Author Topic: keyboard issues  (Read 118 times)

Offline vimanas

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keyboard issues
« on: September 05, 2017, 04:42:43 PM »
hello everyone! first real post here, so i hope i'm following all of the proper etiquette.

i've recently restored power mac G4 MDD to full working order and have it integrated nicely into my rig alongside a newer macbook pro as well as a 2006 mac pro. the only snag has come along now that i've tried to clean up some of my cable clutter by utilizing this switch ( to share my keyboard (which is this one: and mouse between all three machines.

everything works wonderfully with the exception of the keyboard - it shows up in the apple system profiler with all of the proper information and is drawing power without issue, but doesn't register any keypresses whatsoever! the keyboard works fine with my other machines, so i can't quite tell if the problem is on the mac side or on the keyboard side.

here's info about my system (assuming this is needed for proper diagnosis)
serial number: XB32524GPC1
Mac OS 9.2.2
Machine ID: 406
Model Name: PowerMac 3,6
PowerPC G4 1.25 Ghz
1.25GB RAM installed

as far as extensions go, all i've got enabled beyond those included with the OS 9 install provided on this site is USB Overdrive.

thanks for any assistance!

Offline GaryN

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Re: keyboard issues
« Reply #1 on: September 05, 2017, 10:06:47 PM »
This is a toss-up. The kbd, the IOGear and USB Overdrive…all three are suspect.
You need to do some process of elimination here.
You have what is essentially a PC keyboard. It normally needs to be "identified" by the OS as a "not-a-Mac-but-compatible" device.
Question: Do you have any version of OSX installed along with OS9? If so, does the kbd work there?

For now, let's assume it's OS9-only:
Does the kbd work plugged in directly without the IO switch?
   If yes, do-h! - you just found the culprit. Probably something to do with USB1 vs. USB2
   If no, check that you have "USB Device Extension" 1.5.9 or better in the active extensions folder.

Work now?
   Yes: Cool.
   No: Disable USB Overdrive restart

Work now?
   Yes: Ouch! Make sure only USB Mouse Overdrive is on and Joystick Overdrive is off.
   No:  Hmmm…

There's a fair possibility that you need to have the kbd connected to the MDD during boot. That's the only time the OS "looks" at the port to see what's there.
If it finds nothing at boot, it defaults to the original Macintosh layout although it would seem that at least some key or two would work anyway.

OK… so after all of that quality deduction time, I went back and followed the Amazon listing all the way to the bottom, where I found:

"NKRO&Full Speed
It adopts standard 104 keys and N key rollover; with built-in 64K flash SCM , and be of full 12Mbps transmission speed, which make the operation much faster."

That's 12Mbps as in the absolute maximum for USB 1.1. Your kbd is spitting data at a rate expected of a USB1 disk drive.
Since there's no "handshake" or such to tell the MDD it's actually just a keyboard, your MDD can't understand what it's seeing - it's gobbledegook.

The solution:
Get a USB2 PCI card and plug the keyboard in there. Will that work?…… Certainly probably… Well worth a try 'cause they're dirt cheap.
That means, of course, that you can't do any special boot-ups (like a desktop rebuild) where you hold a key combo down during boot because nothing will be seen until after the PCI interface is loaded but I assume you still have the old keyboard for that and that's only a once-in-a-while thing anyway…unless you heve OSX on there and you want to option-select it at startup sometimes so then you can keep the old keyboard tucked behind the MDD, yada, yada, yada

Well that was fun…

Offline vimanas

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Re: keyboard issues
« Reply #2 on: September 11, 2017, 07:21:22 PM »
GaryN = God-tier response. Many thanks!

This is wonderfully useful stuff - wasn't aware of the limitations of early USB technology - didn't realize how easy it was to push it to the limit!

I'll invest in a PCI card and report back my findings.

Thanks again!