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Do the X500/X600 and related clones use/need -5V on the power supply? According to these two articles posted (but no longer available) on XLR8yourmac.com the answer is no. And given the readership at the time of publication, I assume they would have been corrected by several readers if they...

Term limits are probably impractical for this kind of community organization. For example, if my local rocketry club had term limits there would probably be some years where they couldn't fill out the officer list. People who have time and inclination to devote attention come and go, but I...

Surface Mount X500/X600 CPU Socket AMP 145064-1 Quest also has this in stock: https://www.questcomp.com/part/4/145064-1/16800700 It's been bugging me that we have the through hole parts available, but not the surface mount, and I know some Apple boards used the surface mount. Seems like...

I noticed that on some G3-L2 slot upgrades I have. They must have shopped long and hard to find screws that crappy.... It's kind of like this steak I had at a fancy restaurant in Paris back in '87. They must have labored long hours with great skill to create a sauce that exact shade of...

Demonstration that Beige G3 Personality Slot and X100 PDS Slot are Same: Two photos because I wasn't sure whether with flash and reflection was better or worse than without flash, so dimmer, but no reflections. I should qualify that both the slots use the same connector. They are not...

I keep a supply of modeling clay handy. If there are other components very close to where I'm going to use hot air, I make liitle clay snakes and cover the nearby components. This is mainly to avoid blowing away SM resistors and caps. The first time I used a heat gun on a motherboard to...

Could also be overheating, although that's less likely with a PPC750 than it was with the PPC601. Still, it might be worth checking the heat sink compound.

And in the fine tradition of only finding the answer after one has bothered other folks with the question, I found this datasheet at a vendor who has the SYMBIOS 53C80 available. NCR semi was spun off into SYMBIOS, which was bought by LSI Logic.... None of which are the same as teh...

This is related to my earlier thread, https://tinkerdifferent.com/threads/53c80-experiment.272/ Logic, in their datasheet claims that their 53C80 has better performance: So I actually looked at the pinouts in the Logic datasheet (datasheet attached in above linked thread). And the pinouts...

The term "SCSI voodoo". SCSI works if it's configured properly. If it worked and it stops, it was probably configured wrong and one was lucky it worked as long as it did.

Good luck. Back in 1998 I spent two weeks in the attic during the holidays stringing a half mile of cat 5 and coax cable through the house and dropping it down inside the walls. But these days, my main thought when I consider attic work are the immortal words of the character Roger...

The datasheet for the Logic 53C80 claims Is this a big deal, or just the normal improvement one gets by switching from NMOS to CMOS (5380 vs. 5C80)? It seems like it would be interesting to do before/after SCSI performance comparisons on a Mac II family machine. Thoroughly benchmark the...

So I was pondering the EDO vs. FPM scheme with /OE. And it occurred to me, why not apply that at the Motherboard of the 7200 instead of on just a few DIMMs? But then I remembered that there are multiple /CAS lines to the DIMM. I need to check the pinout for 168 pin DIMMs again, but I'm about...

@Zane Kaminski Thank you for the detailed explanation. I always appreciate the effort you put into education. I also really appreciated the explanation of bus timing for caches on the IIci that you posted a while back but I think that was lost in the great M68kmla fire of '21... I had...

So I've always wondered this and it occurs to me that the folks here might know.... Is the voltage regulator module used in the Beige G3 specific to the Beige G3, or was that a "generic" type of module found in other computers of that age? I'm referring to the plug-in board, not the individual...

I've been answering this question the same way for the last 20 years... The docking card for the Outbound Laptop Model 125. It installs in a Mac Plus or Mac SE and displaces the ROMs. When the Outbound is docked, it can use the desktop machine's screen and ports, supposedly. The host...

Ah, good to know. I haven't done anything with my problem Beige G3, but these anecdotes all support the liklihood that the problem is age/cap related.

The thing is, I'm not sure the memory chips they used actually were 5V tolerant on the IOs. It makes me wonder about what levels the X500 and X600 are actually using. Or the memory maker could have just been crossing their fingers that the memory chips wouldn't blow out before they closed up...

@Zane Kaminski So, I was looking at some of the level shifter chips. And they appear to convert 5V+ to Vcc (3.3V in this case), but in the other direction, the 3.3V outputs just go out as 3.3V to the 5V side. I'm guessing it doesn't matter because 3.3V is still high enough to register as a...

I've seen DIMMs for the X500/X600 built with 3.3V memory and there's no (additional) buffers. Just a 3.3V voltage regulator for the supply pins. I've been meaning to track some of those down and take a closer look. There was some memory from Micron which ran on 3.3V but had 5V tolerant...