for 63k system with 9 sector bios (1 k extra)
sboot64 must be asm with extra=true

dd if=sboot64.bin bs=128 count=1 of=IBM3740.dsk
dd if=1cpm63.bin bs=128 skip=1 count=42 of=IBM3740.dsk
dd if=bios14.bin bs=128 skip=43 count=9 of=IBM3740.dsk

for 64k system with 4 sector bios
sboot64 must be asm with extra=false
use CBIOS

dd if=sboot64.bin bs=128 count=1 of=IBM3740.dsk
dd if=cpm64.bin bs=128 skip=1 count=42 of=IBM3740.dsk
dd if=cbios14.bin bs=128 skip=43 count=9 of=IBM3740.dsk
