alt Hacker NewsReverse Engineering the Prom for the SGI O2
Comments
Awesome work! Enriching the disassembly with known constants and labels is great, great stuff.
As somebody else suggested, try Ghidra's decompiler. It produces very sloppy C code, but still reads faster than assembly most of the time.
Now enriching Ghidra's decompiler output to clean up the C code, that would be a neat trick, and one that Ghidra isn't doing.
I often see superbly restored SGI equipment at VCF and also own a few SGI equipment that I hope to get to some point in my life but I have never seen any interesting new software or usage of these machines other than the stock "cool" demo programs(The file manager, the gears demo and others running at the same time). Is there any actual cool homebrew occuring on these platforms?
The successor to SGI, after several acquisitions and bankruptcies, is Hewlett Packard Enterprise. There's a forum for abandoned HP products.[1] The SGI O2 has been mentioned, but not in recent years.
I for one is awaiting for the world to completely decompile and or reverse engineering the IBM mainframe microcodes for all their machines.
Number 1 because Mainframes without the microcode is sent to the junkyard.
In the PC world this would be known as "BIOS modding".
The first two instructions looked legitimate, but the third looked unlikely to be a real instruction.
Given that the first appears to be a branch, that's not surprising. When disassembling, not following the flow will likely not give you anything meaningful. If the author is reading this: have you tried Ghidra?
That said, this seems a lot simpler than PC BIOSes in structure, as the latter are usually written in a combination of C and Asm (I can see why no one wanted to write MIPS Asm) and are self-extracting compressed archives.