Getting G3 Whisper Perch USB working

[Phipli]

Resistors have their values written on them (nnx or nnnx, where n are the start of the value and x is the number of trailing zeros (so 220 is 22 Ohm, not 220 ohm)), so if you beep out the circuit on your pci card you can work out what is connected where, then compare with the personality card and fit the same values in the same places. Where there are gaps, we can compare with iMacs and B&W G3s.

Caps are more tricky because they often aren't labelled. Some will be just isolation caps and we can pick reasonable values, others will need measuring.

 

[croissantking]

Here's an updated schematic, it's more or less complete.
U9 is clearly an overcurrent protection chip. U20 and the associated passives I do not understand their purpose at all, if it's overcurrent protection then why is it connected up to a data line D- rather than VBUS?
It's 3am, I really need to go to bed now

 

[Phipli]

U20 and the associated passives I do not understand their purpose at all, if it's overcurrent protection then why is it connected up to a data line D- rather than VBUS?

Soft power. It goes to both the usb chip (data) and the logic board.

That's my guess.

 

[Phipli]

F1 is the overcurrent protection and LP1 is the transient suppression on the data lines.

Surprised there isn't some kind of over voltage protection on the data lines, but perhaps it wasn't needed.

 

[Phipli]

C106 can just be a 0.1uF capacitor. The exact value isn't critical and 0.1uF is reasonable.

 

[mg.man]

Soft power. It goes to both the usb chip (data) and the logic board.

Just a wild guess... the original iMac [USB] keyboard had a power button - I've used one of these on a B&W G3 and it works. I wonder if Apple was considering accommodating this? Could there have been a prototype "beige" keyboard? Or were they using the G3MT/DT as a development platforms for future USB use?

 

[croissantking]

Just a wild guess... the original iMac [USB] keyboard had a power button - I've used one of these on a B&W G3 and it works. I wonder if Apple was considering accommodating this? Could there have been a prototype "beige" keyboard? Or were they using the G3MT/DT as a development platforms for future USB use?

Probably. I’ve bought a USB keyboard with a power button with the vague intention of testing this out. But, I’m not that bothered about soft power really. Even if it worked, the keyboard would be non-functional until the USB extensions load up; so an ADB keyboard is always going to be a better pairing.

 

[Phipli]

Even if it worked, the keyboard would be non-functional until the USB extensions load up; so an ADB keyboard is always going to be a better pairing.

How does that work on early iMacs if you want open firmware? Surely in that instance USB worked before the extensions loaded? Do you have a Rev C ROM in your Beige G3.

I know that USB didn't work before the extension in older machines, I was just wondering if given they have a USB port, late Beige G3s accommodated it.

Note the 9700 prototype with the USB personality card supposedly supports soft power is why I guess that circuit is soft power.

 

[mg.man]

Note the 9700 prototype with the USB personality card

Interesting you should mention. There's a guy here in the UK with a 9700 [PEx?] - @jimjamyahauk. I know, because I ferried some ROMs across from the US for him. @jimjamyahauk - does your PEx have a personality card? If so, does it have the USB port?

 

[croissantking]

How does that work on early iMacs if you want open firmware? Surely in that instance USB worked before the extensions loaded? Do you have a Rev C ROM in your Beige G3.

I know that USB didn't work before the extension in older machines, I was just wondering if given they have a USB port, late Beige G3s accommodated it.

Yes, I have a Rev C ROM, but I think it’s likely a moot point. In the same machine with a USB PCI card installed, a mouse that’s connected won’t start working until the extensions load.

This is where I think the old world/new world ROM divide starts to become relevant.

I’d assume there are some basic HID drivers in ROM in the early iMacs to allow for basic mouse and keyboard input before extensions load.

 

[croissantking]

Unless… and this is just crazy thinking, but hear me out, that ‘soft power’ circuit we’re looking at actually somehow facilitates mouse and keyboard input before extensions load.

 

[zefrenchtoon]

Probably. I’ve bought a USB keyboard with a power button with the vague intention of testing this out. But, I’m not that bothered about soft power really. Even if it worked, the keyboard would be non-functional until the USB extensions load up; so an ADB keyboard is always going to be a better pairing.

