: $f EDPOS @ PREVPOS @ 2DUP = IF 2DROP EXIT THEN
    2DUP > IF DUP pos! SWAP THEN
    ( p1 p2, p1 < p2 ) OVER - 64 MIN ( pos len ) FBUF _zbuf
    SWAP _cpos FBUF ( len src dst ) ROT MOVE ;
: $R ( replace mode )
    mode! 'R' EMIT
    BEGIN setpos KEY DUP BS? IF -1 EDPOS +! DROP 0 THEN
        DUP 0x20 >= IF
        DUP EMIT EDPOS @ _cpos C! 1 EDPOS +! BLK!! 0
    THEN UNTIL mode! SPC contents ;
: $O EDPOS @ 0x3c0 ( 15 * 64 ) >= IF EXIT THEN
    _U EDPOS @ 0x3c0 AND DUP pos! _cpos _zbuf BLK!! contents ;
: $o EDPOS @ 64 < IF EXIT THEN EDPOS @ 64 + EDPOS ! $O ;
: $D $H 64 icpy
    acc@ 0 DO 16 EDPOS @ 64 / DO I _mvln- LOOP LOOP
    BLK!! contents ;