Level 2 Cache for the 68040

A Level 2 (L2) cache was a popular way to boost performance on faster 68030-based Macs, including the Mac IIci, Mac IIvx, and Mac IIfx. But none of the 68040-based Macs shipped with an L2 cache, although most were capable of using one. The L2 cache is automatically accessed by the 68040 series processor, whether LC040 or full 040 – no additional software is required. 

When Motorola designed the 68040 CPU, it was designed to look for the L2 cache when the power came on, so there usually isn’t a control panel or software addition to use the L2 cache. This is especially true with the “no slot” solutions, where the L2 cache consists of a small daughter card that plugs into the processor socket, and then the existing processor plugs into the daughter card. A further variation of this was the QuadDoubler 128k, which had both 128 KB of L2 cache and a double-speed CPU.

Given this, the only limitation to getting an L2 cache into your machine is how the acreage on the motherboard is divided. Since each design may move or relocate the 68040 socket to a different spot on the motherboard, making a no-slot cache solution may mean making sure that the cache card does not hit the case wall or block expansion slots. In addition, enough case height must exist so that the card can be installed and the lid still put on the machine.

Because of the various designs of Apple’s 68040 motherboards, it would be necessary to make four different cache cards to fit all of the motherboards available, with a few exceptions. This is an ad hoc list of those that I know exist. Note that Quadra/Centris/Performa is the same thing on this list, even though there may be minor differences between them. In terms of the L2 cache, they take the same kind of card.

* LC575 is the only model that has trouble – I have a supplier that has ad hoc 575 cache cards – please contact me directly if you’re interested in this option.

Please note, I have not found a cache card for either the Quadra 630 or 640. Don’t ask. If I find a supplier that will meet the constraining needs of these two motherboard classes, I will of course announce it on the list.

As well, if the above list does not match your form factor, then I haven’t seen one. The list above is as complete as I am aware of. I don’t know of any other machines but the ones on the list above. There is no need to ask me if your machine is supported if it’s not on the list, because I haven’t found one that works with it, whatever the model.

Scott L. Barber <serker@earthling.net>
Pres/CEO, SERKER Worldwide, Inc.
Providing Hardware/Networking/Telecomm for 13 years

Scott L. Barber first posted this to Quadlist, the listserv for users of 68040-based Macs. It is reprinted with his permission.

Micromac once made a 128K L2 card for many 68040-based Macs.

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