AS/400

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Image:I5-570.jpg The Application System/400 (also known as AS/400, iSeries (since 2000) and System i5 (since 2006)) is a type of minicomputer produced by IBM. It was first produced in 1988 and, as of 2006, is still in production.

1 Features
2 History
3 Hardware
- 3.1 CPU in AS/400, iSeries, i5
- 3.2 Models of AS/400, iSeries, i5 Systems
4 See also
5 References
6 External links

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Features

The AS/400 is an object-based system with an integrated DB2 database that was designed to implement E. F. Codd's relational database model, which is based on Codd's 12 rules, in the operating system and hardware.

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Instruction set

The AS/400 survives because its instruction set (called TIMI for "Technology Independent Machine Interface" by IBM) allows the operating system and application programs to take advantage of advances in hardware and software without recompilation. TIMI is a virtual instruction set, which means that it is not possible for user-mode programs to utilize the instruction set of the underlying CPU, thus ensuring hardware independence. This is conceptually somewhat similar to the virtual machine architecture of programming environments such as Smalltalk, Java and .NET. The key difference is that it is embedded so deeply into the AS/400's design as to make all applications and even the bulk of its operating systems binary-compatible across different processor families.

Note that, unlike other virtual-machine architectures in which the virtual instructions are interpreted at runtime, TIMI instructions are never interpreted. They constitute an intermediate compile time step and are translated into the processor's instruction set as the final compilation step. The TIMI instructions are stored within the final program object, in addition to the executable machine instructions. This is how a program compiled on one processor family (eg. CISC) can be moved to a new processor (eg. PowerPC) without re-compilation. The program is saved from the old machine and restored onto the new machine, whereupon the operating system discards the old machine instructions and re-translates the TIMI instructions into machine instructions for the new processor.

The AS/400's instruction set defines all pointers as 128-bit. This is one of the surviving features of the System/38, which used the 128-bit address space to enable all devices, including disk and tape storage, to be directly addressable.

The S/38 used 48 bit addressing. This was expanded to 64 bits with the original release of the AS/400.

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Software

Image:Debian linux on as400.jpg

The AS/400 includes an extensive library-based operating system, OS/400, and is also capable of supporting mutiple instances of AIX, Linux, Microsoft Windows 2000 and Windows Server 2003, with either single-processor internal blade servers (IXS) or externally-linked mutiple-processor servers (IXA).

LPAR (Logical PARtitioning), a feature introduced from IBM's mainframe computers, facilitates running multiple operating systems simultaneously on one AS/400 unit. A system setup with LPAR can even run different operating systems on different partitions while ensuring that one OS cannot run over the memory or resources of another. Each LPAR is given a portion of system resources (memory, hard disk space, and CPU time) via a system of weights that determines where unused resources are allocated at any given time. The operating systems supported (and commonly used) under the LPAR scheme are OS/400, AIX and Linux.

Other features include an extremely fast database management system, a menu-driven interface, multi-user support, terminals (IBM 5250) and printers, security, communications, client-server and web-based applications. All software necessary to run the AS/400 is included and integrated. More than 2,500 business software applications were available when the first AS/400 was delivered in 1988. Applications can run without modification on any model in the product line, from small, single-processor machines up to those with 64 multi-core CPUs, due to the AS/400's virtual instruction set.

iSeries servers also support common client-server-based technologies such as ODBC and JDBC for accessing its database from client-based software, created with languages such as Java, Microsoft Visual Studio .NET and other languages.

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Programming

Programming languages available for the AS/400 include RPG, assembly language, C, [[C++]], Java, COBOL, SQL, BASIC, PHP, PL/I, and REXX. Several CASE tools are available: Synon, AS/SET, Magic, and Lansa.

Commands in the Control Language (CL) are promptable and most provide cursor-sensitive help to make entering parameters easier. A command name consists of a three-letter verb and a subject part, also referred to as a noun. Some command names provide a "modifier" as well. This is intended to make it easy to understand CL code.

