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Those PBs do not all use the same design of memory-expansion card. The ringing of the changes has been covered before in these forums, eg:
viewtopic.php?f=4&t=9908
In brief, 180c and 165c (only) use a cousin-card of 10MB (max.) to reach the 14MB RAM-ceiling. The cousin-card attaches at the left edge of the daughter-board, and thus it lies at 90° to the usual expansion card's orientation. The daughter-board of most, but not all, other PB1nn models, including the 160/180, is different in that its socket for the expansion-card is at the rear edge nigh the video-out (to the display) connector. Different therefore is the 10-MB (max.) memory-expansion card also.
de
viewtopic.php?f=4&t=9908
In brief, 180c and 165c (only) use a cousin-card of 10MB (max.) to reach the 14MB RAM-ceiling. The cousin-card attaches at the left edge of the daughter-board, and thus it lies at 90° to the usual expansion card's orientation. The daughter-board of most, but not all, other PB1nn models, including the 160/180, is different in that its socket for the expansion-card is at the rear edge nigh the video-out (to the display) connector. Different therefore is the 10-MB (max.) memory-expansion card also.
de