BAL: IBM 360 Assembly Language

BAL (always spelled out: BEE-AY-EL) stands for Basic Assembly Language. This is the assembly language for the IBM 360/370/390 series of computers. One cannot program in assembly language without using some operating-system-specific coding. If nothing else, one must obey the proper linkage conventions. It is also necessary to interface with the OS for I/O operations, and this is usually done directly.

Like most of the IBM 360 languages, BAL is card oriented. Labels must start in column 1. Statements may not extend beyond column 71, unless they are continued to the next line. One continues a statement by placing an X in column 72.

Since the code contains OS-specific stuff anyway, I also included the JCL necessary to compile, link, and run the code. The OS-specific stuff is for MVS 3.8, as is the JCL. This code compiles and runs on the Hercules emulator running Turnkey MVS 3.8j.

//ASMFCLG JOB CLASS=A,MSGCLASS=A,MSGLEVEL=(1,1),REGION=128K //HELLO EXEC ASMFCLG //ASM.SYSUT1 DD UNIT=SYSDA //ASM.SYSUT2 DD UNIT=SYSDA //ASM.SYSUT3 DD UNIT=SYSDA //ASM.SYSPUNCH DD DUMMY //ASM.SYSGO DD UNIT=SYSDA //ASM.SYSIN DD * *0 1 2 3 4 5 6 7 *2345678901234567890123456789012345678901234567890123456789012345678901 * ////////////////////////////////////////////////////////// * // Name: Peter M. Maurer * // Program: Sieve of Eratosthenes * // Due: Never * // Language: BAL -- IBM 360 Assembly Language * ////////////////////////////////////////////////////////// * SIEVEE CSECT STM 14,12,12(13) Save registers LR 12,15 Establish base register USING SIEVEE,12 ST 13,MYSAVE+4 Link save area for I/O operations LA 11,MYSAVE ST 11,8(0,13) LR 13,11 SR 2,2 Master loop index 0-1000 LA 3,CAND Pointer to array MVI CAND,0 Flag off 0 & 1 MVI CAND+1,0 LA 7,CAND Pointer past end of array A 7,=F'1000' L1 C 2,=F'1000' Master loop test BNL EL1 CLI 0(3),0 Is this flagged off? BNE PRIME No, jump (Must be prime) LA 3,1(0,3) Incr ptr & ctr LA 2,1(0,2) B L1 To Master loop test PRIME EQU * Found a Prime LR 6,3 2 is stride 3 is array ptr AR 6,2 PLOOP CR 6,7 Past end of array? BNL EPLOOP MVI 0(6),0 Flag off AR 6,2 Next stride B PLOOP EPLOOP EQU * LA 3,1(0,3) Next candidate LA 2,1(0,2) B L1 End of main loop EL1 EQU * *Printing is a chore OPEN (OUTDCB,(OUTPUT)) LA 2,CAND SR 3,3 L4 C 3,=F'1000' Print loop BE RETURN Done printing CLI 0(2),0 BE NEXT Not prime skip CVD 3,PN Print index # UNPK VAL,PN+6(2) OI VAL+2,X'F0' PUT OUTDCB,MSG NEXT LA 3,1(0,3) Next candidate LA 2,1(0,2) B L4 To print loop RETURN CLOSE (OUTDCB) L 13,4(13) Back out save area LM 14,12,12(13) Restore regs SR 15,15 Return code 0 BR 14 Return MYSAVE DC 18F'0' MSG DC C' ' Printer control character VAL DS CL3 DC C' is prime' DC 129C' ' PN DS D OUTDCB DCB DSORG=PS,LRECL=133,RECFM=F,MACRF=PM,DDNAME=SYSOUT CAND DC 1000C'1' END /* //GO.SYSOUT DD SYSOUT=A //

Click Here for the actual code.