In both the HP 48S/SX and G/GX series, the Saturn CPU core is integrated as part of a more complex integrated circuit (IC) package. The processor has a 20-bit address bus available to code but due to the presence of the high/low nibble selection bit, only 19 bits are available externally. External logical data fetches are transparently converted to 8-bit physical fetches. The main registers A, B, C, D, along with temp registers R0, R1, R2, R3, and R4 are a full 64-bits wide, but the data registers D0 & D1 are only 20-bit. The HP 48 series' Saturn microprocessor is a hybrid 64-bit / 20-bit CPU hardware-wise but acts like a 4-bit processor in that it presents nibble-based data to programs and uses a nibble-based addressing system. 48GX ASEE: 1993 (special edition labelled '1893 ASEE 1993 Shaping our world - Century II').

Likewise, the hardware and software design of the HP 48 calculators are themselves strongly influenced by other calculators in the HP line, most of all by the HP-18C and the HP-28 series.

The hardware architecture developed for the HP 48 series became the basis for the HP 38G, with a simplified user interface and an infix input method, and the HP 49G with various software enhancements. Note that the similarly named hp 48gII (2004) is not really a member of the series, but rather much more closely related to the hp 49g+. The SX and S models have the same amount of onboard memory. The G+ models have more onboard memory only. In particular, the GX models have more onboard memory than the G models. The models with an X suffix are expandable via special RAM (memory expansion) and ROM (software application) cards. The series include the HP 48S, HP 48SX, HP 48G, HP 48GX, and HP 48G+, the G models being expanded and improved versions of the S models. The HP 48 is a series of graphing calculators using Reverse Polish Notation (RPN) and the RPL programming language, produced by Hewlett-Packard from 1990 until 2003.

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