8086 has 16-bit registers and 16-bit near pointers but there are also 32-bit far pointers using the segment register. PDP-11, where calloc most likely originat

8086 has 16-bit registers and 16-bit near pointers but there are also 32-bit far pointers using the segment register. PDP-11, where calloc most likely originated, had 16-bit integers and 16-bit pointers. Apparently, later PDP-11s could be split into 64k of code space and 64k of data space (like the Harvard architecture) but that would still use 16-bit pointers.