implementations of the Z8030 and Z8530. Plug compatible with the early versions, adding the 2x speed when used with the external clock, and a number of bug fixes and improvements in the link layer protocols. Z80230 and Z85230 Updated CMOS implementations of the Z80C30 and Z85C30, also known as the ESCC Z85233 Updated version of the Z85230 (only), also known as the EMSCC References External links Z80C30 product brief Z85C30 product brief Z80C30/Z85C30 Serial Communications Controllers Product Specification Z80C30/Z85C30/Z80230/Z85230/Z85233 SCC/ESCC User Manual FreeBSD scc(4) driver Input/output integrated circuits