 | This article needs additional citations for
verification. (April 2023) |
| History of IBM mainframes, 1952–present |
|---|
| Market name |
| Architecture |
IBM Enterprise Systems Architecture is an instruction set architecture introduced by IBM as ESA/370 in 1988. It is based on the IBM System/370-XA architecture.
It extended the dual-address-space mechanism introduced in later IBM System/370 models by adding a new mode in which general-purpose registers 1-15 are each associated with an access register referring to an address space, with instruction operands whose address is computed with a given general-purpose register as a base register will be in the address space referred to by the corresponding address register.
The later ESA/390, introduced in 1990, added a facility to allow device descriptions to be read using channel commands and, in later models, added instructions to perform IEEE 754 floating-point operations and increased the number of floating-point registers from 4 to 16.
Enterprise Systems Architecture is essentially a 32-bit architecture; as with System/360, System/370, and 370-XA, the general-purpose registers are 32 bits long, and the arithmetic instructions support 32-bit arithmetic. Only byte-addressable real memory (Central Storage) and Virtual Storage addressing is limited to 31 bits, as is the case with 370-XA. (IBM reserved the most significant bit to easily support applications expecting 24-bit addressing, as well as to sidestep a problem with extending two instructions to handle 32-bit unsigned addresses.) It maintains problem state backward compatibility dating back to 1964 with the 24-bit-address/32-bit-data ( System/360 and System/370) and subsequent 24/31-bit-address/32-bit-data architecture ( System/370-XA). However, the I/O subsystem is based on System/370 Extended Architecture (S/370-XA), not on the original S/370 I/O instructions.
ESA/370 architecture
![[icon]](/info/en/?search=File:Wiki_letter_w_cropped.svg){kind=small} | This section needs expansion. You can help by
adding to it. (April 2023) |
| Designer | IBM |
|---|---|
| Bits | 32-bit |
| Introduced | 1988 |
| Design | CISC |
| Type | Register–Register Register–Memory Memory–Memory |
| Encoding | Variable (2, 4 or 6 bytes long) |
| Branching | Condition code, indexing, counting |
| Endianness | Big |
| Predecessor | System/370-XA |
| Successor | ESA/390 |
| Registers | |
| General-purpose | 16 |
| Floating point | 4 64-bit |
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On February 15, 1988, IBM announced [6] [7] Enterprise Systems Architecture/370 (ESA/370) for 3090 enhanced ("E") models and for 4381 model groups 91E and 92E.
In addition to the primary-space and secondary-space addressing modes that later System/370 models, and System/370 Extended Architecture (S/370-XA) models, support, ESA has an access register mode in which each use of general register 1-15 as a base register uses an associated access register to select an address space. [8] In addition to the normal address spaces that machines with the dual-address-space facility support, ESA also allows data spaces, which contain no executable code.
ESA/390 architecture
| Designer | IBM |
|---|---|
| Bits | 32-bit |
| Introduced | 1990 |
| Design | CISC |
| Type | Register–Register Register–Memory Memory–Memory |
| Encoding | Variable (2, 4 or 6 bytes long) |
| Branching | Condition code, indexing, counting |
| Endianness | Big |
| Predecessor | ESA/370 |
| Successor | z/Architecture |
| Registers | |
| General-purpose | 16 |
| Floating point | 4 64-bit up to the G4; 16 64-bit starting with the G5 [9] |
A machine may be divided into Logical Partitions ( LPARs), each with its own virtual system memory so that multiple operating systems may run concurrently on one machine.
An important capability to form a Parallel Sysplex was added to the architecture in 1994.
ESA/390 also extends the Sense ID command to provide additional information about a device, and additional device-dependent channel commands, the command codes for which are provided in the Sense ID information, to allow device description information to be fetched from a device. [10]: 1-8 [11]
Some PC-based IBM-compatible mainframes which provide ESA/390 processors in smaller machines have been released over time, but are only intended for software development.
