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    PM X500/X600 Power Supply and -5V?

    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...
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    2.5" SCSI Physical Dimensions?

    I'm slowly progressing towards building a SCSI to mSATA adapter that would fit in the SCSI PowerBooks. To properly size/outline the PCB I need to know the dimensions of the SCSI drives used in PowerBooks. Did they all use the same arrangement of mounting screws -- standard on 2.5" SCSI...
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    Beige G3 Locks Up at Welcome to Macintosh Screen?

    I suspect I have a corrupt system and need to do a reinstall, but figured I ask here in case someone else has seen this and has an easier fix. I was experimenting with various hacked PCI cards last night. Install them. Boot the G3. Look at ASP. Shut down. Now, when I boot in OS 9.1 I get...
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    264 MB in PowerMac 7100 Hack

    I'm not about to embark on this hack, but wanted to post the concept while I was thinking about it. The only reason the 7100 is limited to 32MB SIMMs is because it runs the upper address lines for the SIMMs through a chip which "steals" them to create RAS lines to support more SIMM sockets...
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    Pin Matrix for PPC ZIF modules?

    So I've wandered off and come back to the ZIF modules as a reproducible project over the years, but it always boils down to that pin matrix on the bottom of the module. It looks like some kind of odd surface mount to PGA matrix and I haven't managed to turn it up anywhere. I had some evidence...
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    PPC750GX vs. PPC750GL?

    I feel like I've asked this before, but nothing came up in search. Maybe it was lost in the great crash of 2021. Anyway, anyone know if there are or are not issues in replacing the 750GX with the 750GL? The impression I gather from datasheets is that they're software and pin compatible, but...
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    Converting Acard AEC-7722 to AEC-7726

    I'm moving this discussion to Hacks. The beginning is in Trading Post, here: Beginnging of Hacking Following up on my last post in the previous thread: I wasn't going to mess with it again in what little is left of the weekend, but I tried that last experiment. I connected a Flash-less...
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    Radeon 7000 Capacitors

    Are these going to need replacing eventually? What do folks think? They look fine, so far. Also the marking seem a little different than I'm used to. They say '100' NL '16G' NL '572' where "NL" => Newline. I'm guessing 100uF X 16V, but I'm not sure. 100F seems high.
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    Acard 67160M, 67162M; Anyone Have One of These?

    I found some cheap PC versions of these cards. I was wondering if anyone has the Macintosh version. Or more directly, knows how to convert the PC version to the Mac version.
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    Reading an SM Resistor Code 820 vs. 028

    They're so tiny, I guess it's reasonable that the 2 looks the same right-side-up as upside-down, but grrrrr. I should just pull out the ohmmeter, but... Anyone know off hand if 028 would be a valid resistor code? Seems like it would always be 207 and never 028, suggesting that these must...
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    ROM Memory/Address Space in PCI Power Macs?

    In the Hardware Developer Guides for the 68K Macs, Apple published address maps showing where everything was located in address space and how much addressing space was available for each device. This is how the ROMinator builders knew that they could put an 8MB ROM in a Mac II family machine...
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    ACARD Support Gone

    Acard has removed files/support for all their old products except SCSI/IDE bridges from their website. Actually, it looks like the whole company has changed identity. Anyway, if you need or in teh future may need drivers/firmware/utilities/manuals for Acard products, get them from the Wayback...
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    540MB MO in Fujitsu 640MB DynaMO?

    Anyone know if the 540MB 3.5" MO disks work in the Fujitsu 640MB MO drive?
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    SRAM for Portable "on sale" at DigiKey

    Digi-Key has some Cypress 2M X 8, 1M X 16 SRAM for sale at about $5 a chip.  There's a big "No Warranty" label on it.   This is probably a drop-in for TechKnight's design. https://www.digikey.com/product-detail/en/cypress-semiconductor-corp/CY62167G-45ZXI/2015-CY62167G-45ZXI-ND/9771526
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    32 bit vs. 36 bit Cache Chips for PPC750, G3

    I've seen the 36 bit wide cache chips used on a number of PPC upgrade cards.   Does anyone know if the four parity bits are actually being used, or was it just convenient for the manufacturers to buy the X36 chips for some reason?   The pin out is the same, so if one has a board that only needs...
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    Mac IIci with Sonnet 68040 & Radius Precision Color 24X

    Picked up a IIci from Ebay last week.  From the internal picture I was pretty certain there was some sort of 68040 accelerator and a video card.   Very similar to ExplodingLemur's find a couple of weeks ago. I could only see the top edge of the video card, but based on the chip arrangement I...
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    XLR8 Carrier Card Extended Speed Settings

    Apologies if I've posted this before.  I don't think I have.  I ran across this in some of my old documents. The "official" instructions for the XLR8 ZIF Carrier Card omits many possible switch settings in their speed chart.   Here's how to figure out what the other switch settings do.   I...
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    Macintosh IIvx, Detailed Scan/Image?

    I am looking for a detailed (good enough to read chip markings) image of a Mac IIvx motherboard.   Images of the P600 and IIvi will not do, as it is precisely the differences, I want to see. Specifically, I'm interested in the corner/edge of the board where the Cache and Tag RAM chips are...
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    Cache Puzzlement

    The appearance of two Performa 600s, which lack the IIvx's cache have sent me on an exploration of the art of the cache. This is a pretty good reference regarding the basics: https://courses.cs.washington.edu/courses/cse378/09wi/lectures/lec15.pdf Basically, you have two sets of memory, which...
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    Performa 600 Anyone Added the Cache

    I recently received a lot of logic boards and sundry via Ebay, and there are two P600 boards included.   I thought they were IIvx at first, until I discovered that the P600 is just like the IIvx, except for the lack of cache and FPU. So those solder pads are just sitting there, staring at me. ...