( AVR Programmer, load range 160-163. doc/avr.txt )
( page size in words, 64 is default on atmega328P )
CREATE aspfpgsz 64 ,
VARIABLE aspprevx
: _x ( a -- b ) DUP aspprevx ! (spix) ;
: _xc ( a -- b ) DUP (spix) ( a b )
    DUP aspprevx @ = NOT IF ABORT" AVR err" THEN ( a b )
    SWAP aspprevx ! ( b ) ;
: _cmd ( b4 b3 b2 b1 -- r4 ) _xc DROP _xc DROP _xc DROP _x ;
: asprdy ( -- ) BEGIN 0 0 0 0xf0 _cmd 1 AND NOT UNTIL ;
: asp$ ( spidevid -- )
    ( RESET pulse ) DUP (spie) 0 (spie) (spie)
    ( wait >20ms ) 220 TICKS
    ( enable prog ) 0xac (spix) DROP
    0x53 _x DROP 0 _xc DROP 0 _x DROP ;
: asperase 0 0 0x80 0xac _cmd asprdy ;