You can use Apple PowerBook memory cards (2MB or 4MB cards) in any of the Macintosh PowerBooks.
However, third party cards designed for the Macintosh PowerBook 140 and 170 are not necessarily compatible with the PowerBook 100 because the 68000 has a 16-bit data path, whereas the 68030 can handle 32 bits. The PowerBook 100 requires additional signal lines on the memory card to do addressing correctly. In addition, the physical form factor may not be the same.
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