My first PDA, Casio Pocket Viewer PV 100 had 2 MB of flash ram when I bought it in 2000. In the last millenium, I would say. It is heartening to see that atleast now the mass market PDA manufacturers have started using flash memories for PDA RAMs. Another thing I miss from my PV is that it used 2 normal AAA batteries. I replaced it once in six months without any loss of data.
Today, I am using Motorola A760, my fifth PDA (II – Palm IIIc, III – Audiovox Maestro, IV – Sharp Zaurus SL 5500) and I recharge my batteries every night.