Designed for older systems or 32-bit Windows. It uses DLPORTIO for parallel port (LPT) keying, which is not compatible with 64-bit Windows.
For amateur radio operators, is an essential plugin for MMTTY that enables Frequency Shift Keying (FSK) transmission through USB-to-serial adapters and parallel ports. Without it, many modern computers struggle to generate the precise timing required for RTTY (Radioteletype) due to the limitations of standard USB UARTs. Understanding EXTFSK vs. EXTFSK64 mmtty extfsk download
Before downloading, determine which version fits your operating system: Designed for older systems or 32-bit Windows
The primary host for ExtFSK106.zip, which contains the original DLL and source code. mmtty extfsk download