Not particularly unique at all. Handheld graphing calculators typically were not intended for use where hardware floating point was necessary. TI calculators historically used the Z80, no FPU. Earlier HP calculators did use a custom BCD based (not IEEE954) floating point ISA, but these are still slower than just about any processor in the past 30 years doing software floating point. They didn’t have any hardware multiply or divide for one, this is not an FPU in the modern sense people envision. And later on the HP used common ARMv5 based processors with emulation. None of these ARM processors had hardware floating point. Same with later TI calculators that were 68k and then ARM based.
The HP Prime G2 released in 2018 is about the only mainstream device that happens to have hardware FP, and that’s for a device more touted for CAS features. The FPU is more just something that comes for free with the commodity SoC chosen.
> None of these ARM processors had hardware floating point
More importantly, IEEE 754 floating point ISA is not great for calculators - they don’t require the speed a personal computer does, and calculators work hard to hide the fact numbers such as 0.45 can’t be represented as IEEE 754 floats.
The HP Prime G2 released in 2018 is about the only mainstream device that happens to have hardware FP, and that’s for a device more touted for CAS features. The FPU is more just something that comes for free with the commodity SoC chosen.