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By the way, did you say you had a logic probe? It might be worth wiring up some of the address bus on a ROM and seeing if you get the expected request for $0. Plus the correct enable signals. Sorry if you already tried this.

Would it help to fit a 5R or 10R resistor to the end of one of the probes? Perhaps just lift it out of the range so you only beeped for real shorts?

Macs can have such a low resistance that some meters will beep continuity between ground and 5v on a working board. It... can make trouble shooting tricky :ROFLMAO: The first board I repaired I had to get my dad to measure the resistance on his similar machine to check because I couldn't...

I get 16R at the hard disk power connector between Gnd and 5v. That is in line with what I've measured on other Macs in the past. They're very low resistance, not sure if it changes when they power on or what. I guess it is only 315mA. 10R is a bit lower, but I'm not sure what the tolerance...

I'll measure one of mine, just a mo.

I think we have wires crossed, that's what I was saying. I was using it as evidence that code isn't executing because it never goes low from its reset state of high.

I'm pretty sure that the overlay starts high : ...

Just double checked, you should have three jumpers fitted on the board total. W1, which enabled the onboard ROM, and W3 with two jumpers, which are always fitted - they're something to do with disabling some CPU lines that were probably used during debugging at Apple.

Good work, it is that hard bit. Tedious and repetitive. Yeah, that sounds like no code is executing. If I have things the right way about, High is the start state, and it should drop low when code starts executing. Hum, given the above, we already half have an answer, but what I'd probably do...

Lets take a pause and breath in how awesome it is that someone cloned a Rocket before we ask them to do an even more difficult job of redesigning it into something even the original manufacturer didn't make :ROFLMAO:. Also, apparently modern FPGAs often struggle to get the low latency...

That sounds like a bad cable or poor termination. First thing to do is check your termination settings - things sometimes still "work" when set wrong, just you get an increased number of retries meaning slower throughput. If that doesn't help, try a different cable? Issues like this aside, the...

Yeah it was me that first raised it as a solution on 68kmla (I never saw it anywhere before, but I mean, apple engineers knew and someone else might have spotted it if they were familiar with the 88916 and beeped around the chip). My machines were always stable at 33MHz so I hadn't needed to...

Was worth checking :)

What EEPROM part was fitted before you did any modifications? SATA cards use a mixture of 3.3v and 5v EEPROMs depending on the board design, the MX29LV040 is a (nominally) 3.3v part. If your card is feeding it 5v, that might explain why it died.

I've made a couple of tweaks to your drawing, sorry they're not in the same font (and one is a little small!). I hope you don't mind! : I added the main clock because I think it is worth grabbing (I've called it the reference clock, because all other clocks are created from it, but a...

Yeah, that is just Mac OS 8.0 with a custom boot screen. I used to always be editing mine as a kid, and there was commercial software to make it easier. Not that it was hard anyway, you just needed to shove a MacPaint document or file with a pict resource in the system folder with the right name.

:) Good luck

When things are a bit less hectic, could you run some of the Phil's computer Lab benchmarks? I can probably dig out a pre-made image for you if needed (but I think someone already has on Mac Garden - I'll take a look and edit this post). I'm curious how the 5x86 compares to the 100MHz Intel...

The black 6100 :) Just to warn you, I believe they clash with the lid, so people have to do a bit of hacking, plus you need an extension like the one you have in the 650. At least, that's what it says on Jagshouse.

I mean, if you want it to happen fairly quickly, 27 Ohm would motivate them with about 100mA @ 3v. I'd probably use 68 Ohm though for 50mA @ 3V. It will just finish flattening them. You could just put a blue or white LED on them though, that would give you a visual indication (don't use other...