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-bITword 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-bIToperation 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)
