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It's a 4-layer board, where the two internal layers are likely power and ground and the two external layers contain the signal traces that you can see. Pin 7 is connected to the ground layer, and pin 14 is connected to the power layer. The two decoupling capacitors C1 and C2 are also connected...

No, pins 1, 2, 3, 4, 7, and 14 are all used (look at the back of the board). It doesn't make sense to use pin 1 without pin 2 or pin 3 without pin 4 as 2 & 4 are the outputs for 1 & 3: On this board, pins 1 and 3 are both connected to pin B7 of the male PDS connector that plugs in to the...

Kai appears to be correct here. I can't see or access the other row of pads that I suspect is under U2, but I'm certain that's what those visible pads are for. The pinouts of the DIP and SOIC versions of the 74F04 are identical: https://www.mouser.com/catalog/specsheets/74F04.pdf Just like...

These?

Interesting. The hole pattern doesn't match the placement of the screws that hold the two halves of a MacCharlie together, and even if they did, directly screwing a MacCharlie to the side using the existing holes seems impractical (screws would have to go through from the inside of the Mac's...

Ya, I'm not going to let this one be the guinea pig 😳 Do you remember the part #'s of the ROMs on the mainboard?

The keyboard extension doesn't have a ROM in it, but it does have a P8748H microcontroller in it as pictured in this post above. I don't know if there's a way to dump the microcontroller's programming: Here's a picture of my MacCharlie's mainboard. As you can see, I have V3 of the Charlie...

Thank you! That video was very helpful! I just wanted the Mac and MacCharlie to line up properly, and I think I worked out that the Mac needed to be raised 16mm to make that happen. So, I just printed four quick-and-dirty risers for the Mac's feet to sit on: My printer isn't big enough to...

I don't have the bottom tray, but I 3D printed some risers for under the Mac's feet to raise it to the same height it would be at if sitting on the tray. That's why the Mac and MacCharlie line up vertically in my picture. When you have the tray, I believe the MacCharlie unit itself is still...

Here's the whole enchilada running Hitchhiker's Guide to the Galaxy from the B drive: Also, I love this cheeky error message:

Thanks! I'd already found the software here and got it booting into DOS 3.10, but it looks like you have a couple things that site doesn't have (y) I've been working on replacing the bad key switches in the keyboard extension, and the TLDR is that I was eventually successful. The PCB is...

Are these photos sufficient? I can also just tell you pretty much how it works (LC PDS pinout for reference): Every PDS slot pin except for C16M (16Mhz clock) at pin B7 is wired straight-through to both female slots on the riser. C16M is connected to the inputs of two separate inverters in...

An unnecessarily complicated Apple //e...

I recently acquired a MacCharlie with the keyboard extension, and I've been talking to @Tashtari about figuring out how it works. However, I've identified TEN bad key switches on it (no continuity across the pins when pressing the key). I know I can just manually short a key when eventually...

I have zero PCB layout/design experience, and you wouldn't be able to use this in a regular LC pizzabox...at least not with the lid on. I also suspect it will only work with either very simple, or very specific accelerators. Still, there's nothing programmable on it, so figuring out the...

It took me 3 years, but I believe I've finally found the dual-slot PDS adapter that was an option with the Power Workstation: There's no programmable logic on it...just a single hex inverter, and near as I can tell, none of the inverted signals are actually used. Only two of the...

I...do not have a thermal camera 😕

That was my thinking. With the particular cards I have installed, the section of the case exhausted by the 40mm fan is mostly walled-off from the rest of the case interior, so the PSU fan probably wasn't that involved in ventilating that area. There are slits in the case lid above the NuBus...

I don't know how useful this'll be for others since it's a pretty specific use-case, but I have a couple extra toasty full-length cards in my IIci, and I was trying to come up with a way to get some air moving through that walled-off part of the case. Since these particular cards don't require...

I'm sure others were probably already aware of this, though maybe had never tried it on real hardware, but I was happy to discover that BlueSCSI's floppy emulation happily mounts 2.88MB floppy images created from flux dumps, so now there's a decent archival path for 2.88MB NeXT floppies...