An inexpensive RS-232 based controller for Sony Control-L protocol. One D-box can control 2 or 4 VCRs simultaneously.
Device built by Dave Dunfield. Software is C. But, stored in an EEPROM, so end users do not see any software, just a device.
Much cheaper per controlled VCR than the Sony V-Box.
Only supports control-L, but with the development kit, could be extended to other protocols. Not a mass produced product at this time.