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Always impressive, nice job ! Shooting ideas - I've had capacitance issue with some level shifters. They get noisy on all the bus, not sure you have some in there - weak pulldown on /STERM ? (like 10-47k ?). How low is the voltage going ? Maybe some EMI issue ? The IIsi developer notes states...

They are kinda rare, mostly used in classrooms back then. Wouldn't be too hard to reproduce tho if someone can draw the schematics

Doesn't it need a 74 series something chip as well to fix the chip select ?

Good old cat /dev/sda | netcat ?

Add like 10-100nF caps from TxD+ to GND (serial) and TxD- to GND (serial). Don't see why that wouldn't work, unless the PIC power consumption is > 1 mA

@joshc nice, good job ! It will fit nicely with your translucent SE/30 :)

@jmac they are not used much. The controller blink them after initialization and that's about it. IIRC, the one under Power is actually "Num lock" and the other one is "Scroll lock". Like on a real Mac, these LEDs are not very useful. You can make them blink with something like ADB Express...

@Phipli that was for me. Thanks again :) I ended up building a prototype with the schematics from MacGarden. It didn't work, but may be an error on my part (not working = not visible by software) Then someone provided me a real (working) one, and the schematics don't match, different ICs, PIN...

Nice, good job !

Yes, as most of the SCSI upgrades. Some board asked for Plus ROMs, others had patched 64k ROMs in other way or another. The Beck-Tech MacMEGABYTES used a second set of ROMs to patch the 64k ROMs

The 64k ROM assumes that the max RAM possible is 512. Since video and sound buffers are at the top of memory, this can't work The 68k ROM make the CPU writes at the top of 512kB of RAM, and your logic board video/sound circuit reads at the top of 1024kB of RAM

Missing keys, broken case mostly. Can you see your keyboard with ADBParser ? The three LEDs flashing the first time is a good sign. It means the controller is alive. The LED trick I've seen it fail with working keyboards, don't know why. I will go with either your matrix is fully dead, or it's...

That's the one !

I will switch to a few others projects for now, but maybe someone can take it from here !

Thanks ! I didn't have a blank bracket around but that's a good idea ! The "someone" is me. Don't bother, I found the resistors values. I did this project using your previous pictures, so thanks a lot !

@Mr. Ksoft thank you that did it. It does indeed sounds like the stock game

Some measurements and subjective remarks. This has been benchmarked against a Quadra 650 board (Wombat). I did it to double check something wasn't broken with the daughter board Output levels The last notch on the PAS16 Control Panel volume is an overdrive, 100% volume is last position minus...

Nope, not any better 😕

Thanks a lot ! I would keep the box, the card is more valuable this way, but you do you :) The gerbers files and design has been released on GitHub here Will try to release the measurements this week-end as well