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@JDW You misunderstand me - I'm saying those instructions are incorrect, or there is an error in the PCB design. By following those instructions you DISCONNECT the socket from the FPU. But... I don't just mean put it back, because then you would have two clocks at once. I was asking about...

@JDW... Just a thought... but I've worked out part of what is going on. You removed the blob of solder? So if you break the connection between pin 8 (Output) on the clock, and the FPU itself... how is the FPU clock meant to see the signal from your 33MHz clock? I think there has been a...

More than that, it would require a redesign of the card - this is a fairly simple card and its timings aren't disconnected from the SE's primary bus speed. I think it uses the motherboard 15.67MHz clock signal. The 68882 runs completely asynchronously and happily works with whatever clock you...

The FPU runs asynchronously though? Plus the many clock cycles it takes to do floating point, even with an FPU, means that memory shouldn't be a limit within reason. Also, this behavior doesn't match my experience with basically the same card, so it is either a clone issue, or a setup issue I...

I didn't see this in my first read through. This doesn't match my experience with my version of the card. For Norton's quickdraw benchmarks, the accelerated SE scored... 62% faster than a stock SE. Again, I'd suggest installing GemStart and re-running benchmarks. Edit - Here is a summary of...

Further to my previous post, I had a look in my phone for photos of old benchmarks I've run. In the following "Upgraded Macintosh SE" is an SE with the Total Systems Mercury fitted - as mentioned, this is electrically identical to the card your card is a clone of. Different brands, same card. I...

There is something strange going on here certainly. Normally, in part because of the asynchronous operation, FPU performance scales fairly linearly with clock speed. So, these cards are electrically identical to the Total Systems Mercury - I have one, but not set up. I could compare your...

Thought I'd make it more retro computer specific. Here's one for the vintage mac crowd : Edit : After modifying the software a little so I could change the sample rate and x axis resolution, I ran the light and temperature sensor for a bit over an hour over sunset. The temperature probe was...

I've seen similar ones, but I don't think I've used one like that. What an absolutely weird way of setting the voltage! Nice to have low voltage AC.

I'm trying to remember what we had. I couldn't find a picture. The physics labs had... like, boxes with a recessed face and a big dial in the middle, like a 2" knob with a 3" flange (giggles). Same banana jacks. In the tech department they had much newer stuff and they had variable DC power...

Updatier - Added some details about the Contact Controller Plus to the same page above, which seems to use the same serial commands. Had to build little adapter for the power connector as it used a 5pin DIN connector.

They're old 68020s and 68881s. The XC means they're pre-validation, and the date codes look to be (late) 1985.

Update - Motors are at least in part controlled by command 0x47.

Made some good progress last night. I plugged in a Data Harvest FlowGo I'd picked up a while back. It didn't have any software with it and I hadn't done anything with it. I enjoy playing with old educational interface boxes - it was a big thing here in the UK in the 80s and 90s for teaching...

Yeah, that sounds like you're hitting your head on the speed limits due to the MC88920. It seems to be the first limit you bump your head on if you're not limited by the CPU.

Well now, looking at the source? That's cheating :ROFLMAO:

They could probably just use 74xx165s. All they're doing is checking the status of a matrix. I'd assume they're not planning on running every key to a pin.

This is probably of interest : https://github.com/elliotnunn/supermario/blob/master/base/SuperMarioProj.1994-02-09/OS/CudaMgr.a https://github.com/elliotnunn/supermario/blob/master/base/SuperMarioProj.1994-02-09/OS/EgretMgr.a Edit : I wasn't able to see an appropriate trap, even in the C...

The code here : https://github.com/cheesestraws/Force32/blob/main/xpram.c ... uses a trap to read / write XPRAM. I assume there is something similar for the general address space of the CUDA chip. Someone with perhaps inside knowledge might know what that trap is, or perhaps it is buried in...

Its connected on the logic board to a VIA by a basic bit bashed serial port from what I understand, so not memory mapped. So you could send any command to it you like by driving the pins on the VIA, which is memory mapped and well understood. What is weird is that there must be a memory dump...