IBM System/370

People using a 370

The System/370 continued the tradition of the prior System/360 by expanding the instruction set, and adding hardware support for both virtual memory (except for the first two models announced), and the new ability of virtualization.

They ran a variety of software, such as MVS, and the newer VM/370.

The System/370 was supplanted by the S/390.

Specs

• Sixteen 32-bit control registers, in supervisor mode only
• Sixteen 32-bit general purpose registers
• Four 64-bit floating point registers (could be paired as two 128-bit floating point registers)
• 24 bit address space for a maximum 16MB of RAM (later models: 31 bits)

Models

Model	Announced	Shipped	Withdrawn
115	13 March, 1973	March, 1974	9 March, 1981
115-2	10 November, 1975	April, 1976	9 March, 1981
125	4 October, 1972	April, 1973	9 March, 1981
125-2	10 November, 1975	February, 1976	9 March, 1981
135	8 March, 1971	April, 1972	16 October, 1979
135-3	30 June, 1976	February, 1977	16 October, 1979
138	30 June, 1976	November, 1976	1 November, 1983
145	23 September, 1970	June, 1971	10 November, 1971
145-3	30 June, 1976	May, 1977	16 October, 1979
148	30 June, 1976	January, 1977	1 November, 1983
155	30 June, 1970	January, 1971	23 December, 1977
158	2 August, 1972	April, 1973	15 September, 1980
158-3	26 October, 1976	September, 1976	15 September, 1980
165	30 June, 1970	April, 1971	23 December, 1977
168	2 August, 1972	May, 1973	15 September, 1980
168-3	18 February, 1976	June, 1976	15 September, 1980
195	30 June, 1970	August, 1973	9 February, 1977

Virtual memory hardware upgrades for the Models 155 and 165 (the only S/370 models which did not support virtual memory) were announced shortly after the announcement of the Models 158 and 168, but were available only to customers who already owned a Model 155 or 165. When this was installed, these models were known as 155-II's and 165-II's.

An Attached Processor (AP) version of the Model 158, and multi-processor versions of the Models 158 and 168, were made available in 1976; these are the “-3” updates.

Games

Well thankfully there seems to have been some games....

• Zork

Emulation

The 370 can be emulated by the following emulators:

• Hercules
• PC/370

See also

• IBM I/O channel

Further reading

• Emerson W. Pugh, Lyle R. Johnson, John H. Palmer, IBM's 360 and Early 370 Systems, MIT Press, Cambridge, 1991

External link

• System/370 - Dates and characteristics