Examples:

CRTUSRPRF - Create (verb) user (modifier) profile (noun)
DLTLIB - Delete (verb) library (noun)
CPYF - Copy file
WRKACTJOB - Work with Active Jobs

For traditional business programming languages such as RPG, COBOL, C and SQL, the AS/400 has support for external files, display files and object-oriented programming, which allows for increased programming productivity. It also supports Unix-like file directories, industry-leading support for Java, client-server technologies and a native Apache web server, for "modern" and GUI-style applications.

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Integrated Language Environment

Despite the lack of a "UNIXy" background, the AS/400 has, over the years, picked up the programming/runtime model found on UNIX, Linux, and PC systems. Traditional AS/400 programming is a "one-stop shop", where a programmer writes computer code, compiles the code, and then executes the code. There is no link step that is found in other environments.

However, in 1995, that changed. IBM re-christened the one-stop shop programming style "OPM" (for Original Programming Model) and introduced a new language paradigm called "ILE" (for Integrated Language Environment). ILE had significant enhancements over OPM, including the ability to create modules (similar to .obj or .lib files), and then bind (link) the modules together into a single executable. The executable could be created as a program or a service program (service programs are similar to .lib or .dll files).

The real power of the ILE environment is in the "integrated" aspect, however. Modules in ILE-compliant languages (RPG, COBOL, C, C++, and CL) could be created and bound together. For the first time, AS/400 programmers could exploit the strengths of multiple ILE-compliant languages in a single program. Also, with the introduction of service programs, standard routines could be externalized more easily, and modularity increased. To ensure proper migration to the ILE environment, OPM RPG and COBOL programs could be migrated to ILE easily.

Interoperation with the Java language is also supported, though not as tightly as with the ILE languages. The iSeries Java implementation is distinguished by the degree to which it is embedded in the operating system.

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History

The AS/400 was the result of the combination of the System/38 database machine (announced by IBM in October 1978 and delivered in August 1979) and the System/36. The first AS/400 systems (known by the development code names Silverlake and Olympic) were delivered in 1988, and the product line has been refreshed continually since then. The programmers who worked on OS/400, the operating system of the AS/400, did not have a UNIX background. Dr Frank Soltis, the chief architect, says that this is the main difference between this and any other operating system.

The AS/400 was the first general-purpose computer system to attain a C2 security rating from the NSA, and in 1995 was extended to employ a 64-bit processor and operating system.

In 2000 IBM renamed the AS/400 to iSeries, as part of its e-Server branding initiative. The product line was further extended in 2004 with the introduction of the i5 servers, the first to utilize the IBM POWER5 processor. The architecture of the system allows for future implementation of 128-bit processors when they become available. Existing programs will utilize the new hardware without modification.

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Hardware

The AS/400 was originally based on a custom IBM CISC CPU which used a CPU architecture known as Internal MicroProgrammed Interface (IMPI) and an instruction set similar to the IBM 370. It was later migrated to a PowerPC-based RISC CPU family eventually known as RS64.<ref name="Soltis PowerPC">Template:Cite web</ref>

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CPU in AS/400, iSeries, i5

The System i5 uses IBM POWER CPUs. These CPUs are developed and manufactured by IBM. The POWER 4/5/5+ chips contain two cores. There are Multi-Chip Modules (MCM) available. They have 4 CPU (8 cores) or 8 CPUs (16 cores) in one MCM.

