I picked up a Radio Shack Pocket Repeat (62-2482) which is a newer version than the 2 on Handheld Museum. The chip is an 18-pin DIP, the Zilog Z8 Z86C04, dated 9520. This version has 1K mask ROM. I'm not sure if it can be electronically dumped; the Z8 supports external program memory, but this package doesn't have 13 of the pins used for that. There is also a ROM protect bit that might have been set.