Z84C90_12 Datasheet, PDF (29/56 Pages) Zilog, Inc. – KIO Serial/Parallel Counter/Timer

Z84C90 KIO Serial/Parallel Counter/Timer
Product Specification
22
D7 D6 D5 D4 D3 D2 D1 D0
V0
V1*
V2*
V3*
V4
Interrupt vector
V5
V6
V7
Note: *Variable if Status Affects Vector is also programmed.
Figure 21. SIO Read Register 2 (Channel B only)
Write Registers. SIO Channel B contains eight write registers while Channel A contains
only seven that are programmed to configure the operating modes and characteristics of
each channel. With the exception of WR0, programming the write registers is a two-step
operation. The first operation is a pointer written to WR0 that points to the selected regis-
ter. The second operation is the actual control word data that is written into the register to
configure the SIO channel. See Figures 22 through 29 to examine the details of these write
registers.
PS011804-0612
Register Programming