SHARP APL was a standalone version of APL offered by I.P. Sharp Associates (IPSA), who had previously offered APL interpretation as a timesharing service. IPSA employed many notable APL designers including Ken Iverson, and SHARP APL was the source of many developments in flat array theory.
SHARP originally supported only real numbers using double (8-byte) precision. Numbers were stored in one of three types:
Boolean, with one bit per value
Integer, with four bytes per value
Floating, with eight bytes per value
SATN-40 describes the addition of complex numbers to SHARP APL.
SHARP APL Technical Notes
Features of SHARP APL were documented in "technical notes" issued by IPSA. These notes are numbered following the scheme "SATN-0". Earlier notes typically had no author listed. A pdf collection of SHARP APL Technical Notes is hosted at jsoftware.com, as are html transcriptions of some notes, linked in the table below.