The original PlayStation can be emulated excellently on Mac OS X using the open-source emulator, PCSX-Reloaded (formerly PCSX).
The Mac OS X build is available in binary form, and mercifully it’s an app bundle too. You just double-click and go. File, load ISO, point it to a disc image, and play.
PlayStation emulation generally requires you to provide a BIOS image extracted from the console, and that’s the one thing you’ll probably have to pirate, even if you have your own physical discs. The emulator is apparently able to emulate/simulate BIOS functions, but in testing it seems like that feature is hit and miss at best. PCSXR runs best with an actual BIOS image. You have to place it in /Users/your_name/Library/Application Support/Pcsxr/Bios. Their wiki recommends SCPH7502.bin.
Also note: for what it’s worth, I had to rename my collection of disc images to .iso file extension, because PCSXR requires it.
Save states, memory card files, plugins and other supporting data get stored at /Users/your_name/Library/Application Support/Pcsxr, like a good Mac application. Maybe a little hard to find, but this is at least the standard location for application data. Not some directory that begins with a dot, in your home directory, that Finder can’t even see. And not /Library/Application Support, which is semi-hidden by Finder and access-controlled with root permissions.
You’ll want to connect a real gamepad. The PS3 controller works well, because it’s Bluetooth. Bring over a Dual Shock 3, but not one that is already turned on and paired with a PS3 in the room, because that’ll cause trouble. Turn on Bluetooth in the menu bar. The Bluetooth discovery process is janky, and you might need the mini-USB cable, but it will work, and eventually you will be able to use it 100% wirelessly. In PCSXR: open Preferences. Go to the Plugins tab. Where it says controller, select “Gamepad/Keyboard/Mouse” and click “Configure”. If the Playstation controller is connected, you should see it in the drop-down box labeled “Device”. Select it. Now in my case, none of the preset buttons were mapped to the right controller buttons, so I had to remap all of them, but it only takes a second.
Input: I expected to be able to play games originally for use with a light gun, like Point Blank, Elemental Gearbolt, Time Crisis, or PoliceNauts. They do work, but only with a controller, and not with a mouse like I hoped. Eventually, I’ll look into alternative input plugins, maybe here or here. Out of the box, it looks like PCSXR can support 2 players. There were games for PS1 that supported 4 players with the PlayStation MultiTap accessory, and there might be a plugin for this, but I haven’t searched for it.
Net play: didn’t test this yet.
Audio: there’s some skipping in the audio on my system. Increasing the cache slider for the CD reader plugin didn’t help, and there’s really nothing that looks like it would help under Audio. Turning frame skip on under graphics also didn’t help. Switching to the SDL sound driver might have helped a tiny bit, but there’s still skipping. Lammy’s audio in Um Jammer Lammy is inaudible, then it de-synchs from the gameplay and everything slows down.
Graphics: The emulated graphics enable a level of quality that an actual PlayStation could never produce. Some of the hardware limitations of the original machine meant that polygons would sometimes jiggle, and the textures would have perspective issues. It looks like PCSXR has included Mac OS X native builds of “Pete’s” OpenGL plugin, and made it the default. I’ve seen video of other graphics plugins that can be used to improve the resolution (like GDSX, although that is DirectX so would be Windows-specific), but the resolution already looks like it’s rendering at 800×600, much higher than the original console was capable of (640i at best). There’s also Pete’s “OpenGL2” plugin, which I want to look into. The image looks a little off in some way that I can’t put my finger on, like too high resolution or something. Scanlines are a nice touch but they kind of darken the image; I don’t think that’s it.