VTL-2 - How to use?

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B Hill

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Mar 23, 2024, 3:59:31 AMMar 23
to PAL 6502 computer

Hi all,
I am very new to this type of computing. I have been reading through threads and websites for a while and can't figure out how to use VTL-2.

I have the version for PAL-1 without memory expansion, from here.

I have serial going and can upload software. I successfully ran a few example programs.

I think that the page says to load at 0FB0, so I type 0FB0, hit space bar, and then G.. and nothing happens.

What am I missing?
Thank you.

Neil Andretti

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Mar 23, 2024, 4:30:30 AMMar 23
to PAL 6502 computer

B Hill

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Mar 23, 2024, 2:04:58 PMMar 23
to PAL 6502 computer
Unless I am missing something, that has useful info on how to use the language, but doesn't help me. I am not sure how to get to the point where I can start using the language. It seems like I should be getting an "OK" prompt when I load it.

B Hill

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Mar 23, 2024, 2:48:44 PMMar 23
to PAL 6502 computer
Very simple user error, as I knew it would be. I had only pasted 0FB0 into the terminal, which did not work. I needed to type it...

Jim McClanahan

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Mar 23, 2024, 8:27:56 PMMar 23
to PAL 6502 computer
It shouldn't matter, but one thing I'd do is make sure to load $00F1 with $00 so decimal mode is cleared when the program starts. (The program clears decimal mode a few instructions in, but strange things happen sometimes.)

A couple of quick things to check. I'd zero out $0FB0 (and two or three more bytes) and also put a $FF in $00CC and $00CD. Then I'd load the program.

When you go back to $0FB0 after loading VTL, you should see an $A9 (LDA) stored there. If you don't then something isn't loading right.

If you see $A9, then I'd use the G command like you have been. Once it locks up, reset and look at what is stored at $00CC. If it is still the $FF (instead of having been changed to $00) then that would mean the initialization routine (which is what you are supposed to be starting when you Go at $0FB0) isn't running.

All of that should tell you if things are even getting started. You can jump straight to the intro message routine also. It looks like that is at $13CB in this version of things. If you point the monitor at $13CB you should see a $A2. If you Go there, it should print the '6502 VTL-02C for the PAL-1' message and then jump back to the monitor (I think, it might hang after the message).

Hopefully as you work through some of that, you'll get some clues as to where things are going wrong.

Thanks,
Jim W4JBM

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Jim McClanahan

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Mar 24, 2024, 1:40:18 PMMar 24
to B Hill, PAL 6502 computer
One thing I do on a lot of the punch format files I upload to the PAL is to add a few lines to help me avoid mistakes and to keep from having to remember the details every time. I usually add a line in punch tape loader format that changes the condition register preload so I don't end up in decimal mode accidentally and a line at the end that sets the monitor to the start address. (I don't actually have the file enter the "G" to run things, but I know that everything is good to go after I load it and that is all I have to press.)

The only thing I have to be careful of is making sure I run unix2dos because I'm editing it on a linux box and the monitor needs the carriage returns instead (not the line feeds that linux uses to mark the end of line by default).

Thanks,
Jim W4JBM

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GN Liu

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Mar 25, 2024, 1:22:43 AMMar 25
to PAL 6502 computer
fw, B Hill
 
from B Hill,
It seems like "my thank" you comment got deleted for some reason. I appreciate your help, and all of the resources you have online.

(this message also deleted for no reason..... :S)

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