2MB 30-pin SIMMs?

I came across a set of unusual SIMMs in my box of memory. Looking up the chip part numbers shows them to be 2MB per stick, which I never knew existed - I always thought 30-pin SIMMs only came in 256K, 1MB, and 4MB.

However there's also a small PAL chip too. At first I thought it was a fake-parity generator, but it's not connected to the parity pins.

So I'm guessing they're specially made to fit something specific, as they weren't recognised at all by the 386 motherboard I tried them in.

Any ideas?

Perhaps it's Macintosh "composite" SIMM modules?

These modules contains special logic that fools the memory controller in some of the Macintoshes. This special logic may be in the PAL chip you describe.

As far as I know 30 pin SIMMs came in 256K, 1MB, 2MB, 4MB, 8MB and 16MB varieties. 2MB and 8MB being uncommon.

I would bet those 2MB were for old Mac II machines (II, IIx mostly) to get the max RAM for OS 6.x (8MB) without the use of later RAM tricks. A IIx needed composite SIMMs over 1MB.

How many actual memory chips are on these sticks?

4x Siemens HYB514400 (1Meg x 4)
1x PAL

Yup, they are strange, but, as was mentioned, they could well be for an early Mac or, possibly, a printer of some sort, like a LaserJet.