a memory;

a device controller that receives commands from a host over a serial bus and controls access to the memory for the host;

wherein the device controller generates an activity signal when the memory is being accessed;

a pattern-decoding generator that receives the activity signal from the device controller, the pattern-decoding generator generating a sequence of data signals on a plurality of data lines, the sequence being activated in response to the activity signal; and

a display having a plurality of light-emitting diodes (LED's) that are driven by the plurality of data lines from the pattern-decoding generator to produce a visually changing sequence of illuminated LED's;

wherein the visually changing sequence of illuminated LED's comprises at least four visually different states,

whereby the visually changing sequence on the display is generated when the memory is being accessed.