What is your projected use case for this laptop?
edit- sorry wrong manual link, one moment (maybe)
This should be correct:
C655-S5132 - read user manual online or download in PDF format. Pages in total: 4.
manualsbrain.com
DDR2 up to 4GB it says there. I cannot find a specific on the speed, would take some digging into the CPU/chipset spec perhaps.
IMO the best thing you could do with this is retire it and not spend any money on it. Even something really light like Lubuntu or other light OS is going to put that Celeron to task. I doubt this will do more than read text, almost certain it will not be capable of video playback online, such at YT.
As you may already be aware Toshibas laptop line was discontinued, acquired by Sharp in 2019 and basically doesn't exist as the same company anymore.