When HP created the HP-28C, it brought the very powerful RPL system to hand held computing. RPL provided sophisticated features like symbolic math, named variables, structured programming and many other capabilities.

However, three features of HP’s earlier top calculator, the HP-41C, were lost – expansion ports, a completely hand-optimized form factor and a fully reconfigurable keyboard. As the model number suggests, the HP-48SX combined the general expansibility, flexibility and form factor of the HP-41C with the advanced math and programing features of the HP-28C/S and added new features of its own.

To understand the HP-48S/SX, the reader should first visit the RPL page. Many of the HP-48’s functions are described there. The HP-48 also included almost all HP-28C/S features which are not repeated here.