- Arrives May 1962
- Features:
-
8-bit byte, 64-bit word
- Decimal, binary and floating-point arithmetic
- Reliable: acceptance was 90% uptime over a 5-day period
-
Instruction look-ahead (four levels deep)
- Address indirection to any depth
- Scatter/gather fields in word
-
MCP: Master Control Program ran one job at a time plus input/output wells
-
IBM Fortran IV compiler useless
- Compilation slower than IBM 7090
- Execution marginally better
- Alick Glennie's team at Aldermaston write three Fortran compilers in period 1962/64:
- S1: Fast Compilation (1962)
- S2: Basic Block Optimisation plus Fortran enhancements(1963)
- S3: Global Optimisation (installed on Atlas II) (1964)
