Commodore Plus 4 - Page 361

The Disk Drive 349
Line-by-Line Explanation
10 Dimension array to hold directory sector data.
20 Create a string of 16 shifted spaces.
30 Clear the screen and skip a line.
40-50 Print messages to user.
60 Wait for user to hit a key.
70 Print message to user.
80 Open the disk command channel, and initialize the disk.
90 Check for disk errors.
100 Get file name to unscratch.
110 Pad with shifted spaces.
120 Print message to user.
130 Open direct-access channel to disk drive.
140 Check for disk errors.
150 T is the current track; S is the current sector.
160 Read a directory sector into the disk buffer.
170 Check for disk errors.
180 Count the bytes from the disk buffer.
190 Get a byte.
200 Go on to the next byte.
210 F is the current file entry.
220 B is the base address for the current file name entry; start FF$ as a
null string.
230 I counts the bytes in the file name.
240 Concatenate each file name byte to FF$.
250 If FF$ is the file sought, go to line 300.
260 Add 1 to file count. If below 8 (not done with this sector), go on to
the next file entry.
270 Get the next directory track. If zero, then there are no more sectors,
so the file name was not found.
280 Get the next directory sector and return to line 160.