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It’s a 50-pin connector for the Classic II FPU Card instead of 44 on the Classic RAM card, I think. Still expensive too, like $10 for the part on his BOM. Garrett has suggested not using equal-ish size right angle connectors but instead using one 2x20 and one 2x2. Sounds odd but his rationale...

@alxlab Are you sure it's gonna be able to be cut with with wire snips? I cut the sort of "perforated" headers but these connectors are all kinda beefy.

Hi everyone. I’ve got another nearly finished project here. This one almost done! I have boards in hand and they have been working in the lab for almost 6 months. I need some testers who have a variety of Apple II family machines to test the cards out on. For those who don't know, "Slinky" or...

I think that given the high prices for the old-style connectors and the fact that the RAM card is so short (and doesn't need too much extra support), we should probably just try and adapt new-manufacture connectors. But which is easier? Sanding off a bit of the edges so they'll fit with the...

@Kai Robinson Here's the closest thing I could find from Samtec: https://www.digikey.com/en/products/detail/samtec-inc/BCS-122-L-D-HE/1100149. $7 though and no stock. It's special order but you can buy singles. @alxlab The molex part is expensive and high MOQ though...

Kai's Mac Classic Reloaded is exciting! I have some chips from bombed SEs which I am anxious to put to use once I have a bit more time and space on the soldering bench. But I feel it would be a big shame if the project sort of went out the door with the original RAM card when we can make...

@alxlab Hmm I have two ideas that should satisfy your desire for attaching SPI peripherals. Keep in mind, the SPI-to-NuBus bridge is designed to connect to master devices on both sides. So the Mac addresses the bus bridge and then the bus bridge is accessed by the ESP32 to get the data out. So...

It would probably be better to move the JTAG, microSD, and USB interfaces onto the dongle board. Then all that needs to go through the connector back to the NuBus card would be power, SPI, and the few utility signals. But is it worth it? It’d be stronger and the rear panel design would be more...

Oops sorry, I didn't directly respond to your point about the connector. The issue is sort of a long distance vs. short distance bus problem. Actually for 80 MHz operation, the ESP32 is as far away from the NuBus interface as it can be. Signals on a PCB propagate at about 0.16 nanoseconds per...

Is it too crazy to put the WiFi module this far out the back of the Mac? Further from the case means better WiFi reception. 1:1 scale (ish) comparison with real NuBus card: Maybe a little less? Right now it sticks out 1" from the board edge. Obviously the board edge is recessed somewhat from...

I have become aware of a new potential gotcha: SPI transfer overhead time on the ESP32. Reports online suggest that "polling" SPI transfers on the ESP32 can take up 5-10 microseconds after the relevant ESP-IDF API call to begin. This is way too much! On a 16 MHz ATMega328 the overhead is just a...

These resources are great! It seems like there are enough examples that we should be able to achieve success, particularly the one from hackster.io which is basically exactly the same program as our desired application. I'm doing the board now: Everything from the schematic is on here plus...

Hmm I think I may have been misremembering about MC68k driving the address bus during reset. Check this diagram from the user's manual: It's more that MC68 might drive the bus before 4 clocks after Vcc has reached minimum operating voltage. Seems explicit that it doesn't drive the bus while...

Yeah, somehow the WiFi to Ethernet bridge has to get the packets received from the ethernet transciever and then retransmit them over WiFi. So it's basically the same software as we need for this but ours has to get the packets from the SPI interface connecting to the Mac instead of the ethernet...

Thanks to @alxlab I know what API I have to implement to do a Mac Ethernet driver. The API is so simple that the message format from the Ethernet driver on the Mac to the software on the ESP32 could just encapsulate the parameter block passed by the client of the Mac Ethernet driver to the...

Yeah basically. /BR low makes MC68k give up the bus after the current /AS cycle. So your hardware can pull /BR low, then wait two clocks (in case MC68k has already decided to start a new bus cycle concurrent with your /BR request). Then you watch for /AS high, indicating that MC68k is done with...

Thank you!!! I will look soon. I forgot about the later IM series. I was looking through the original six, designing cards and drivers, etc.

One of the next steps on my rather tentative ESP32-based network card concept is to figure out what API an Ethernet card has to implement. I haven’t dumped the list of device drivers on one of my Macs with NuBus Ethernet but I suspect that Ethernet driver puts an entry in the system device...

Hmm maybe "exact timing" was too strong a description. It's more like when interrupts are disabled (for floppy or serial access) the Mac has to have some minimum average performance over 5-10 microseconds or so. So you can't really delay execution for any significant amount of time, like a page...

Shouldn’t need the FC lines. I don’t think anything in the 68000 Mac chipsets uses ‘em. Are you sure the issue isn’t that the Mac uses exact timing for many routines? Does the PiStorm emulator run in the ARM CPU’s user or supervisor mode? If it’s a user app then it can be preempted any time and...