IBM 7030 Stretch

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IBM 7030 (Stretch)
Manufacturer: International Business Machines
Year Announced: late 1956
Year Design Started: late 1954; formal project start January 1956
Year First Shipped: April, 1961
Year Discontinued: May, 1961
Form Factor: mainframe
Word Size: 64 bits
Logic Type: ECL using drift transistors
Memory Speed: 2.1 µsec
Physical Address Size: 18 bits (256K words)
Virtual Address Size: 18 bits
Price: US$7.8M (reduced from US$13.5M)


The IBM 7030 (a product of Project Stretch, so it was often called by some variant of that) was a ground-breaking and influential mainframe from IBM, arguably the first supercomputer. It was the fastest computer in the world from 1961 until the advent of the CDC 6600 in 1964.

Although initially considered a commercial failure by IBM, it was later recognized as the foundation of the success of the IBM System/360; both its technology (it was the first machine IBM built with transistors, and Stretch hardware was used directly in the IBM 7090), and many of its architectural innovations were used there, especially in the higher-performance models of the /360 line. Indeed, many of them (such as pipelines) are still in use today, and important.

The initial goal was a performance 100 times that of the IBM 704; this target was not met, but the 7030 was roughly 30 times as fast (the exact multiplier depends on the problem, due to the large amount of overlap between successive instructions).

It also introduced the concept of the 8-bit byte, although the CPU could address individual bits.

The logic used was basically ECL, in that it used "switching (or steering) a constant current .. toward [either] output". The CPU alone contained no less than 169,000 discrete transistors, packaged in wat was effectively an early form of Standard Modular System cards. The main memory used interleaving (up to 4-way, depending on the number of memory banks installed) to increase the memory bandwidth.

It was intended from the start to be used in multi-programming mode; the system included what was effectively base and bounds memory management.

Further reading

  • Werner Buchholz (editor), Planning a Computer System: Project Stretch, McGraw-Hill, New York, 1962