Later, it became possible to upgrade the Pilot 1000 or 5000's internals to up to 1 MB of internal RAM. This was done with the purchase of an upgrade module sold by Palm, and the replacement of some internal hardware components. Originally, it was conceived that all Palm PDAs were to be hardware-upgradable to an extent, but ultimately, this capability gave way to external memory slots and firmware-upgradable flash memory after the Palm III series.