Once you have some sequential data in a file on your disk, you can write a program to read it back. How this is done, varies between different Commodore machines, and can be quite tricky. On the C128, it is as easy as writing the data. You have to remember the structure of the data you were writing – in my case one string, one integer and one string.

This is a new program (clear any existing program by typing NEW), and it is assumed that you have your floppy with the data you created in the earlier post.

Use OPEN to open a file, but this time, specify that you want to READ the sequential file TEST.DAT.

10 OPEN 1, 8, 2, "TEST.DAT,SEQ,READ"

Then, use INPUT# to read each stored record. Just remember the data types. PRINT# supports writing multiple records in one call, and INPUT# supports multiple reads. So instead of writing three lines, I can read three records in one line, like so:

20 INPUT#1, A$, B, C$

Use CLOSE to close the file.

30 CLOSE 1

These line will display the file content on screen:

40 PRINT A$
50 PRINT B
60 PRINT C$

And if everything is correct, you will now se this:

ONE STRING
 5
ANOTHER STRING

(The commands I use are available Commodore Basic 4.0 on Commodore PET, but I run Commodore Basic 7 on a C128.)

HEADER "MY DISK", I44, D0

(Formatting a disk takes a while.)

If you are running a virtual Commodore 128 in VICE, click File, Attach disk image, Drive 8. Create a d64 image file and attach that image. To create the file, enter a desired filename, like test.d64, provide a name, click Create Image, then click Attach.

(The commands I use are available Commodore Basic 4.0 on Commodore PET, but I run Commodore Basic 7 on a C128.)

Your disk is now inserted and completely empty. You can check the content using the DIRECTORY command.

As a Commodore user, you know that you sometimes have to refer to your disk drive using its drive number (the first disk drive is 0) and sometimes you have to use the device number (the first disk drive is 8). The OPEN command operates on any device, therefore a device number is required in this case. The first parameter is the logical file number (just a number that identifies the file), the second is the device number (8). The third argument is a channel number – enter 2. Then, in one single string argument, you type in the file name, the file type and the file mode. I want to create a file called TEST.DAT as a sequential file and I want to write to it, so I my string holds “TEST.DAT,SEQ,WRITE”.

10 OPEN 1, 8, 2, "TEST.DAT,SEQ,WRITE"

To fill your file with data, use the PRINT# command. Anything goes here. This will print one string, one integer, and then yet another string. You provide your logical file number so that PRINT# knows what file you are targeting.

20 PRINT#1, "ONE STRING"
30 PRINT#1, 5
40 PRINT#1, "ANOTHER STRING"

If you like, more data can be added in one line.
When you are done writing, close the file using the CLOSE command. Again, provide your logical file number.

50 CLOSE 1

After running this program, you should have a small sequential file called TEST.DAT on your disk. If any disk error occurred, the lamp on your drive is flashing now – it shouldn’t do that.

Continued here.

• VoF’s diskussionsforum
• Skeptikerpodden
• Sweskep.com

Om du har inlägg eller länkar som du vill spara, ska det göras före juni 2012. Fram till 2012 går det bra att posta nya inlägg, såvida du inte registrerat från någon publik e-posttjänst (typ Hotmail eller gMail),

10 GRAPHIC 1, 1
20 FOR A = 1 TO 100
30 DRAW 1, RND(1) * 320, RND(1) * 200
40 NEXT A

When the program is run, the text is hidden, so to retain the text cursor, just type GRAPHIC 0 and hit Enter. If you like, you can add this to your program.

The Commodore 64 does not provide any API for graphics, so on the C64 this task is accomplished by manipulating bits in a memory area. You can jump to graphics mode by setting the bit 6 on byte 53265 to 1 and return to text mode by setting it to 0. While plotting, you must make sure you know how to handle bit patterns. The screen area can be located at 8192 if we set a flag for this (bit 4 at byte 53272), like so:

10 POKE 53272, PEEK(53272) OR 8

The screen consist of 8000 bytes, so in this case from 8192 to 9191. Then, enter graphics mode:

20 POKE 53265, PEEK(53265) OR 32

Now we don’t have the service to get a clean color map (that is Commodore 128 luxury), so random boxes (8×8 pixels) will have strange colors. No worries, this is expected.

Finally, these lines of code will draw a few horizontal lines in the upper left 8×8 pixel area:

30 POKE 8192, 255
40 POKE 8193, 0
50 POKE 8194, 255
60 POKE 8195, 0
70 POKE 8196, 255
80 POKE 8197, 0
90 POKE 8198, 255
100 POKE 8199, 0

When the program has run, you will not see the text cursor, but to restore everything, type:

POKE 53272, 21
POKE 53265, 27

…and our horizontal lines will be gone and the text cursor is back.

run -p

This displays all running processes together with an ID.

run -k 1234

This will kill process with ID 1234 (careful with this). And finally, to display your defined aliases, type:

run -a

Download run.exe from here.

Now, I can start CDBurnerXP by typing:

run "C:\Program Files (x86)\CDBurnerXP\cdbxpp.exe"

Also, passing arguments to programs are also supported, so this will open the a specified web page in

run "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" http://www.winsoft.se/

This might feel a bit odd, because this command can already be executed from cmd.exe, so what does the run command actually provide?

In the configuration file, you can point out a file that define aliases. The alias file consists of aliases for any phrase you like. By defining an alias for the Firefox path like so:

#DEFINE ff "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"

…you can start Firefox and open a specific address like so:

run ff http://www.winsoft.se/

And of course, you can add another line to your file to create an alias for the URL you want to visit, like so:

#DEFINE ff "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"
#DEFINE winsoft http://www.winsoft.se/

Now, all you need to type to open WinSoft.se in Firefox is:

run ff winsoft

You can also use run to display running programs and close programs. More information and a download link to come.

This clip shows how to use the Commodore 65 in C64 “fast mode”.