How much RAM is on this 30-pin SIMM?

Is there a rule of thumb when looking at a 30-pin SIMM to determine its capacity? All my 30-pin machines are compacts, and I don't always have one open, so just plugging them in to find out their size is quite an operation.

I've noticed that some of my 1MB SIMMs have 8 or 9 chips each labeled with some combination of characters which include the number 4100 (like HM514100AS7 or TMS44100DJ). I can't think of any correlation between the number 4100 and 1MB.

I don't have any smaller or larger loose SIMMs to compare with, so I'm not a great source of information.