The Free On-line Dictionary of Computing (30 December 2018):

IBM System/36

    A mid-range computer introduced in 1983, which
   remained popular in the 1990s because of its low cost and high
   performance.  Prices started in the $20k range for the small
   5362 to $100+k for the expanded 5360.  In 1994, IBM introduced
   the Advanced 36 for $9,000.

   The largest 5360 had 7MB of RAM and 1432MB of hard disk.
   The smallest 5362 had 256K of RAM and 30MB of hard disk.  The
   Advanced 36 had 64MB of RAM and 4300MB of hard disk, but
   design issues limit the amount of storage that can actually be
   addressed by the operating system; underlying microcode
   allowed additional RAM to cache disk reads and writes,
   allowing the Advanced 36 to outperform the S/36 by 600 to
   800%.

   There was only one operating system for the S/36: SSP (System
   Support Product).  SSP consumed about 7-10MB of hard drive
   space.  Computer programs on the S/36 reside in "libraries,"
   and the SSP itself resides in a special system library called
   #LIBRARY.

   Components of SSP include the Data File Utility (DFU), the
   Source Entry Utility (SEU), the largely obselete Work
   Station Utility (WSU), the Screen Design Aid (SDA) and
   Operational Control Language (OCL).

   Using the IBM S/36 is relatively simple.  The operator sits in
   front of a computer monitor, types on a keyboard, and
   interacts using a series of on-screen forms.  S/36 is
   command-oriented, like MS-DOS, however, S/36 additionally uses
   more than 70 menus which allow operators to type the number of
   an appropriate command or response, and application writers
   can create their own menus and commands ("procedures.")

   Programmers use SEU to create or modify a source program
   which is then compiled into an object program.  SEU uses 50
   or so templates to assist the operator with the syntax of
   different types of sources.

   By 1985, an application called Programmer/Operator
   Productivity was widely available and was probably the most
   popular (and pirated) S/36 software ever written.  POP
   included a full-screen editor called FSEDIT which could be
   used in place of SEU, which only allowed single-line editing.

   Data File Utility allows the programmer to quickly create a
   simple, single-record display program to add, update and
   delete records within a file.  Also, simple report programs
   can be created.

   Screen Design Aid allows the programmer to create menus,
   create and update simple forms which are called "display
   formats" or "prompt screens", and view existing display
   formats.

   By using Operational Control Language, the programmer can
   assign files and resources to a particular program and pass
   run-time information like a processing date, order number, or
   user name to the compiled program.  Programs can acquire up to
   8 workstations, or run in the background, but usually they run
   on only one workstation.  The largest program size is 64K.

   Whenever a program is called, SSP searches in the named user
   library and then #LIBRARY.  Therefore, a system program can be
   called from any library and all users have access to it.

   S/36 has three types of security: (1) password security, (2) a
   badge reader option that almost no-one ever bought, and (3)
   resource security.  There are five levels of users access and
   five levels of resource access.  By using password and
   resource security effectively, the administrator (who was at
   that time often called a DP Manager or Information Systems
   Manager) can restrict access to critical and secure
   applications.

   The cheapest, and therefore most popular, language compiler
   for the S/36 is RPG II, a language based on fixed logic
   cycles which arose in the days of card readers.  Other
   languages include COBOL, FORTRAN and BASIC.  Almost
   every S/36 shop with in-house design uses RPG.

   It's interesting to note that the S/36 allows the operator to
   change a program while it is being used, which can be very
   dangerous on live data.  The S/38 and the iSeries computer do
   not allow this.

   IBM has not marketed the S/36 or Advanced 36 since 2000.
   Price/performance of the AS/400 (aka iSeries) and hardware
   technology of the present-generation PC makes the S/36 a
   much less attractive offering from a different era in
   computing.

   (2005-04-05)