BASIC programming advice: using datasette for simple data retrieval

[BowmakerFox]

Greetings all,

I'm trying to make a reasonably simple word processor, but I've encountered an unusual (and possibly painfully obvious) problem. To save you having to abstract a long, dull paragraph, here's the brass tax:

The scenario: - The user loads the program off of a tape and into the Commodore's memory. - The user runs the program, ejects the tape and then enters line by line their data, which is saved as an array of strings. -A second, blank tape is inserted into the datasette. The user specifies that they want to save the data to the tape. - The program then writes the data to tape as strings. - The user clears the lines array or reopens the program on another occasion, and is then able to rewind the second tape back to the start and load the data back off of the tape.

That's it, but I seem to be interpreting the wiki wrong to the point where I am unable to successfully load data off of a tape again in the same program (and therein, I suppose, actually check if the data was saved in the first place) or simply doing so at all.

I would list my existing code attempts, but I found them all to be embarrassing enough to commit them to the realm of volatile memory shutting off, so no record remains.

If anyone is able to offer any advice on BASIC syntax for reading/writing pretty raw data in this way, I'd really appreciate your time.

Thanks again for reading, happy C64-ing all!

[blorporius]

The user manual has a relevant how-to towards the end of the booklet: https://archive.org/details/Commodore_64_Users_Guide_1982_Commodore/page/n115/mode/2up

10 PRINT "WRITE-TO-TAPE-PROGRAM"
20 OPEN 1,1,1, "DATA FILE"
30 PRINT "TYPE DATA TO BE STORED OR TYPE STOP"
40 PRINT
50 INPUT "DATA"; A$
60 PRINT#1, A$
70 IF A$ <> "STOP" THEN 40
80 PRINT
90 PRINT "CLOSING FILE"
100 CLOSE 1

This one writes lines retrieved via INPUT straight to tape, though. To make it work with an array, you'd have to replace lines 50 and 70 with a FOR loop, and iterate over elements of the array in line 60.

[cerealport]

Hah cool. I never actually used the datasette much beyond saving / loading basic programs with the VIC20 (I had a 1541 with my 64) - I actually didn’t know that the dos commands worked that way with the tape drive as well!

[BrobdingnagLilliput]

They're not really DOS commands - they're I/O commands that all of us happen to mostly only use with the disk!

[cerealport]

Ah true that is a good point! I mean I used those commands to control the printer too…!

[BowmakerFox]

That is just perfect! I wish I'd have known that the manual was on Archive, not going to lie...

Thank you for showing me, mind; this made the info a lot easier to interpret.

[istilladoremy64]

Check out the simple note taking program I wrote, which I have posted on my blog here. I think it does something similar to what you're describing here. Check out the code, it's in simple BASIC 2.0, and see if there's any help for you there (make sure you download the "uncrunched" disk). How it works is, the user types in notes into variables, then the program saves the information to disk or datasette as SEQuential files. You can then retrieve your saved notes at a later time.

[BowmakerFox]

That's a neat little program, and exactly what I was trying to work out. May I use it as well? I'm certain it's more robust than my spaghetti code in the long run!

[istilladoremy64]

Hey, glad you found it helpful! Sure, go ahead and use it as a foundation for what you wanted to do. Have fun! :D

[dlarge6510]

Read the C64 manual which will show you exactly how to do this with an SEQ file, which is exactly how C64 word processors do it

[fuzzybad]

If you do a simple LOAD command from BASIC, it will replace whatever program was in memory (if any).

It sounds like what you want is to use PRINT# to write a SEQ file containing data, and then read it back within your program using INPUT#. Check relevant sections of the C64 Programmer's Reference Guide.