeral.
Personally, I still found the audio stack really annoying until I got my G5 -- at that point, the latency issues were pretty much gone due to a combination of improved software architecture and just plain faster CPU driving USB. The problem before that with USB is that everything had to go through the entire driver stack and then be processed by the CPU and its clock, whereas a Mac Plus was perfectly competent at driving MIDI via something like DMCS out the serial ports with an external clock. |
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