The TPDD is listed as Available 10/30/85 in the Radio Shack 1986 catalog. The TPDD2 - First shows up in the Radio Shack 1988 catalog, however it also shows up in the Portable 100 magazine in the September 1987 issue.
The TRS-80 Microcomputer News was good about availability dates for new products, but unfortunately it was discontinued in June 1984, before either of these products were announced. Regards, Peter
