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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...

Those chips might be useful in adding the on-board memory back to the PM6500 though.... There was motherboard memory on the 6400, but Apple discarded it for the 6500, but left the pads on the board. I think that 1M X 16 is what's needed for those pads, but I'm not certain.

Clever. I like the concept. Making the Block RAMs of an FPGA into the TAG RAM is a great solution. Gets around the problem that there just doesn't seem to be properly sized tag RAMs available.

Kind of a more general continuation of the WTB 1MB cache for x100 machines thread. So paging @Ron's Computer Videos into the thread too. (First, I should mention that the Power_Macintosh Hardware Developer Note (for X100 machines) says the cache logic is in the HMC chip. So no need to...

Sounds like you've got what you need. Compared to some of the conversions done today, the 2940UW was really pretty easy, but it was also one of the very first that anyone did. I think it predates all or almost all the video card conversions.

I just bought one of those. I saw an article that linked to the seller somewhere. The thing that puzzles me is that the 2.5" connector is 50 pins. Isn't the connector/cable on the 2.5" drive 40 pins? Does the adapter cover the SCSI ID pins and then move that functionality to the...

So you're saying Kai is Dr. Who?

What does the group mind think about trying to recover/republish some of the material that's been lost to time? In particular, I'm wondering if Mike Breedan (sp?) still has the many, many how-to articles that he's pruned from xlr8yourmac.com over the years. Plus the old compatibility...

@Kai Robinson I wrote an article on that about 25 years ago... It has way too much detail on the difficulty of desoldering a PLCC32 Flash chip -- a process that is more or less trivial to us today, but seemed like magic back then. You're best off just skipping down to the summary...