For now we just need something very simple for Getmain, Freemain and Abend processing. This code will need to be updated but this will allow us to IPL and do some initial testing.
000000 1 TXXGMAIN CSECT ,
00000 2 USING TXXGMAIN,R15
3 *
000000 5410 F030 00030 4 N R1,=A(X'00FFFFFF') CLEAN UP LENGTH
000004 4110 1007 00007 5 LA R1,7(,R1) ROUND UP TO DOUBLE WORD
000008 5410 F034 00034 6 N R1,=A(X'00FFFFF8')
7 *
00000C 5800 F01C 0001C 8 L R0,COREPTR
000010 1B01 9 SR R0,R1
000012 1810 10 LR R1,R0
000014 5010 F01C 0001C 11 ST R1,COREPTR
000018 1FFF 12 SLR R15,R15
00001A 07FE 13 BR R14
14 *
00001C 00100000 16 COREPTR DC A(1024*1024) 1M
Getmain will round the requested length up to a double word value. For now we will simply start at the 1 Meg mark and work backwards. No attempt will be made to reuse memory when it is released via a Freemain. This will allow us to IPL and run for a little while before we eventually start overlaying or Nucleus code.
000000 1 TXXFMAIN CSECT ,
00000 2 USING TXXFMAIN,R15
000000 07FE 3 BR R14 RETURN TO CALLER
The Freemain routine is very simple. It simply returns to the caller.
000000 1 TXXABEND CSECT ,
00000 2 USING TXXABEND,R15
000000 8200 F008 00008 3 LPSW ERRPSW
000008 4 DS 0D
000008 00020000000BAD01 5 ERRPSW DC AL1(0,2,0,0),A(X'BAD01')
The Abend routine will simply load a wait state PSW.
Although the code in these routines is not very robust it now gives us everything we need to link edit the Nucleus and IPL.