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Typo regarding pin 6 on the table, IMHO. When the computer first powers up, all the chips will be held in reset (frozen state) by the Sony sound chips by outputting a low (0V) on pin 5. In schematics, the little bar above the word "reset" or the little circle next to the pin indicates the...

Actually, that looks good. The computer is in reset when when pin 5 of each of those chips is low (0V). The computer runs when pin 5 of each of those chips is high (5V). So, that looks to be working (don't worry about the voltage of the reset button -- it's correct and functioning.)

You should still check S1 (to make sure it isn't shorted). However, given the resistors (100/(100+27))*5V = 3.94V, the voltage when pressed should be about 3.9V volts. What are you getting for pin 5 of UB11 and pin 5 of UB10 when the button is pressed and released?

With power off, check the continuity of S1 when pressed and not pressed. This switch often fails due to capacitor juice. I've replaced several.

After you get the message, if you push the rear button, does it power off? If it does, then there's only a couple of possible issues. Most likely, check continuity between UE9 pin 60 and UB13 pin 1. Other people have had that fail at a via due to capacitor juice.

Here is what I’ve learned. Unless noted otherwise, all of this information is based on System 6.0.0 and Inside Macintosh Operating System Utilities. It may have changed in later systems, particularly when PowerPC came along. LongDate2Secs (aka LongDateToSeconds) and LongSecs2Date (aka...

Bummer. Why didn't they just use a 64-bit integer at that point. It is slightly understandable when the 128K Mac came out. But, by the time of the Newton, they didn't need to save four bytes.

Yes, you're doing the right things. Here is what the traces look like underneath the chips. Turn off power and check that each trace connecting to each pin of UB13 and UD13 have continuity. For example, even though it looks good, my board had a tiny break where the red arrow is. I'll bet you'll...

Even better: Do you recognize the board being manufactured?!

Thank you. I'm trying to lock down the definitive System release that includes those functions, as well as which structure fields are actually output-only (PM for example). The more I think about it, the more I believe any documentation will be untrustworthy and I just need to reverse engineer...

I've been researching the Apple system routines that use LongDateTime as part of a potential solution to the 2040 problem. Because it is first documented in Inside Macintosh Vol VI, I assumed that those routines first appeared in System 7. But, on closer inspection and with some testing, those...

Each time I let an eBay auction get beyond me (I set a mental price point and don't go over it), I think to myself "Someone else must really want that Mac and it is going to make them really happy." I don't feel like I'm competing against the rich, I feel I am competing against decay. I suspect...

Just watched it. Besides the usual precise technical information, my favorite thing about your videos is the production quality. Nice ending -- Merry Christmas to you!

On @JDW ’s thread regarding the Macintosh Portable (https://tinkerdifferent.com/threads/powerbook-100-170-owners.4811/), he posted a link to a technical note...

PowerBook 100: 25 mm PowerBook 170: 30 mm

I just did a quick test. The original ADB mouse uses 70 mA (64.8 idle). The low-power ADB mouse uses 4.8 mA (4.65 idle). The low-power small black ball ADB mouse uses 5 mA (1.75 idle). The low-power small gray ball ADB mouse uses 4.8 mA (1.57 idle). The Apple Desktop Mouse II are similar to...

Only normal, I'm afraid. I'm interested in learning if the long connector has something special in it.

Oh, and at least two more variations exist: non-low power small light-weight black ball (on the left side of the image below) unusual ball retainer and skid (image below)

Yes. Apple ADB mice in my pile (not counting Apple Desktop Bus Mouse II or later) (5) large heavy gray ball (2) low-power large heavy gray ball (1) low-power small middle-weight gray ball (3) low-power small light-weight black ball If you add in the Portable with a 1" inch connector, then there...

I suspect they learned a lot about power usage when designing the portable. (The Apple IIc was always plugged in, correct?) I'll guess that the order went: 1. Original mouse 2. Portable mouse 3. Hey we figured out how to make low power mice and will need some for our PowerBooks -- let's just...