Timex FDD 3
There are two versions of the disk system created by Timex Portugal, the FDD and the FDD-3000. Both require a machine specific interface. These were sold for the TS2068, TC2068 and TC2048 machines but third parties have subsequently supplied interfaces which work with the 128K ZX Spectrum (these are also required for the TC2128 and TC2144).
Both systems have their own Z80 CPU but while the FDD only has 16K of RAM, the FDD 3000 has 64K and can be used as a CP/M terminal. The FDD consists of three separate boxes while the FDD-3000 integrates a PSU and two 3" drives. It is possible, although tricky, to upgrade an FDD to an FDD-3000. Both systems can use 3.5" and 5.25" drives in place of (or in addition to) the 3" drives.
The interface uses a logic circuit to page in the 4KB FDD ROM whenever there is a call to 0x0000 or 0x0008 and page it out again whenever there is a call to 0x0604. When it is needed the FDD ROM is paged in at 0x0000 and 0x1000 and the area 0x2000-0x3fff holds eight copies of 1K of RAM or four copies of 2K of RAM. The disk drive is controlled by port 0xef.