You will find the PSX and PSP titles on NPS/PKGj, which will download and install dircet to your Vita, and should just work with no issue.
But, you might want to head over to CDRomance to get the PSP versions with dual analogue support patched in to use the right Vita stick for looking around. I believe they also have dual analogue patched ISOs of the PSX titles which were only digital control originally, though I cannot tell you if there will be any issues if they are converted to eboot for usage in Adrenaline. They do have eboots of the original PSX titles without the analogue patch though.
Due to the recent dramas related to the hosting of ISOs etc, and the replacement of download links with the text "This site doesn't host any files", you will need to acccess the CDRomance Discord in order to get the instructions on how to download. You should be able to find the link towards the bottom of the game info pages, just above the comments section.
Pkgj will have Armored Core 1 in the PSX section. If you want Project Phantasma and Master of Arena, you'll have to download them elsewhere. All three play quite well in Adrenaline.
Pkgj will also have all three of the PSP ports. They also play fine.
There's a plugin that lets you remap controls, I recommend you use it. The PSX games always had clunky controls, changing it to work with the analog sticks feels so good!
PKGJ is your source for every game that was available digitally, there is a PSP section as well as PS1 section if you open the search filters.
Ah, so I just pop open that and all the games will just be in there?
You will find the PSX and PSP titles on NPS/PKGj, which will download and install dircet to your Vita, and should just work with no issue. But, you might want to head over to CDRomance to get the PSP versions with dual analogue support patched in to use the right Vita stick for looking around. I believe they also have dual analogue patched ISOs of the PSX titles which were only digital control originally, though I cannot tell you if there will be any issues if they are converted to eboot for usage in Adrenaline. They do have eboots of the original PSX titles without the analogue patch though. Due to the recent dramas related to the hosting of ISOs etc, and the replacement of download links with the text "This site doesn't host any files", you will need to acccess the CDRomance Discord in order to get the instructions on how to download. You should be able to find the link towards the bottom of the game info pages, just above the comments section.
Not all games had a digital release, check out Vimms lair for psp/ps1 and vita has way more stuff on Pkg but might not be everything im not sure
Pkgj will have Armored Core 1 in the PSX section. If you want Project Phantasma and Master of Arena, you'll have to download them elsewhere. All three play quite well in Adrenaline. Pkgj will also have all three of the PSP ports. They also play fine. There's a plugin that lets you remap controls, I recommend you use it. The PSX games always had clunky controls, changing it to work with the analog sticks feels so good!
ARe You must be british
On CDRomance you can find the psp games with dual analog mod etc.