Hi all;

I picked up a TI 84+SE so I could play around with Z80 assembler. I dont have a compiler or anything, so I write code on paper and converted it to hex to key into the calculator. I dont plan on writing anything big, so this works OK. Here's a program I wrote that displays 48 bytes of memory starting at address 9d95h, which displays this program. I tried to dump memory of some bcalls just to see what they looked like, but the results don't look like what I expected. Bcalls look like they are a table of 3 byte long calls or jumps to other addresses, but what I saw looked like ordinary code. Does that mean that the bcall code gets swapped in and out of the address where I think it is. If that's true, how do I swap areas of memory or is that too complicated. I spent the last few days looking thru the forum for this information, but I didn't find anything.

program to dump 48 bytes of memory.
current starting dump address is 9d95, which shows this program.
change the starting address to show different memory areas.

C3 b3 9d
4F
CD a1 9d
79
CD a5 9d
C9
1F
1F
1F
1F
E6 0F
F6 30
FE 3A
38 02
C6 07
EF 04 45
C9
21 95 9d ----->9d95, starting address to dump, low, high byte
06 30 ----->30, hex number of bytes to show (48 decimal)
7E
CD 98 9d
23
10 f9
C9

Thanks
Dave

It would be nice if you could give us the z80 version of the hex code.

Umm... It's exactly the same. Just throw it into a dissasembler if your prefer.

Dave, to answer your question, you may want to look at the structure of the vector table for bcalls, available here:
http://wikiti.brandonw.net/index.php?title=83Plus:OS:ROMPage1B
In addition, you may want to explore how bcalls work. When you use "bcall(_something)", it's really just a macro.
http://wikiti.brandonw.net/index.php?title=83Plus:OS:How_BCALLs_work

You will need to work with memory mapping, which can be done by simply using the 'out' and 'in' instructions. Here's some more info:
http://wikiti.brandonw.net/index.php?title=83Plus:Ports:06
http://wikiti.brandonw.net/index.php?title=83Plus:Memory_Mapping
So, to swap in the bcall vector table for lookup:

Code:

tmwilliamlin168;

Here's the code that I created the hex values from.


Code:



MateoConLechuga;

Thanks for the information. I'll look thru it and see if it makes sense to me.

MateoConLechuga;

I looked thru the links you posted. I think that's a little over my head right now. I'll keep reading thru it and try to understand what's happening. I crash my calculator a lot because I don't convert the code to hex correctly some times. Swapping pages in and out probably adds more complexity to my conversion.

Please use an assembler to avoid the headache of mis-typing code. In addition, an emulator will let you save time debugging ASM, because you can keep testing new versions of your code without having to spend the time re-typing the program each time. Since you have a TI-84 Plus Silver Edition, you can use to dump a ROM image from your calculator, then use [url=http://sc.cemetech.net]SourceCoder 3 to both assemble and test your programs in your browser (it includes an editor, assembler, and emulator).

Is there any disassembler that actually treats the 2 bytes after a bcall parameters instead of commands?
For example:

Code:

A disassembler will treat the 01 and 45 as commands

Um, yes. RunerBot does a nice job. Copy and paste this into the sidebar chat window.


Code:


Oh, and here's Kerm's post in case you missed it: (Along with fixed links )

Runerbot can only handle short hex codes.

If you have access to an assembler, it really does make it easier, but I understand sometimes people don't have access to a computer or the software or hardware required for sending programs.


Now, to answer OP and make some clarifications. First, bcalls have an address that points to a spot in an look-up table. For example, _PutC is 4504h. On my calculator, this means that I need to load page 7B into membank1, and then look at the three bytes at 4504h. On my calc, these three bytes are "4C5B01" so the actual code for _PutC is located on page 01 at address 5B4Ch and starts with "F5E5FED62012".

By the way, if it helps to read that last code, char D6 is a newline, which jumps down a line and displays a colon.

Depending on the calc model, the bcalls may be located on page 3B and 3F or 1B and 1F.


Now here is my take on your hexdump program:

Code:


But hte following should make it all much easier to dump bcalls. Where you would do EF0445 for bcall(_PutC), use 210445 at the start of this program and it will search for the bcall code and dump it.

Code:

Xeda112358; Thanks for the code and explanation. I just got my ROM loaded into the SouceCoder 3 emulator and I was going to add the code for the bank swapping into my original code and try it on the emulator. You saved me some time and also made a better version.

Xeda112358 Here's the dump of PutC using the address and page you show above. 5b4c is really 1b4c in page 1.


Code: