HP-48G clock mystery

[Kiwi]

In your case, port 1 (128KB) has been merged with the built-in RAM (128KB), which gives you 256KB of RAM. You can create port 1 again with the FREE1 command.
On the hardware side, they probably replaced the 32KB built-in RAM with a 128KB module, added a 128KB RAM module to create port 1 and a 512KB module for port 2 -> 5.