Serial data is entered in a frame of 256 bits, clocked by RTS. SOP1 provides frame synchronisation. Serial data is stored in the Output List within the pRAM-256 and may be 'connected' to any pRAM input by the use of the connection pointer table.
Serial data is continuously read at a maximum rate of 6000 frames per second (training disabled) or a rate of 4000 frames per second (training enabled).
Where binary data is available in parallel form, an external parallel to serial conversion is required. This can be achieved through the use of a shift register as shown above. The SOP1 strobe can be used to transfer data from the parallel port to the shift register.
Such data may be input using the serial ports as above, but conversion of the data into spike trains must be performed using external hardware.
Alternatively, the real-valued data may be stored, one value per pRAM, in the pRAMs' weight memory. The pRAMs used in this way are non-learning and are only used to generate spike trains for the input layer of the neural network.
In order to write to the SRAM weight memory, the pRAM-256 is halted. When HALT_ACK is asserted at the end of the pass, the pRAM-256 address and data buses and /WE are tri-stated so that the SRAM can be written to by an external controller.