[Coco] RANDOM ACCESS FILES IN DISK BASIC

[coco at jechar.ca]

Hi Trying to figure out how to open a random access file in disk basic.

Tried this code

10 DIR 0
11 PRINT "FILE NAME"
12 INPUT F$
14 F$=F$+":0"
16 PRINT F$
20 OPEN "D",X,F$,1

The idea is that the program would be ran from disk 1 but would use data
files on disk 0.

This program gives me an error, the file name was TEST it is a binary
file I want to grab each byte and then display the hex value should be
easy enough but I get an error in line 20.

What have I done wrong ?

Charlie