HI.
In terms of compatibility, there are only two main differences between the A and B models.
The 82240A has a single character set, while the 82240B allows you to choose between ROMAN 8 and ECMA 94. Both character sets repeat the same characters in the lower range (0 to 127, or 0x00h to 0x7F), while the upper range (128 to 255, or 0x80 to 0xFF) differs in almost all characters.
The second difference is that the HP82240B leaves an extra blank ´dot line' in the top of all characters, which allows a better text reading while keeping graphics printing with no blanks between printed lines.
If a calculator can operate the HP82240A it can also operate the HP82240B. The HP48 series offers an operation named 'OLDPRT' which remaps its printing output. You see, the printer itself is not 'changed', the calculator itself generates the correct codes so what you want to print will actually be printed in each printer model. The main issue is that some characters available in the later calculators do not have matches in the HP82240A, so some characters will not be printed as expected. Some calculators, like the HP42S, print correctly with the HP82240A but they can also use the HP82240B after sending the correct 'escape sequence' to select ROMAN 8 character set.
I guess that more details can be found in their manuals.
Cheers.
Luiz (Brazil)
Edited: 14 Apr 2012, 8:28 p.m.