DIM #n
DIM #n TO [%]var

This command returns the size (in characters or bytes) of stream n. Whatever applies to the RETURN #...TO variant of POINT # applies to the DIM #...TO as well. Variable var stores the size of the stream. As with RETURN #...TO above, var can be an integer variable in which case the same warning as with the previous section applies.

GO TO #n, [%]pos

This command sets the current position of stream n to position pos. Let's see how the previous three commands all tie together by experimenting with browser.cfg:

10 OPEN #4,"/nextzxos/browser
   .cfg"
20 REM "i>" is optional since
   the filename is longer
   than 1 character
30 DIM #4 TO %a: REM Get
   filesize and put it in %a
40 RETURN #4 TO %b: REM Get
   current location and put
   it in %b
50 PRINT "You're in byte: ";
   %b ; " of "; %a
60 GO TO #4, %a/2: REM Move
   to the middle of the file
70 RETURN #4 TO %b: REM Get
   current location and put
   it in %b
80 PRINT "Now, you're in
   byte: "; %b ; " of "; %a
90 CLOSE #4

NEXT #n TO [%]var

This command gets the next character of input from stream n. As with POINT # and DIM #, if used with the TO modifier it also stores it in the variable var. If used on the standard k channel, this is similar to the INKEY$ function, except that it always waits for the next character to become available (ie on the k channel, it waits for a keypress). Using an integer variable here, is safe as the command gets one character at a time ergo one byte so its value will never exceed 255.

You can use this command instead of INPUT # on all channels that accept input otherwise they're very much identical in function.

Try this little program which will turn your ZX Spectrum Next into a typewriter:

10 NEXT #0 TO x
20 PRINT CHR$(x);
30 GO TO 10

Alternatively you could change line 10 to: