Interesting. I've asked that because the gp2x also had a second core for video purpose, with very little cache. it could access 32MB of memory but with the same bus than the main core, so it was not optimal. Even with those limitation, it give a nice boost to some project (picodrive emulated some stuff on it IIRC, gngeo all the sound emulation core: z80+ym2610)
Even if there is not much ram (I've read 48kbit too I think), I guess there is some mechanism to transfer data from the main memory to the scratch pad, maybe a DMA? if it's fast enough it could be useful.