; =====================================================================
; BOOT/Keystone-derived bank-call bridge plus nonblocking INKEY precedent.
; This is platform scaffold, not new Chapter 11 algorithm logic.
; =====================================================================
        ORG     &H0C20

RCS_TOP:
        GST     UA,$6
        PHS     $6
        LDW     $6,SETBK-1
        PHSW    $7
        PST     UA,&H54
        JP      $28

_SYSCAL:
        PST     UA,&H45
        LDW     $6,&H0C10
        ST      $31,($6)
        CAL     RCS
        PST     UA,&H45
        LDW     $6,&H0C10
        LD      $28,3
        ST      $28,($6)
        PST     UA,&H54
        RTN
RCS_END:

        ORG     &H0C50

SYSCAL:
        PST     UA,&H55
        JP      RCS+(_SYSCAL-RCS_TOP)

; BOOT ROM style nonblocking direct scanner/translator.
; BRK follows the established native exit path at 0001h.
        ORG     &H0C60

INKEY:
        CAL     OFFCHK
        LD      $17,$31
        LD      $0,&H4B
IK_LOOP:
        PST     IA,$0
        GRE     KY,$1
        GRE     KY,$1
        DID     $2
        ANCW    $1,$1
        JR      Z,IK_NONE
        SBC     $0,&H41
        JP      Z,&H0001
        LD      $3,$31
IK_BIT:
        BIDW    $2
        JR      C,IK_INDEX
        AD      $3,$30,IK_BIT
IK_INDEX:
        LD      $5,$0
        SB      $5,$30
        BIU     $5
        BIU     $5
        LD      $4,$5
        BIU     $4
        BIU     $4
        SB      $4,$5
        PST     UA,&H44
        PRE     IX,KEYSCAN
        LDD     $0,(IX+$4)
        LDD     $0,(IX+$3)
        PST     UA,&H54
        JR      IK_RETCHK
IK_NONE:
        SB      $0,$30
        JR      LNZ,IK_LOOP
        LD      $0,$31
IK_RETCHK:
        AN      $0,$0
        JR      Z,IK_RET
        LD      $17,$30
IK_RET:
        LDW     $15,WORK1
        ST      $0,($15)
        RTN