Web-based IBM 1620 emulator and IPL-V from 1963

summary

The retro-1620 project aims to preserve the IBM 1620 Model-2 by creating a web-based emulator and recovering legacy software. This 1960s computer was designed as an affordable scientific tool using a unique decimal, variable field-length architecture. By digitizing the hardware and operating environment, the project ensures that the historical computing methods of the 1620 are accessible to modern users. The effort combines technical emulation of the memory-to-memory architecture with an archival effort to save old programs.

key points

1. The IBM 1620 utilized a two-address memory-to-memory architecture without software-accessible registers, processing data digit-sequentially. Memory consisted of binary-coded decimal values with a fifth flag bit used for signs and delimiters.
2. The Model 2 improved upon the Model 1 by doubling memory cycle speed and implementing hardware addition, though it still relied on lookup tables for multiplication. It also introduced optional index registers and support for binary bit-wise operations.
3. The system supported a wide range of peripherals including paper tape, punched cards, and disk drives, often running the SPS assembler or FORTRAN II. For those with disk drives, a batch operating system called 'Monitor' managed the workflow.

who should read it

Computer historians and enthusiasts of vintage hardware who want to understand early scientific computing. Developers interested in the emulation of non-binary, decimal-based architectures.

discussion positive