*= $2000
memsetup
 lda $d301  ; PORTB
 ora #$02   ; disable BASIC (XL/XE only)
 sta $d301
 lda #$80
 sta $6a    ; RAMTOP
 sta $02e6  ; MEMTOP high
 lda #0
 sta $02e5  ; MEMTOP low
 sta $022f  ; SDMCTL (turn off screen)
 lda $14    ; RTCLOK+2
loop
 cmp $14    ; wait until next frame
 beq loop
 rts

 *= $02e2  ; INITAD
 .word memsetup