HP42S=Hp17Bii but different ROM¿


That's my question


Yes, you are 100% correct. Circuit board, passive components, case, keyboard sheets, everything but the keytops and ROM. You can also add the 27S so that:

17B = 17Bii = 27S = 42S

The only very fine detail of difference is that when the 17Bii moved with production to Indonesia, they changed the molded keys to printed keys. AFAIK, the 42S and 27S all have the nicer molded keys.

So the $64,000 question: Why did they drop the 42S in 1995 and continue to produce the 17Bii until 2002? IMO, they did not what to harm 48 sales.


... the 17BII has more ROM. Or, in other words, the 17BII has an additional ROM chip, which features the language-specific messages.



Only the international version units. The standard ABA english units do not have the addition rom chip.


HP-42S is probably intended to have the second ROM, too, starting at the address #20000. That's why the misterious XFCN instruction exists:

128EB   =xXFCN
128EB 1F00002 D1=(5) #20000
128F2 143 A=DAT1 A
128F5 34F3CA5 LC(5) #5AC3F
128FC 8A6 ?A#C A
128FF 90 GOYES L_12908
12901 8F50002 GOSBVL #20005
12908 L_12908
12908 8C8FA3 GOLONG #16402

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