New channel commands
The following channel commands [d] are new, or have their functionality changed, in ESA/390: [11]
| Command | Bit Position | |||||||
|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
| Read configuration data | D | D | D | D | D | D | D | 0 |
| Read node identifier | D | D | D | D | D | D | D | 0 |
| Sense ID | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Set interface identifier | D | D | D | D | D | D | D | 1 |
| Note: D Device dependent. The command code, if any, recognized by an I/O device may be obtained by using a sense-ID command. | ||||||||
Notes
-
^ The number and format of floating-point registers depends on the installed features:
- ESA/370
ESA/390 without the Advanced Floating Point (AFP) facility - Only the hexadecimal floating point (HFP) registers FP0, FP2, FP4 and FP6 exist
- ESA/390 with the AFP facility
- FP0_FP15 may be HFP or IEEE floating point
- ESA/370
- ^ Bit 22 is renamed as HFP exponent underflow in ESA/390
- ^ Bit 23 is renamed as HFP significance in ESA/390
- ^ The data returned by Sense ID include the command codes for Read configuration data, Read node identifier and Set interface identifier.
References
- S370-ESA
- IBM Enterprise Systems Architecture/370 Principles of Operation (PDF) (First ed.). IBM. August 1988. SA22-7200-0.
- S/390-ESA
- IBM Enterprise Systems Architecture/390 Principles of Operation (PDF) (Ninth ed.). IBM. June 2003. SA22-7201-08.
- ^ S370-ESA, p. 5-30, Access-list-Entry Token.
- ^ S370-ESA, pp. 4-7–4-9, Figure 4-3 Assignment of Control-Register Fields.
- ^ S390-ESA, pp. 4-8–4-10, Figure 4-3 Assignment of Control-Register Fields.
- ^ S370-ESA, p. 4-5, Program-Status-Word Format.
- ^ S390-ESA, p. 4-5, Program-Status-Word Format.
- ^ "IBM 3090 PROCESSOR UNIT MODELS 280E AND 500E AND IBM 3090 PROCESSOR UNIT MODEL 300E TO 400E UPGRADE". Announcement Letters. IBM. February 15, 1988. 188-038.
- ^ "ENTERPRISE SYSTEMS ARCHITECTURE/370 (TM) AND MVS/SYSTEM PRODUCT VERSION 3". Announcement Letters. IBM. February 15, 1988. 288-059.
- ^ S370-ESA.
- ^ Slegel, Timothy J. (August 17, 1998). "IBM S/390 G5 Microprocessor" (PDF). Hot Chips.
- ^ S390-ESA.
- ^ a b Enterprise Systems Architecture/390 Common I/O-Device Commands, Second Edition, IBM, April 1992, SA22-7204-01
| This article needs additional citations for
verification. (April 2023) |
| History of IBM mainframes, 1952–present |
|---|
| Market name |
| Architecture |
IBM Enterprise Systems Architecture is an instruction set architecture introduced by IBM as ESA/370 in 1988. It is based on the IBM System/370-XA architecture.
It extended the dual-address-space mechanism introduced in later IBM System/370 models by adding a new mode in which general-purpose registers 1-15 are each associated with an access register referring to an address space, with instruction operands whose address is computed with a given general-purpose register as a base register will be in the address space referred to by the corresponding address register.
The later ESA/390, introduced in 1990, added a facility to allow device descriptions to be read using channel commands and, in later models, added instructions to perform IEEE 754 floating-point operations and increased the number of floating-point registers from 4 to 16.
Enterprise Systems Architecture is essentially a 32-bit architecture; as with System/360, System/370, and 370-XA, the general-purpose registers are 32 bits long, and the arithmetic instructions support 32-bit arithmetic. Only byte-addressable real memory (Central Storage) and Virtual Storage addressing is limited to 31 bits, as is the case with 370-XA. (IBM reserved the most significant bit to easily support applications expecting 24-bit addressing, as well as to sidestep a problem with extending two instructions to handle 32-bit unsigned addresses.) It maintains problem state backward compatibility dating back to 1964 with the 24-bit-address/32-bit-data ( System/360 and System/370) and subsequent 24/31-bit-address/32-bit-data architecture ( System/370-XA). However, the I/O subsystem is based on System/370 Extended Architecture (S/370-XA), not on the original S/370 I/O instructions.
ESA/370 architecture
|
| This section needs expansion. You can help by
adding to it. (April 2023) |
| Designer | IBM |
|---|---|
| Bits | 32-bit |
| Introduced | 1988 |
| Design | CISC |
| Type | Register–Register Register–Memory Memory–Memory |
| Encoding | Variable (2, 4 or 6 bytes long) |
| Branching | Condition code, indexing, counting |
| Endianness | Big |
| Predecessor | System/370-XA |
| Successor | ESA/390 |
| Registers | |
| General-purpose | 16 |
| Floating point | 4 64-bit |
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On February 15, 1988, IBM announced [6] [7] Enterprise Systems Architecture/370 (ESA/370) for 3090 enhanced ("E") models and for 4381 model groups 91E and 92E.
