Configuration circuitry comprising: a decoding circuit configured to receive a base configuration data set (343, 540) defining a base circuit design for a configurable integrated circuit and a compressed first configuration data difference set (350, 510), wherein the compressed first configuration data difference set (350, 510) includes compressed data differences between the base configuration data set (343, 540) and a first configuration data set (340, 550) defining a first circuit design for the configurable integrated circuit and preserving portions of the base configuration data set (343, 540), and wherein the decoding circuit comprises: a first circuit configured to receive the compressed first configuration data difference set (350, 510) and to decompress the compressed first configuration data difference set (350, 510) to create a decompressed first configuration data difference set; and a second circuit configured to receive the base configuration data set (343, 540) and the decompressed first configuration data difference set from the first circuit, and configured to perform a bit-wise exclusive OR or exclusive NOR operation between the base configuration data set (343, 540) and the decompressed first configuration data difference set to restore the first configuration data set (340, 550). a decoding circuit configured to receive a base configuration data set (343, 540) defining a base circuit design for a configurable integrated circuit and a compressed first configuration data difference set (350, 510), wherein the compressed first configuration data difference set (350, 510) includes compressed data differences between the base configuration data set (343, 540) and a first configuration data set (340, 550) defining a first circuit design for the configurable integrated circuit and preserving portions of the base configuration data set (343, 540), and wherein the decoding circuit comprises: a first circuit configured to receive the compressed first configuration data difference set (350, 510) and to decompress the compressed first configuration data difference set (350, 510) to create a decompressed first configuration data difference set; and a second circuit configured to receive the base configuration data set (343, 540) and the decompressed first configuration data difference set from the first circuit, and configured to perform a bit-wise exclusive OR or exclusive NOR operation between the base configuration data set (343, 540) and the decompressed first configuration data difference set to restore the first configuration data set (340, 550). a first circuit configured to receive the compressed first configuration data difference set (350, 510) and to decompress the compressed first configuration data difference set (350, 510) to create a decompressed first configuration data difference set; and a second circuit configured to receive the base configuration data set (343, 540) and the decompressed first configuration data difference set from the first circuit, and configured to perform a bit-wise exclusive OR or exclusive NOR operation between the base configuration data set (343, 540) and the decompressed first configuration data difference set to restore the first configuration data set (340, 550).