Cache is King – Enable Yours

Quadra 660AV

A Veritable Screamer – a 25 MHz 68040-based Quadra 660AV

Twenty years ago, I had a Quadra “pizza box” style Mac like the one in this picture on my desk at work as my main computer. I don’t remember it as being particularly slow, but our idea of “fast” in those days was quite different from what it is now. Fast forward to 2013. I picked up a Quadra 660AV on eBay early this year, fully restored it and loaded it with a collection of my favorite software from the era. It didn’t seem particularly fast, but I wasn’t expecting it to be (after all, how fast can 25 MHz be?), and the 90 seconds or longer it took to boot was just the way it was.

A few months ago, I picked up another Quadra 660AV on eBay, this time as a source of incremental parts for my existing 660AV. I planned to cannibalize it for the RAM and the hard drive, both of which were significantly larger than the complement that came with my original 660AV. To be sure all was well of course, I installed a new PRAM battery and fired it up. I was amazed at how fast it was! It booted in about 30s, vs. the 90s or so for my original 660AV, and both machines were running the same OS – Mac OS 7.5.3! How could this be?

After some poking around, I discovered the answer – a heretofore unknown to me (or forgotten in the mists of time) control panel called “Cache Switch”. It was loaded and enabled on the newer 660AV – it was not even present on the older one. The purpose of this control panel was to enable or disable the 68040’s onboard cache, and the difference in speed was entirely due to caches being enabled on one and not on the other. Cache makes the world go round! 🙂

So, if you haven’t already done so, make sure your 68040 based Mac has this important control panel installed and enabled. You’ll like the results!

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