The t5135 has these IDE Flash chips installed in them:

t5135 Flash IDE Chip - Copyright 2007

t5135 Flash IDE Chip 2 - Copyright 2007

These are called “44-pin IDE Flash Modules”, and can range from approximately $10 to several hundred dollars. I’m somewhat disappointed with the speed capabilities I’ve been reading about. I was hoping they would be much faster, though if I understand correctly, they can reach up to 66 MB/s in UDMA mode 4.