Freebee Fremium Production Release

I've spent a week or so of my holidays getting the Freebee Fremium design ready to go out. I am hoping that the changes I've made to speed up video RAM access work without a further respin, so have done all the little clean-up bits that one does in moving from prototype to production. Most of the changes are subtle, intended to improve buildability, such as:

• Adding part descriptiors under all the ICs, and in lovely inverse font too.
• Moving the two keyboard scanning ICs up just a little, to give a bit more gap to the keyboard stabilisation bar.
• Cleaning up the designators for the jumpers, so they're from A-Y across the board, making them a lot easier to find.
• Integrating a tiny speaker on the PCB.
• Adding a QR code with a link to the design files.
• Rationalising the number of decoupling capacitors, plus moving 100nF ones to spots where they'll do the most good.

In terms of actual changes to the way the machine works, we have:

• The improvements to CPU video access, as discussed previously.
• Bringing the BSTB and BRDY signals from the PIO out to the GPIO connector in addition to the ASTB and ARDY signals plus port A0-A7. This subtle change allows using the GPIO connector as a high-speed synchronous bidirectional port, using PIO mode 2. I've got this idea for plugging things (generally involving an Arduino Nano) into the GPIO port that allows such things as super fast USB comms with a computer, SD card interface, etc etc. However as the Arduino Nano is sure to be obsoleted in about five minutes and become impossible to get, I don't want to design that onto the main board.
• Allowing the machine to invert VSYNC, by simply changing the video starting address in the CRTC (much as is done for small fonts). This gives us the ability to pretend our video is EGA rather than CGA. Without changing our dot clock to 16.257 MHz we can't make full EGA resolution, but we do (I think!) have enough video speed at 13.5 MHz to do a 466 x 350 (58 x 25 characters with an 8 x 14 font). This is actually kinda special, as this means the pixels are pretty close to square.
• A caps lock LED. I just connected this to LV6, an unused port bit.

There's also a couple of small mechanical changes, mainly around pushing the DIN connector back a few millimetres to get it in line with the D connectors. This necessitated making the PCB a bit bigger, and adding small notches to clear the tabs either side of the DIN connector on the Microbee case. I suspect that Applied Tech originally planned to do just this, but the cost of putting the notches in to the PCB put a kaibosh on that, and instead they just moved the DIN connector back into the case a bit.

A couple of screen grabs of the 3D model:

And the schematic pages:

Design files are on my google drive.