Non-fiction: First Draft of a Report on the EDVAC

Overview
The First Draft of a Report on the EDVAC, circulated by John von Neumann in 1945, set out a clear blueprint for electronic digital computing that crystallized the stored-program concept. Written while EDVAC was being designed at the Moore School and the Institute for Advanced Study, the report summarized technical meetings and collated design ideas into a coherent model for a general-purpose machine. Its accessible, systematic presentation made it widely influential among early computer designers and helped shape the lingua franca of computer architecture.

Core technical proposals
Von Neumann articulated the use of a single, central memory to hold both instructions and data, encoded in binary, so the machine could read and modify its own instructions as it executed. The arithmetic unit would perform binary operations while a control mechanism fetched instructions sequentially from memory, altering the sequence through conditional operations. The report emphasized automatic sequence control, addressable memory locations for both numeric values and program orders, and the practicality of electronic switching elements for high-speed computation.

Architectural model
The model laid out in the report identified essential components that later became standard terminology: a central memory, an arithmetic or logical unit, a control unit to interpret instructions, and input/output mechanisms. Instructions were conceived as coded orders stored in memory and treated as data when necessary, enabling jumps, conditional branching, and subroutines. The resulting framework provided a clear separation of concerns between storage, computation, and control while demonstrating how a single memory model could support complex, programmable behavior.

Programming and operational implications
Treating code and data in the same storage space introduced powerful programming possibilities and new challenges. The report described mechanisms for addressing, instruction formats, and conditional control that allowed more compact and flexible programs than earlier fixed-wiring designs. At the same time, the approach permitted self-modifying code and required careful conventions for program organization and debugging. Von Neumann's attention to practical implementation, timing of operations, sequencing of arithmetic steps, and encoding choices, helped bridge abstract mathematical ideas and workable machine designs.

Impact and legacy
The First Draft became a touchstone for subsequent machine designs and is widely credited with codifying the "von Neumann architecture" that underlies most modern general-purpose computers. Its circulation accelerated adoption of stored-program machines such as EDVAC, the Manchester Baby, and machines developed at Princeton, Manchester, and elsewhere. Over time the single-memory model led to recognized trade-offs, notably the throughput limit between CPU and memory often called the "von Neumann bottleneck," but the report's fundamental insight, that programs could be represented and manipulated as data, remains central to computing. The document's influence extended beyond hardware into software practices, teaching, and the conceptual foundations used to reason about computation for decades.