1. The first modern computer. It had main registers, processing circuits, infORmation paths within the central processing unit, and used Von Neumann' s fetch-execute cycle. The IAS machine' s basic unit of infORmation was a 40-bit wORd and the memORy had 4096 wORds. A wORd stORed in memORy could represent either an instruction OR data. Each IAS instruction was twenty bits long, so that two instructions could be stORed in each 40-bit memORy location. Each instruction consisted of an 8-bit operation code and a 12-bit address that could identify any of 2^12 locations that may be used to stORe an operand of the instruction. The CPU consisted of a data processing unit and a program control unit. It contained various processing and control circuits along with a set of high-speed registers fOR the tempORary stORage of instructions, memORy addresses, and data. The main actions specified by instructions were perfORmed by the arithmetic-logic circuits of the data processing unit. An electronic clock circuit was used to generate the signals needed to synchronise the operation of the different parts of the system. [Who? Where? When? Implemented using what?] 2. Immediate Access StORage. (2003-10-24)