AUTOBOOT FOR CASSETTES
There was a rather technical article in ANTIC, June 1983, titled "Autoboot for BASIC." I contacted Eric Verheiden, the author, and asked him to customize his program for creating AUTORUN.SYS files on a cassette. This is the result of that collaboration. The BASIC program listed in this article contains the DATA statements you will need to put this routine in your own computer.
AUTOCAS loads a small machine program into Page Six of your computer's memory. Once the routine is loaded, all you do is enter the command X = USR(1536) to invoke it. AUTOCAS will then "beep" at you to remind you to put a cassette in your 410/1010 Program Recorder. When you have a tape properly put in the recorder, press the [RETURN] key and AUTOCAS will write a small program onto your tape. Now, simply CLOAD your favorite BASIC program and CSAVE it on the AUTOCAS tape. You will then have a copy of your BASIC program that will Ioad just like any other boot tape.
That is all you really need to know to use AUTOCAS, but you might like to understand a little bit of how it does its tricks. Essentially, AUTOCAS writes a small machine-language program onto your cassette. The small program loads like any other boot file would, then it executes a forced read on the screen of two BASIC commands: CLOAD and RUN. That's it. This is very similar to what a disk-based AUTORUN.SYS program normally does for a disk file.
It is possible to make one of these "AUTO" routines do a lot of other things, but that would require some knowledge of 6502 assembly language and source code for AUTOCAS. I am only giving you the BASIC POKE version of AUTOCAS in this article.
USER'S GUIDE TO AUTOCAS
Here is a step-by-step explanation of how to use this program. I will assume that you have already typed AUTOCAS into your computer and CSAVE'd it to a cassette.
STEP 1. Make sure the BASIC cartridge is in your computer and that ALL peripherals are turned OFF. (AUTOCAS will not work properly if the 850 Interface Module or a disk drive is turned ON.)
STEP 2. Put your cassette copy of AUTOCAS in your recorder and press the [PLAY] button.
STEP 3. Enter CLOAD and, when the computer beeps, press the [RETURN] key. Your copy of AUTOCAS will then load like any normal BASIC program. When it has loaded, type RUN and press the [RETURN] key. A title page will come up on the screen. You will be asked to press [START] when you are ready to write the AUTO routine to the cassette.
STEP 4. Insert a blank tape into your recorder and completely rewind the tape. Press the [RECORD] and [PLAY] buttons on the recorder. Now press the [START] key and AUTOCAS will write a short program on the tape.
STEP 5. You will now see a new message on the screen. It will prompt you to press the [START] key to CLOAD your own program. That will be the program you want to make into an auto-load program. Remove the first tape, without rewinding it, and insert your favorite program. Press the [START] key. The screen will clear and your program will start loading. This process will erase the BASIC portion of AUTOCAS from memory.
STEP 6. You can now repeat the process for other BASIC programs without loading the original AUTOCAS program back in your computer because the important machine language routine is still in the computer. CLOAD another program and enter the direct command X = USR(1536). You will hear the familiar double beep. When you press the [RETURN] key the little auto-load routine will be written out to tape again. You can then CSAVE the second BASIC program to make it an auto-load program too. AUTOCAS will not autoload more than one program. However, your BASIC program can always load another program.
Listing: AUTOCAS.BAS Download