HP-48S vs. 48G vs. 42S

[Ron Ross]

The Hp 42s is simply smaller and a pocket calculator with 8 K of RAM. The Hp 48s and Hp 48G are both superior in functions and features (although, for shear number crunching of complex numbers and complex matrices, the Hp 42s can actually be configured to be more efficient, from my experience). If you have an Hp 28s, the next calculator to replace it is the Hp 48s.
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The Hp 48s was released to provide a student edition of the Hp 48sx. It came with 256K of ROM and 32 K of RAM. Therefore, it has lots of built in math functions and features for its time. The Hp 48G and GX came about 2 years later. The Hp 48G came with 512K ROM and still only 32 K of RAM plus Hp doubled the clock speed ie the calc was about 150% faster. However, the extra ROM was basically a physics pack installed ie the older Hp 48sx ROM card for physics (minus the chemistry).
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The superior black screen you mention may not be available for the Hp 48G version or if it is, it is rare. I believe Hp provided the black screen for the later Hp 48G+ (which directly replaced the Hp 48G) and the later GX versions. The Hp 48G+ is basically an Hp 48G with 128K RAM in place of the 32K RAM and usually the Black screen.
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My personal feeling is that most Hp 42s's are way overvalued, especially if they are beat to H377! Calculators in that condition can fail at any time (heck, any 25 year old calculator can fail, even in pristine condition). It lacks many of the features you might be used to with an Hp 28s, ie no units conversions, RPN 4 stack (not unlimited RPL), one fourth of the RAM and a keyboard that IS NOT optimized for key coding.
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The Hp 48s and Hp 48G calculators are an excellent value for an Hp user. You can get a far superior calculator in usually great shape for about $50 vs a new Hp 35s that is actually oversized and may or may not last 5 years or so. In fact, I always keep an Hp 48G in my desk for the units conversions, often just as fast as looking up an online conversion tool or for back of envelope number crunching. I could use any of the high end models, but I kind of prefer the older look and feel of an Hp 48G (The Hp 48s does have a nicer look, but is about 50% slower and it feels slower, even slower than an Hp 28s too, probably because of the larger screen for the cpu to drive).
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I am of the belief that Hp purposefully makes their new low end Hp 35s with inferior quality (or provides $50 quality 5 year life, when they could provide $60 quality 10 year life) on purpose to perpetuate continued calculator sales. Hp learned its lesson with the Voyager and Pioneer lines. Build it too good and you will never see THAT customer again!!!
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