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It's a tach output attached to a hall effect sensor, it has no control influence. You'd need a 4-wire fan to get the low voltage PWM speed control. Or you could add a mosfet inline with the input power to turn it off and on. Probably not worth it when you can just get a Noctua that has enough...

For the next iteration with pass-through support, do you think you can put in a switch or jumper to be able to use it as an analog board & CRT tester with the rp2040 generating test patterns?

acrobat.adobe.com. Sure, you have to pay the Great Satan Adobe, but it exists. The Acrobat desktop app does it too, probably with easier fine tuning. Those new document scanners that have popped up on a few channels look to be in the same ballpark of maturity. It might also be handy for those...

I finally got the code up on GitHub (https://github.com/crackmonkey/macvid). Fine tuning the timing was giving me a headache for a while, I think because the "Classic II Developer Note" timing diagram said that a scanline should be 49.93us but the blog post with oscilloscope screenshots I was...

2TB on an SE/30? Impressive ;)

I tweaked the full speed PIO program a little to make it assemble in circuitpython's assembler and to use delay cycles instead of repeated nops. It seems to be working. I also fired up a second State Machine to generate an HSYNC signal for it to respond to. I have python feeding this 177, for...

The word doesn't get pushed into the FIFO until it's "full", where "full" can be set from 1 to 32 bits. I was figuring on leaving it at 32-bits so a scanline would be 64 bytes, aka 16 words, pushed to the ARM core. A slight PLL tweak should provide an overclock to 125.33333 (off the shelf Pi...

It shouldn't change in operation so once the timing is figured out it should be fine. Someone with a faster scope could try changing the "side 1" on the next to last line to "side 0" it'll change the output to do a fast square wave at 2x pixel clock with it going high when sampling and see how...

Hmm, my PIO program runs at twice the pixel clock in order to have time to do the necessary looping logic so it might actually be sampling in the middle of the pixel already. If not, it would be trivial to add a 1 cycle (1/2 pixel) delay to before starting the capture loop.

I've got the basic scanline timings working on a PIO. H-Blank: Right now the program is just NOP-ing instead of reading a pin because I don't have the reading part built out and Mu hates it when I print tons of numbers. I'm driving a side pin high while in the reading pixels loop and low...

I don't think this site is specifically for vintage stuff, as long as you're Tinkering with it it seems like fair game

The PIO units do their own IO on their own clock, so there's no need to use the SPI engine. It can delay X pixel clocks after detecting the end of HSYNC and then start reading on the next cycle. By default GPIO reads will be queued for the main CPU in 32-bit words in a 4 or 8 word deep FIFO and...

The PIOs do fractional clock dividing. A quick test in circuitpython say `real frequency 15663240` when I request 15.6672MHz, that might be enough to hold for 1 scanline. My Salae logic analyzer only does 12MS/s so I guess it's not fast enough to capture individual pixels but when running a...

The Pi Pico's PIO units should be able to be clocked to sync up to with the Mac and easily get accurate pixel samples without having to oversample. Some math would be involved to figure out how to divide the system clock (48MHz) down to the pixel clock and setting the PIO unit to run at that...

you shouldn't need the power supply from the enclosure, the BlueSCSI should get all the power it needs from the termination power provided by the computer.

It probably isn't that smart. I'd bet it's just presenting the whole SD card as a disk with a simple 1-to-1 sector mapping. You can probably use Balena Etcher or something similar to write a pre-made image to the drive. A modern Mac would probably be able to mount the SD card and add files once...

That second one is a passive SCSI adapter, so no help there, and it would be way too big to fit into a powerbook. The first one is for the very-rare outside of pre-touch screen iPods 1.8" drives. They probably had to split the power over more pins than the 44-pin laptop standard because those...

is it wrong that I want to hack a bridge to these forums?

...a couple more pennies on the floor... I suspect that the detailed categorization will help down the road as a long term information repository rather than just the "what's happening today" chatter. I thought that part of the idea behind TinkerDifferent was to grow a repository of knowledge...

an external Active terminator instead of the passive resister nets on the *SCSI emulators would probably work better