dougg3's latest activity

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    Interesting! It appears that the DCB structure also allows just setting it to an arbitrary number, according to Microsoft's docs. For...
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    dougg3 replied to the thread LC520 Overclock.
    Happy to help, it's a fun little puzzle. Here's a little mini deep dive further into it. I thought about it some more, and I think I...
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    dougg3 replied to the thread LC520 Overclock.
    My assessment is that R80 only matters if you are using a ROM SIMM. It shouldn't matter for any kind of overclocking or conversion from...
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    dougg3 replied to the thread LC520 Overclock.
    Yep, this is definitely the same circuit as the CC. I just beeped it out as best as I could on my 820-0368-A board from a caddy-loading...
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    dougg3 replied to the thread LC520 Overclock.
    That pin (pin 2) on the ROM SIMM socket is VPP, which is 12V power for allowing EEPROM chips of the era to be reprogrammed in-system...
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    I'm glad you got something working, @JDW! I know I said I wouldn't derail the thread, but just wanted to add one more thing after your...
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    Uh oh! Unfortunately I don't have an actual machine running High Sierra to test against, but I can confirm that in my High Sierra VM it...
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    dougg3 replied to the thread Macintosh performa 475 simm slots.
    It's for a ROM SIMM that could override the soldered-on ROM chips. Most 475 boards I've seen don't have that socket populated; you might...
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    For what it's worth, on the ADB side, bbraun discovered back in the day that the TechStep sends a special ADB command on machines with...