Browse Prior Art Database

The AS/400 Advanced 36

IP.com Disclosure Number: IPCOM000118076D
Original Publication Date: 1996-Sep-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 146K

Publishing Venue

IBM

Related People

Dahl, SA: AUTHOR [+2]

Abstract

The AS/400* Advanced 36 provides an object code compatible follow-on product for System/36* customers by emulating the System/36 architecture using 64-bit Reduced Instruction Set Computer/Cycles (RISC) technology.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 40% of the total text.

The AS/400 Advanced 36

      The AS/400* Advanced 36 provides an object code compatible
follow-on product for System/36* customers by emulating the System/36
architecture using 64-bit Reduced Instruction Set Computer/Cycles
(RISC) technology.

      This invention provides a cost-effective mechanism for
emulating the System/36 architecture without requiring continued
development of System/36 hardware.  The System/36 architecture is
emulated using 64-bit RISC technology that will be used all across
the AS/400 product line.  Therefore, this invention provides a
mechanism for supporting both the OS/400* operating system and the
System/36 operating system on a single hardware platform.  The
emulation is provided in three different areas:
  o  Main Store Processor (MSP) instruction emulation
       The System/36 MSP is where all of the System/36 licensed
      programs and applications execute.  In order to provide
      complete object code compatibility, the MSP instruction set
      was emulated directly.
  o  MSP addressing
       Many of the operating system components as well as some
      applications were very dependent on System/36 addressing.  The
      view of storage from these programs also required precise
      emulation to allow them to operate correctly.
  o  Control Store Processor (CSP) supervisor
       While no application programs were executed out of the
      System/36 CSP, the CSP did provide functions on behalf of
      the operating system and applications.  These functions
      are provided by rewriting the CSP code in object oriented
      C++.  In addition, by rewriting this code instead of emulating
      it, a significant increase in performance is obtained.

      The System/36 emulation capability has been integrated into
AS/400 Licensed Internal Code (LIC).  This permits OS/400 to run on
the identical hardware in the future which provides for much easier
migration to OS/400.  For example:

      The System/36 disk space is simulated using a set of LIC
segments.  The segments are all 8 MB in size.  Up to 512 segments may
be allocated to simulate the System/36 maximum of 4 GB disk space.  A
single 8 MB segment is used to simulate System/36 main store.  Since
both simulated main store and simulated disk space are based on LIC
segments, they can be paged in and out of real main store by LIC
storage management.  This removes the need for a separate manager
within the emulator and allows any System/36 data or program to be
paged anywhere in real main store.  These segments can then share
main store with OS/400 segments in the future.

      The Advanced 36 emulator is structured as a MSP processor
emulation task and several Input/Output (I/O) emulation tasks.  Fig.
1 shows the overall relationship of these tasks.  All I/O requests
are detected by the MSP emulator task and sent to the appropriate I/O
tas...