Subject: Long BASIC format

From: "Michael Zapf" <[email-masked]>
Date: Mon, 18 Apr 2011 12:41:08 -0000

Hi there,

does anybody know something about the file format INT/VAR 254 used for long Extended Basic programs?

Seems to me as if the first record always contains a 10 byte header, probably containing memory pointers. I'm not sure about the second header; whether it starts with the Exbasic program or also has a header.

It's difficult to find out by experiment since Exbasic automatically uses the format when programs become too long to fit into the VDP space.

Michael

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From: "Tursi" <[email-masked]>
Date: Mon, 18 Apr 2011 10:09:53 -0700

Yes, I went through all the experimentation for XB IV254 files. You can 
easily force its use by making the VDP space smaller. I wanted to use it for 
my Extended BASIC Bitmap Picture tool, which needed to be able to fix up the 
pointers and load various sized programs.

This is what I came up with:

XB Save file format, first record is 10 bytes long (and ends the sector). 
This does NOT apply to PROGRAM image saves. Note if a program is small 
enough, no matter what you did, it is relocated when saved as a VRAM image 
and the changes are lost.

ABCD -- header tag - this is a constant.
xxxx -- start of line number table (this is the value that is stored at 
 >8330)
xxxx -- end of line number table (this is the value that is stored at >8332)
xxxx -- XOR of start and end line number table values (sanity check)
FFE7 -- top of RAM (this is the value that is stored at >8384)

-----Original Message----- 
From: Michael Zapf
Sent: Monday, April 18, 2011 5:41 AM
To: [email-masked]
Subject: [TI994A] Long BASIC format

Hi there,

does anybody know something about the file format INT/VAR 254 used for long 
Extended Basic programs?

Seems to me as if the first record always contains a 10 byte header, 
probably containing memory pointers. I'm not sure about the second header; 
whether it starts with the Exbasic program or also has a header.

It's difficult to find out by experiment since Exbasic automatically uses 
the format when programs become too long to fit into the VDP space.

Michael

------------------------------------

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From: "Michael Zapf" <[email-masked]>
Date: Mon, 18 Apr 2011 20:18:40 -0000

Hi Tursi,

> FFE7 -- top of RAM (this is the value that is stored at >8384)

nice, thanks - seems to work. My Java-based TIImageTool can now list those BASIC programs as well.

BTW, the check value is negated for ExBasic-protected files.

Michael