IBM PC Server System/390

The P/390 is basically an IBM mainframe system adapted to run on a personal computer. A P/390 comes on a single card that contains a System/390 instruction set, allowing operating systems such as OS/390, MVS, VM, and VSE, to be installed. The P/390 makes it possible to develop, test, and run application programs written for the mainframe on a smaller, more economical machine. After testing, programs that require mainframe capability can be moved to the mainframe. A common use of the P/390 today is for 2000 analysis and testing. The P/390 is sold as part of a PC workstation that also comes with an OS/2 operating system. The entire product is called the IBM PC Server System/390. The MVS and OS/390 operating systems require 128 megabyes of RAM. VM and VSE will install with 32 megabytes.

An R/390 is the P/390-PCI card installed on IBM's RS/6000 server. Both products are sold both as development environments and as economical approaches for companies with older mainframe systems to move their legacy applications to a new production environment.

S/390 Processor Card
An important goal in the design of the S/390 Processor Card was complete compatibility with existing mainframe operating systems and software. The processor implements all of the ESA/390 and XA instructions which prevents the need for instruction translation. There are three generations of the card:


 * The original S/390 Processor Card incorporated 32MB of dedicated memory, with optional 32MB or 96MB daughter cards, for a combined total of 64MB or 128MB of RAM. The processor was officially rated at 4.5 MIPS. It was built to plug into a Micro Channel architecture host system.
 * The second version was built for a PCI host system. It included 128 MB of dedicated memory as standard, and was still rated at 4.5 MIPS.
 * The third version, referred to as a P/390E card (for Enhanced), included 256 MB of dedicated memory and was rated at 7 MIPS. It, too, was built for a PCI host system. There was an extremely rare (possibly only ever released as pre-production samples) 1 GB memory version of the P/390E card.

Links

 * P/390 Information
 * PC-based IBM-compatible mainframes (Wikipedia)