according to other post i have read here :
“Yes, it will work. Apple has stuck with Toshiba 1.8” 4200rpm ata-5 (now 6) hard drives since the inception of its hard drive based ipods, so any of these hdds should be compatible with the tr.” from Medstu
[quote author=“mbautad”]Is it possible to install a hard disk of 2.5” to him?
Yes if you dont put the case & keyboard back
seriously there is not enough space, just compare a 2.5 and 1.8 and you ll understand by yourself. Plus the connectors a different.