Differential PCM coding of video signals with tabulated memories

DPCM coders and decoders can be built using tabulated memories and-in the simplest case-external registers. Such system, its variants, reduced prediction accuracy and possible other uses of tabulated memories are discussed. Available or already announced ROMs are suitable for building the codecs. With 5-bit DPCM, a coder needs a mask ROM, 64 k*16, and a decoder needs a 8 k*8 PROM with external registers. Arrangements of tabulated memories in four versions of coders are shown in their relation to the TV picture.