PCMCIA is a standard card connector interface used by keyboards,modules, laptop computers,etc. You need to find out what size memory is required for an M1 didyou say? There is a great range of capacities of PCMCIA cards, from 16K to the megs and they're priced accordingly. If you have a store nearby such as Computer Renaissance they're likely to have some used ones.
To your question: you need RAM if you want to write/save anything. These cards will likely be static(SRAM) which requires a button battery. Go to www.pretec.com
to see a range of new cards at reasonable cost.mn