collapseos/blk/286

lblnext BSET PC ORG @ 0x1b + ! ( next )
( This routine is jumped to at the end of every word. In it,
  we jump to current IP, but we also take care of increasing
  it by 2 before jumping. )
	( Before we continue: are stacks within bounds? )
    ( PS ) HL PS_ADDR LDdn,
    SP SUBHLd,
    JRC, lblofl BWR ( abortUnderflow-B285 )
    ( RS ) IX PUSH, HL POP,
    DE RS_ADDR LDdn,
    DE SUBHLd,
    JRC, lblofl BWR ( IX < RS_ADDR? abortUnderflow-B285 )
    LDA(BC), E A LDrr, BC INCd,
    LDA(BC), D A LDrr, BC INCd,
    ( continue to execute )