6 Serial Controller: Zilog ESCC
The Sealevel card uses a UART from Zilog. UART stands for
Universal Asynchronous Receiver/Transmitter. Its purpose is to convert
data to and from a serial interface. Download the User Manual from the Zilog website if you have not already done this. In the User Manual, hardware related. You should skim over these chapters. The
most important chapter related to this tutorial is Chapter 5, Register
Descriptions . The User Manual describes the Zilog SCC/ESCC
family: SCC, NMOS, CMOS, ESCC, EMSCC, Z80X30 and Z85X3X.
We are interested only on the ESCC since it's used on the Sealevel serial
card. The Zilog ESCC has read and write registers. Registers
are internal locations for data storage. The ESCC has 15 write registers
(WRs) and 15 read registers(RRs) and a FIFO buffer 8 bytes deep.
Typically, we are going to use these registers:
Each register is at a different address relative to the base address.
For example, Let's say that the base address is at 0x300 and the register RR1 is 1 byte from the base address. To access to RR1 to read, we
use inb(0x301).