Recent content by David Cook

That's cool. I wonder whether other Apple people were jealous of the "In Appreciation Of" plaques and so they made these.

Good programming practice is to check the validity of parameters passed into a function and to return an appropriate error. Over the many years, I've seen different ways of writing these checks. Here, I present four common styles and how it affects performance. Below is a pretty common style...

CR-45S. So, it's loud. 😞

That occurred to me as well. Even if Apple announced discontinuation for consumers, I imagine they would fulfill contracts that went through a lengthy bidding/review process. This would also explain why someone would be choosing a IIx over a IIci in that time period (because they actually...

I saw this really crisp-looking Macintosh IIx on eBay. It has the least yellowing of any case from that era that I have ever seen. (Difficult to tell in a photo with so much wood nearby) I already have plenty of IIx computers, but the serial number on this one intrigued me. It follows the...

Very interesting. Any chance you could take a photo?

On other forums @techknight has said: "What I need you to do now, is check the voltage at the Hybrid, on the pin literally behind the NMI button. it goes into that Op Amp sitting below. It should hover around 2.2 to 2.5VDC. if it falls to 0, or latches at 5V, the system will NOT stay on. If...

Yes. I believe there is an analog voltage provided to the PMGR that represents some fraction of the battery voltage. This allows the PMGR to know when the Portable is plugged into an outlet and to be able to measure battery discharge levels. I believe this also allows the PMGR to soft shutdown...

Last night I went through the Macintosh ROM source code to see if there were bug fixes related to this. While there are plenty of fixes related to inverted text, I didn't find an exact match. In any case, the patches were applied before System 6.0.8. What I did discover was that Apple routinely...

Have you tried running MacTest Pro? It has tests for the video card as well as the computer itself. I usually click the Deselect All button followed by checking the video card, logic board, and ram tests.

This is crazy. Same computer, disk, memory size, video card, slot D, monitor adapter, and monitor. Different results The only known difference is in your parameter RAM. You have a couple of bits set in byte 11 and somehow you've got 32-bit memory set on a 32-bit dirty computer. I assume...

Attached is a disk image I used on a Macintosh IIx with the same ROM and the same Apple Display Card 8*24 (with the same card ROM as you have pictured in your first set of pictures). I do not get any garbled text.

This is unlikely to be useful information to anyone. However, in the event someone is trying to get around an incompatibility with the Apple 8*24 GC graphics card, this may provide clues. Running System 7.1 on a Macintosh IIci, with 32-bit addressing, correctly named 8*24 GC control panel...

Awesome!

@campbellashe Do you have a M5126 backlit Portable? I think you'll want to add a 7MB jumper option, as that model has an address conflict that prevents 1 MB + 8 MB.