

 lib environment
 sttl Null Device Driver
 pag
 name nulldrvr
 global nodev,nuldev,nuldrd,nuldwr

*
* Null and no device calls
*

nodev lda #EBDEV set error
 sta uerror
nuldev rts return


*
* null read driver
*

nuldrd ldd #0 set eof status
 std urglst+UD
 rts return

*
* null write driver
*

nuldwr ldd #0 -- set all written
 std uicnt return as write count
 rts return
