High speed analog to digital converter board for an IBM PC/AT

A digitizer for converting analog signals from a video unit to digital data for analysis using a computer, wherein the digitizer comprises:

• an interface circuit coupled to the computer via interface data lines, interface address liens and interface control lines, for supplying commands from the computer to the digitizer;
• a flash analog-to-digital converter having an analog input coupled to a video output of the video unit, for digitizing analog data signals from the video unit to produce a sequence of N-bit data words at a digital output line;
• address counter means providing an address output having M bits, comprising X low order bits and (M-X) remaining bits;
• a memory comprising memory devices organized into a plurality of banks, each of said plurality of banks having address register means (M41-M42) with inputs coupled to the address output for said (M-X) remaining bits, and data register means (M54) having inputs coupled to the digital output line form the analog-to-digital converter;
• a memory decode circuit having inputs for the X low order bits form the address output, and means for decoding said low order bits to select the banks of said memory devices in turn;
• clock means coupled to the analog-to-digital converter and to the memory for supplying clock pulses at a selected frequency;
• start-up control means having a synchronizing input coupled to a synchronizing output of the video unit, means for supplying a START command from the computer via the interface circuit to set the start-up control means to a run state, means effective with the start-up circuit in the run state and responsive to a pulse at the synchronizing input for starting a digitizing sequence;
• means effective during said digitizing sequence for coupling clock pulses for the clock means to the address counter means to advance an address count on each clock pulse, so that the memory decode circuit enables the memory banks in turn to store the address in the address register means and the data word form the digital output line in the data register means, and in each of said plurality of banks the data word form the data register means is stored in the memory devices at the address from the address register means for the bank of said memory devices which is selected by said X low order bits.