In addition to the primary-space and secondary-space addressing modes that later System/370 models, and System/370 Extended Architecture (S/370-XA) models, support, ESA has an access register mode in which each use of general register 1-15 as a base register uses an associated access register to select an address space. [8] In addition to the normal address spaces that machines with the dual-address-space facility support, ESA also allows data spaces, which contain no executable code.
ESA/390 architecture
| Designer | IBM |
|---|---|
| Bits | 32-bit |
| Introduced | 1990 |
| Design | CISC |
| Type | Register–Register Register–Memory Memory–Memory |
| Encoding | Variable (2, 4 or 6 bytes long) |
| Branching | Condition code, indexing, counting |
| Endianness | Big |
| Predecessor | ESA/370 |
| Successor | z/Architecture |
| Registers | |
| General-purpose | 16 |
| Floating point | 4 64-bit up to the G4; 16 64-bit starting with the G5 [9] |
A machine may be divided into Logical Partitions ( LPARs), each with its own virtual system memory so that multiple operating systems may run concurrently on one machine.
An important capability to form a Parallel Sysplex was added to the architecture in 1994.
ESA/390 also extends the Sense ID command to provide additional information about a device, and additional device-dependent channel commands, the command codes for which are provided in the Sense ID information, to allow device description information to be fetched from a device. [10]: 1-8 [11]
Some PC-based IBM-compatible mainframes which provide ESA/390 processors in smaller machines have been released over time, but are only intended for software development.
New channel commands
The following channel commands [d] are new, or have their functionality changed, in ESA/390: [11]
| Command | Bit Position | |||||||
|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
| Read configuration data | D | D | D | D | D | D | D | 0 |
| Read node identifier | D | D | D | D | D | D | D | 0 |
| Sense ID | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Set interface identifier | D | D | D | D | D | D | D | 1 |
| Note: D Device dependent. The command code, if any, recognized by an I/O device may be obtained by using a sense-ID command. | ||||||||
Notes
-
^ The number and format of floating-point registers depends on the installed features:
- ESA/370
ESA/390 without the Advanced Floating Point (AFP) facility - Only the hexadecimal floating point (HFP) registers FP0, FP2, FP4 and FP6 exist
- ESA/390 with the AFP facility
- FP0_FP15 may be HFP or IEEE floating point
- ESA/370
- ^ Bit 22 is renamed as HFP exponent underflow in ESA/390
- ^ Bit 23 is renamed as HFP significance in ESA/390
- ^ The data returned by Sense ID include the command codes for Read configuration data, Read node identifier and Set interface identifier.
References
- S370-ESA
- IBM Enterprise Systems Architecture/370 Principles of Operation (PDF) (First ed.). IBM. August 1988. SA22-7200-0.
- S/390-ESA
- IBM Enterprise Systems Architecture/390 Principles of Operation (PDF) (Ninth ed.). IBM. June 2003. SA22-7201-08.
- ^ S370-ESA, p. 5-30, Access-list-Entry Token.
- ^ S370-ESA, pp. 4-7–4-9, Figure 4-3 Assignment of Control-Register Fields.
- ^ S390-ESA, pp. 4-8–4-10, Figure 4-3 Assignment of Control-Register Fields.
- ^ S370-ESA, p. 4-5, Program-Status-Word Format.
- ^ S390-ESA, p. 4-5, Program-Status-Word Format.
- ^ "IBM 3090 PROCESSOR UNIT MODELS 280E AND 500E AND IBM 3090 PROCESSOR UNIT MODEL 300E TO 400E UPGRADE". Announcement Letters. IBM. February 15, 1988. 188-038.
- ^ "ENTERPRISE SYSTEMS ARCHITECTURE/370 (TM) AND MVS/SYSTEM PRODUCT VERSION 3". Announcement Letters. IBM. February 15, 1988. 288-059.
- ^ S370-ESA.
- ^ Slegel, Timothy J. (August 17, 1998). "IBM S/390 G5 Microprocessor" (PDF). Hot Chips.
- ^ S390-ESA.
- ^ a b Enterprise Systems Architecture/390 Common I/O-Device Commands, Second Edition, IBM, April 1992, SA22-7204-01