System Support Program (SSP) was the operating system of the IBM System/34 and System/36 minicomputers. SSP was a command-based operating system released in 1977.
History
SSP originally contained 60 or so commands that were implemented on the System/34 from 1977 to 1983 in different versions called releases. Release 1 was issued with the original S/34 in 1977. Release 9 was issued in 1981. In 1983, IBM repackaged SSP on a new computer called the IBM System/36, which was not object-code compatible with the S/34. In 1994, IBM repackaged SSP on an updated model of the S/36 called the Advanced/36. The A/36 was an IBM AS/400 which had the SSP implemented as a "virtual machine".
Major releases of SSP include: S/34 S/34 Release 1.0 – this was shipped with the first S/34 in 1977. S/34 Release 8.0 – this seems to have been issued about 1980. S/34 Release 9.0 – this was the last release for the S/34 c.1980. S/36 S/36 Release 1.0 – this was apparently shipped with the first S/36 in 1983. S/36 Release 2.0 – this release supported the 8809-tape drive. S/36 Release 4.0 – this was the release where S/36 was given 5 job queues. S/36 Release 5.1 – this 1988 release was the last major change on 536X platforms. S/36 Release 6.0 – also known as the VASP or Value-Added Support Product, this release added functionality that allowed program calls in RPG, and it also provided software to calculate the size AS/400 that the user would need when upgrading. The VASP was controversial. Rumours circulated in the industry papers that the customer could not go back to 5.1 if 6.0 did not function adequately. Program calls with RPG CALL/PARM were inferior to RPGIII designs and inferior to customer add-on products. S/36 Release 7.1 – this 1994 release was shipped with the Advanced/36 (9402-236 models). The first A/36 machines would not function on a lower release and were also incompatible with 7.5 (while technically, true, program object code from a 7.1 machine would run on a 7.5 and vice versa, plus many 9402-236's were upgraded to 9402-436, which they changed out the motherboard and installed some new LIC code and you restored on a copy of your files and voila, it all worked). Rumours circulated that stated prior release compilers would not function on the Advanced/36, but they proved unfounded. There were reasons a programmer would rather use the 5.1 RPGII compiler instead of the presumably more advanced 7.x compiler. S/36 Release 7.5 – this 1995 release was shipped with the second and final wave of the Advanced/36 (9402-436). Functions like WRKSYSVL allowed the operator to change the system time on the fly, which was interesting because customer add-ons to do this through assembler subroutines did not function on the Advanced/36. However, assembler routines to do things like open/close files, retrieve the VTOC, etc. functioned just fine on 7.1 and 7.5 Guest/36 – this is Release 7.5, but you could set up an M36 (a guest) on an AS/400 (running OS/400 V3R6 thru V4R4), and it would function just like the 9402-436, except that in addition to having this guest "partition", you also had OS/400 if you wanted it. So, if the 9402-436 which came in 3 speeds 2102, 2104 and 2106 (which the latter was about 2.7X faster than the base) wasn't fast enough, you could get a 9406-xxx machine and install a "guest/36" on such. And actually, you could install more than one guest/36. There were some limitations of number of attached workstations but having two guest/36's running on an AS/400 and setting up DDM (distributed data management) between them and even with OS/400 to host large files, could easily be done. While the S/36 and A/36 for the most part worked only with twinax attached terminals, on a Guest/36 (or M/36), you could have all your terminals be on a LAN running tcp/ip and be virtual devices in the Guest/36 environment. S36EE (S/36 execution environment) – this was supported native on the AS/400 and its follow on (iSeries, IBM i), which allows a user to continue to run their s/36 programs and procedures without having to convert them. Many of the system procs also work with such. While it was typically "slower" since it has to go through additional steps, however today with such fast machines, the speed of an S36EE is many times faster than the A/36 execution speed. Example, one job took 12 minutes to run on an Adv/36, took 20 seconds to run in S36EE mode. The object code however is NOT compatible with the previous S/36 and A/36, meaning that one had to recompile all programs and menus. However, one advantage is that you can not only run S36EE but also OS/400 applications. You can access database tables in your S/36 programs, you can call RPG/400 and RPGIV programs from with a S/36 program.