Sorry, this is in French but here is the explanation of how it worked:

Le bouton d'allumage des claviers USB : comment ça marchait ? - Le journal du lapin

Le journal du lapin, mon espace personnel ou je parle de trucs retro, d'expérimentations et de produits Apple. Et évidemment de prototypes.

www.journaldulapin.com

 

[croissantking]

Sorry, this is in French but here is the explanation of how it worked:

Le bouton d'allumage des claviers USB : comment ça marchait ? - Le journal du lapin

Le journal du lapin, mon espace personnel ou je parle de trucs retro, d'expérimentations et de produits Apple. Et évidemment de prototypes.

www.journaldulapin.com

Thanks! I was trying to find an explanation earlier but came up with nothing.

From the page: “Basically, the Macs fed one of the data lines (10 mA) and cutting it with a switch triggered the Mac to turn on.”

And: “take a USB cable, cut it and connect a switch to the white wire (D-) and the black wire (ground)”

This mystery circuit is connected to D- on my Whisper card, so I think @Phipli hit the nail on the head when he suggested it was for soft power.

 

[Phipli]

Sorry, this is in French but here is the explanation of how it worked:

Le bouton d'allumage des claviers USB : comment ça marchait ? - Le journal du lapin

Le journal du lapin, mon espace personnel ou je parle de trucs retro, d'expérimentations et de produits Apple. Et évidemment de prototypes.

www.journaldulapin.com

They link to this : https://www.instructables.com/Intro-31/#step4

which shows them shorting D- to the shield. D- is the wire connected to the circuit we suspect is soft power.

 

[croissantking]

Interesting you should mention. There's a guy here in the UK with a 9700 [PEx?] - @jimjamyahauk. I know, because I ferried some ROMs across from the US for him. @jimjamyahauk - does your PEx have a personality card? If so, does it have the USB port?

Hah, would be good to get photos of the prototype card. Though I’ll admit I’ve been enjoying the puzzle of solving it from scratch.

 

[joevt]

Regarding USB support in Open Firmware,

Old World Macs that came with G3 processors (Beige G3, PowerBook G3 Wallstreet, Power Express) know about USB PCI class code but don't have any USB code.

Only New World Macs (starting from B&W G3) have a usb-probe method.

Of the New World Macs, all except B&W G3 have usb-ms-class. I assume that's for mass storage devices. Does that mean only the B&W G3 can't boot from USB?

I only have 11 New World Mac ROM dumps (decompressed, disassembled, detokenized, and converted to Forth) so I may have missed some. For example, I don't have the one for Yikes G4 so I don't know if its ROM is newer than the B&W G3.

It should be possible to add USB support by porting the USB code from newer Open Firmware to older Open Firmware, add some patches, load the blob from a supported ATA or SCSI disk partition (if not modifying the actual ROM), and execute it to make the patches. I would need to update my fcode tokenizer to handle some Mac stuff.

 

[croissantking]

Only New World Macs (starting from B&W G3) have a usb-probe method.

Of the New World Macs, all except B&W G3 have usb-ms-class. I assume that's for mass storage devices. Does that mean only the B&W G3 can't boot from USB?

What about the Rev. A iMac? This was the first New World Mac, right? Assume the same applies to it as to the B&W G3.

 

[zefrenchtoon]

For example, I don't have the one for Yikes G4 so I don't know if its ROM is newer than the B&W G3.

If you tell me how to, I can dump mine for you.

 

[croissantking]

I've populated some more of the card tonight - the passives highlighted in green. It hasn't made any difference. The only other crucial part now, I think, is the oscillator.

One thing I've realised is that my other PCI USB cards no longer work - they are not even seen as USB cards anymore, just as unknown PCI devices. It might be a case of either/or if I get the Perch USB working.

 

[Phipli]

View attachment 53862

I've populated some more of the card tonight - the passives highlighted in green. It hasn't made any difference. The only other crucial part now, I think, is the oscillator.

One thing I've realised is that my other PCI USB cards no longer work - they are not even seen as USB cards anymore, just as unknown PCI devices. It might be a case of either/or if I get the Perch USB working.

What's the component at F1?