CPU	Year	Speed	Server-Model
Cobra (A10)	since 1995	55 or 75MHz	Model: 4xx, 5xx
Muskie (A25/A30)	since 1995	125 or 154MHz	Model: 53x
Apache (RS64) (A35)	since 1997	125MHz	Model: 6xx, 150
NorthStar; (RS64 II)	since 1998	200, 255 or 262MHz	Model: 170, 250, 7xx
Pulsar (RS64 III)	since 1999	450MHz	Model: 270, 820
IStar	since 2000	400, 500, 540 or 600MHz	Model: 820, 830, 840, SB2, SB3
SStar (RS64 IV)	since 2001	540, 600 or 750MHz	Model: 270, 800, 810, 820, 830, 840
POWER 4	since 2002	1,3 GHz	Model: 890
POWER 4	since 2003	1,1 or 1,3GHz	Model: 825, 870
POWER 5	since 2004	1,5 or 1,65 GHz	Model: i5-520; i5-550; i5-570; i5-595
POWER 5	since 2006	1,9 GHz	Model: i5-595
POWER 5+	since 2006	1,9 GHz 2,2 GHz	Model: i5-520, i5-550 Model: i5-570

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Models of AS/400, iSeries, i5 Systems

Model	Year	CPU Group	Base - CPW	OS/400 Release
B10,B20,B30,B35,B40,B45,B50,B60,B70	1988, 1989	P10, P20	2,9 - 20	V1R1 - V2R1
C04,C06,C10,C20,C25	1990	P10	3,1 - 6,1	V1R1 - V2R1
D02,D04,D06,D10,D20,D25,D35,D45,D50,D60,D70,D80	1991	P10,P20,P30	3,8 - 56,6	V2R2, V2R3
E02,E04,E06,E10,E20,E25,E35,E45,E50,E60,E70,E80,E90,E95	1992	P10,P20,P30,P40	4,5 - 116,6	?
F02,F04,F06,F10,F20,F25,F35,F45,F50,F60,F70,F80,F90,F95,F97	1993	P05,P10,P20,P30,P40	5,5 - 177,4	V2R3
P01, P02, P03	1993, 1994, 1995	P05	7,3 - 16,8	?
150	1996	P05	10,9 - 35,0	V4R1
S10, S20, S30, S40	1997	P05, P10, P20, P30, P40, P50	45,4 - 4550	V4R1, V4R2, V4R3
SB1, SB2, SB3	1997, 2000	P30, P40	1794 - 16500	V4R1, V4R3
10S, 100, 135, 140	1995, 1993	P05, P10, P20	17,1 - 65,6	?
170	1998	P05,P10,P20,	30 - 1090	V4R2
200, 20S, 236	1994	P05, P10	7,3 - 17,1	V3R0M5 (on model 236:V3R2)
250	2000	P05	50 - 75	V4R5
270	2000	P05, P10, P20	50 - 2350	V4R5 oder V5R1
300, 30S, 310	1994	P10,P20,P30,P40	11,6 - 177,4	V3R0M5 - V3R2
400, 40S, 436	1995	P05, P10	13,8 - 91,0	V3R6
500, 50S, 510, 530, 53S	1995	P10, P20, P30, P40	18,7 - 650	V3R6 - V4R3
600, 620, 640, 650	1997	P05, P10, P20, P30, P40, P50	22,7 - 4550	V4R1 - V4R3
720	1999	P10,P20,P30	240 - 1600	V4R3 - V5R1
730	1999	P20,P30,P40	560 - 2890	V4R3 - V5R1
740	1999	P40,P50	3660 - 4550	V4R3 - V5R1
800	2003	P05,P10	300 - 950	V5R2
810	2003	P10, P20	750 - 2700	V5R2
820	2000, 2001	P05,P10,P20,P30,P40	100 - 3700	V4R5, V5R1
825	2003	P30	3600 - 6600	V5R2
830	2000, 2002	P20,P30,P40,P50	1850 - 7350	V4R5, V5R1
840	2000,2001,2002	P40, P50	10000 - 20200	V4R5, V5R1
870	2002	P40,P50	7700 - 20000	V5R2
890	2002	P50, P60	20000 - 37400	V5R2
520	2004 - 2006	P05, P10, P20	500 - 7100	V5R3, V5R4
550	2004 - 2006	P20	3300 - 14000	V5R3, V5R4
570	2004 - 2006	P30, P40	3300 - 58500	V5R3, V5R4
595	2004 - 2006	P50, P60	24500 - 184000	V5R3, V5R4