Retrotronik RAM card for HP 48GX

[Joe Horn]

(07-01-2021 10:01 PM)Eric Rechlin Wrote:  4 MB cards mostly function but have a problem with the last port, so they generally aren't recommended.

Does anybody remember (or have a link to) what the Port 33 Bug was, exactly? I vaguely remember that Port 33 will actually exist (if you have a 4 MB card in slot 2 of a 48 GX), but that it misbehaves in some nasty way. Any info in that regard would be helpful. Thanks in advance! Related question: Is there any way of write-protecting ONLY Port 33, so as to avoid getting bitten by the Port 33 Bug?