function plot_sp( num_std, DRAWALL )

if (~exist('num_std'))
    num_std = 5;
end

if (~exist('DRAWALL'))
    DRAWALL = 0;
end

load( sprintf( 'sp%d_data_ext', num_std ) );

fig = 565;
figure( fig+1 ); clf;

if ( DRAWALL )
    starting_channel = 1;
    figure( fig ); clf;
else
    starting_channel = 25;
end

for channel = starting_channel:64
    z = z_data(:,channel);
    sp = sp_data{channel};
    
        if ( channel < 25 )
            subplot(3,8,channel);
        else
            figure( fig+1 );
            subplot(5,8,channel-24);
        end

        plot( sp_t, z ); hold on;
        plot( [sp_t(1) sp_t(end)], [threshold(channel) threshold(channel)], 'g' );
        plot( [sp_t(1) sp_t(end)], [-threshold(channel) -threshold(channel)], 'g' );
        plot( sp, zeros(length(sp),1), 'rx' );
        axis tight;
        AX = axis;
        tx = text( 0.6*AX(1)+0.4*AX(2), 0.95*AX(3)+0.05*AX(4), ...
           sprintf( 'Ch %d', channel ) );
        set( tx, 'fontsize', 10, 'fontweight', 'bold' );
        
        drawnow;
end