LOAD does not load complete program

[dimitrit]

LOAD fails to load the complete program if a program line number in hex includes 0x1A, for example:

1000 PRINT "HELLO"
1050 PRINT "GOODBYE"

In this example line 1050 (0x041A) will fail to load.

[dimitrit]

Issue is caused by the 'end of file' detection incorrectly identifying the 0x1A in the line number as EOF.

[stefanobaldo]

I have opened #6 with a fix for this.

The copy loop stops testing for the marker — it cannot tell a line number's
low half from the terminator, and telling them apart needs the previous line
number, which the loop cannot carry across the BDOS call between records. The
end of the program is found afterwards by walking the lines: 1ah is the
marker only at a line's first byte, and only when the two bytes there do not
read as a line number greater than the one before it.

One thing worth knowing separately from the fix: examples/tictac.tba is
complete, all 117 lines of it. It only ever loaded as 94, which is why the
game stops at line 1020 with HOW? on a GOTO 1050 that was never brought
into memory. Nothing needs regenerating — it loads whole and plays with the
change.

Measured before and after on the CP/M build, including your example above and
a program with a line 26. Details and the residual case are in the pull
request.