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WIP Modern Debugger for the OG PS1

SjefCoder

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Hi all,
Everyone inevitably remembers how you could boot a Yaroze disc and debug your code.
However, that software is very ancient by today's standards.
Accordingly, I set out to develop a new boot disc that allow you to connect with GDB and debug your code on retail hardware.
Hopefully this can lower the bar for PSX development and slowly make the ancient (unaffordable) hardware obsolete for development purposes.

The files can be downloaded from here:


A video of me narrating and putting things into action can be seen here:

 
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Dedok179

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It works with PSY-Q? What interface is used to connect the pc and console?
 

Trimesh

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Just out of interest, where does this load the debugger stub and can you change it? I have a couple of consoles that I've modified to support 8MB of RAM, and it would be nice to be able to load the debugger up at the top of memory so the standard 2MB on the retail consoles is completely clean.
 
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SjefCoder

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Just out of interest, where does this load the debugger stub and can you change it? I have a couple of consoles that I've modified to support 8MB of RAM, and it would be nice to be able to load the debugger up at the top of memory so the standard 2MB on the retail consoles is completely clean.
Haha, help me with procuring an 8mb console, and you may load the debugger up in my head :p
 

SjefCoder

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Ok, in all seriousness, would love to test this functionality. Had looked into the 8mb upgrade (as it would solidify my ambition to make the dtl-h2000 obsolete), but I neither have the chips nor the air-soldering skills :(
 

Trimesh

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Ok, in all seriousness, would love to test this functionality. Had looked into the 8mb upgrade (as it would solidify my ambition to make the dtl-h2000 obsolete), but I neither have the chips nor the air-soldering skills :(

Well, I can send you the chips, but you will need to find someone to install them...
 
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SjefCoder

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So here, is a small update. I have finally been able to build the loader, so the debug stub needs not be compiled inside the software to be tested. Rather, the software to be tested can be uploaded on the spot (just like the Yaroze boot disc).
The screenshot shows a piece of hello world code compiled with n00bsdk being debugged on a Mac via gdb. I added a gdb layout config as it is more robust and responsive than vsCode, and also mimics the old Sony Dos debuggers.

gdbpsx.png
 

SjefCoder

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Status update.
I have to thank Trimesh. He was gracious enough to donate one of his boards, so I can experiment and test on a working 8mb retail console.
Meanwhile I am trying to abstract away the interface into a proxy like setup, so that it becomes possible to have different connections to the PSX (i.e. not only serial, but also much faster options like the Raspberry PI or CPLD (options, whose credits go to: DanHansbro)).

Well, I can send you the chips, but you will need to find someone to install them...
 

Trimesh

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Cool - glad you got it and rather surprised it arrived so quickly seeing as how messed up shipping has been recently.

Just for reference, the board was originally from a SCPH-5500, so it has a Japanese mechacon and outputs NTSC. Since it only has the original NTSC oscillator, it will produce an out of spec composite signal in PAL mode which will probably display in black and white (although RGB still works if you have a suitable cable). It will however boot discs from any region - there is a PSNee installed and the original Japanese boot ROM (which rejects non-Japanese discs) has been replaced with a US one.

Have fun!
 
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SjefCoder

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Here is a video demo. I have finally achieved a level of stability and speed that I feel comfortable with. Hopefully I can soon release the first alpha. In the video you can see me print out memory contents, set breakpoints, and step through code.

 

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