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When the machine is off, what’s the resistance between /WE (pin 27) and 5V, and between /WE and GND? If /WE is stuck low the contents of the SRAM will likely get scrambled, as it’ll latch new data when it shouldn’t. The Serial ASIC should only drive /WE low when it wants to write data. If /WE...

Whoa! Mind sharing where you found it? Pricey, but still very interesting!

I’ll second 7.1.x - I’m much happier with my Duo 230 running 7.1 than when I had 7.5.5 on there (even with 12MB of RAM).

Looks like a great option, thanks for sharing!

I am too. If the -12V were close and that was the only thing that was off, I might chance it. My recollection is that the -12V isn’t used for much (serial ports I think, don’t remember what else). But it’s not close - it’s off by 20x (1A vs 0.05A). A bigger concern is the 5V rail. That’s used...

That’s not too surprising. ADB is a shared bus, so as long as the electrical connection between the mouse, through the keyboard, and to the computer is OK the mouse should work even if the keyboard doesn’t. Similarly, the soft-power button doesn’t go through the keyboard controller, it’s just a...

Try pushing the power button on the back of the machine, rather than the one above the keyboard. Try it a couple of times if it doesn’t start up after the first time. The power button above the keyboard is a “soft” power button that goes to the Power Manager, so it only works if the Power...

Wholeheartedly agree - the risk is relatively low (especially given the use case), and the package size difference is definitely a real potential issue. If you’re doing a new design (especially for a design that’s going to experience harsh mechanical or electrical conditions, or that has high...

And along those lines, it’s generally recommended to derate the voltage rating tantalums by ~50% - for example, use a 25V tantalum on a 12V power rail, not a 16V (which would often be sufficient if you were using electrolytics or another capacitor type). Over voltage surges are another thing...

Y1 is the crystal for the real time clock (RTC). The Bomarc schematic says it’s 30 kHz, but no other details are shown. I’d probably recommend leaving it unless you’re seeing issues with the RTC (not keeping time/date, time running fast/slow, etc). If you do replace it, I’d recommend trying to...

I’ve seen newer versions of macOS / Disk Utility refuse to burn Classic Mac CDs with a similar error (don’t recall the code at the moment). I think it’s trying to be too smart, and refusing to burn a disc with a file system it doesn’t recognize (since HFS support was removed some time back). I’m...

My (flimsy) recollection is that modems used the straight through cables, consistent with the (annoying in my opinion) DTE (computer) vs. DCE (peripheral) designations. Printers and many other peripherals used crossover cables. Point-to-point LocalTalk between two Macs also can use a crossover...

Huh, good to know!

My Centris 650 happily drives a multiscan monitor with one of the minimal, switchless adapters.

If the password is the only issue, you should be able to boot from a supported install CD/DVD and reset the password. My recollection is that it’s under the Utilities menu (or something like that) along with Disk Utility and some other tools.

4-pin Mini DIN https://www.mouser.com/c/connectors/circular-connectors/circular-din-connectors/?number%20of%20contacts=4%20Contact&standard=Mini%20DIN

Both look great (awesome pixel art!), but I agree, the 2nd version matches the style of the title screen better.

A pull-up resistor is connected between a signal and the power rail (say +5V), so that the signal is “pulled up” to a logic 1 if it’s not driven by an active driver, while a pull-down resistor is connected between a signal and Ground so that the signal is “pulled down” to a logic 0 when undriven...

@MrPogue The problem is that System Enablers contain both Resource and Data forks (kind of a two-part file), and the Resource forks get lost if you don’t package them into a format safe for transmission across the Internet / across other systems (only Macs are natively aware of Resource forks)...

Thanks! I think I’d seen that at one point in time, and then promptly forgot.