A few notes (recalled from memory (in 2003)) about IBM's System 370 machines.
These programs where written for IBM 3081 (1 CPU) and 3084 (4 CPU) machines (in 1993). The 370 series machines were 32 bit machines which had 16 general purpose registers (register 15 was the return code and and was only used for the RC). Also, the registers above R12 were used for reinterant information and it was a bad idea to use them. The OPCODEs are very easy to understand; 'L' is LOAD, 'LR' is LOAD REGISTER, 'LA' is LOAD ADDRESS, 'B' is BRANCH, 'BNE' is BRANCH (if) NOT EQUAL, etc.
VSAM was one of the very first databases, dating back to the late 1970s (?). VSAM stands for Virtual Sequential Access Method. It was a single keyed random access database (it could have secondary keys, tho, they were rare).
Note: All of these programs only required 512K to compile! (REGION=512K) Most of the object code was around 548 bytes to 2K! (The load DSN was the object (executable) file dataset)
-rw-r--r-- 1 bob dba 2213 Mar 9 1994 bob.load(gsiupd) -rw-r--r-- 1 bob dba 660 Mar 9 1994 bob.load(ropen) -rw-r--r-- 1 bob dba 548 Mar 9 1994 bob.load(rread) -rw-r--r-- 1 bob dba 1449 Mar 9 1994 bob.load(vload)
JCL to compile programs
TSO CLIST driver for some of the assembler programs
VSAM file loader
Single record loader
InfoMange DB dumper