This circuit is in charge of delaying the digital signal after its conversion using a successive-approximation register. The design of the circuit is not very common, since it uses the same DAC both to generate the output audio after being delayed and for converting incoming analog signal into digital domain. Feedback and effect level are controlled by a TC9154 analog mixer chip. The DSS-1 has its operating system stored on ROM chips, so if you lose your floppy disks you can still boot the system up (unlike the E-mu Emulator, Ensoniq Mirage, and early Roland samplers which required you always have a floppy disk containing the OS). However, each time you boot up the DSS-1 you will not have any sounds available until you load a system into memory from floppy disk. This can usually take anywhere from 20 to 40 seconds, depending on the size and number of multisamples contained in that system. The floppies that the DSS-1 understands are the older DSDD (double-sided double-density) disks that were also used on the Ensoniq Mirage and on early Macintosh computers. For performance control, Korg offers up their standard 4-way joystick (same one found on DW series and Poly-800), and channel aftertouch (not polyphonic aftertouch) and velocity control. One can also assign a parameter to one of the data sliders for tweaking in realtime. It does not include portamento, an arpeggiator, or a built-in sequencer. In 2010, Tom Virostek has presented a retrofit kit for the DSS-1. This kit installs itself over the 8085 CPU board, and replaces the processor by a much more powerful and faster NEC V40 processor. This kit also extends the DRAM to 4 Msamples (against the original 256K), and allows to load the sample from a USB key. In 2012, the Dutch company KissBox introduced a VST plugin (written by B. Bouchez) designed as a librarian/editor for the DSS-1, named VSTizer DSS1. The plugin does not generate sounds by itself, it is designed to remotely control the DSS-1 over a RTP MIDI communication link. This plugin simplifies sound edition (the DSS-1 uses a single slider for the 78 parameters of a sound, combined with numerical entry via the keypad). It is also able to load and save the complete synthesizer memory over MIDI, including the samples (avoiding the use of the DSS-1 floppy disk).