Z8018010VSG Datasheet, PDF (80/85 Pages) Zilog, Inc. – Microprocessor Unit

Z80180
Microprocessor Unit
74
I/O Control Register (ICR)
ICR allows relocating of the internal I/O addresses. ICR also controls enabling/disabling of
the IOSTOP mode (Figure 78).
I/O Control Register (ICR: I/O Address = 3Fh)
Bit 7
6
5
4
3
2
1
0
IOA7 IOA6 IOSTP
—
—
—
—
—
R/W R/W R/W
Figure 78. I/O Control Register (ICR: I/O Address = 3Fh)
IOA7, 6: I/O Address Relocation (bits 7,6)
IOA7 and IOA6 relocate internal I/O as illustrated in Figure 79.
Note: ^{The high-order 8 bits of 16-bit internal I/O address are always 0. IOA7 and IOA6 are}
cleared to 0 during RESET.
IOA7–IOA6 = 1 1
IOA7–IOA6 = 1 0
IOA7– IOA6 = 0 1
IOA7–IOA6 = 0 0
00FFh
00C0h
00BFh
0080h
0070h
0040h
003Fh
0000h
Figure 79. I/O Address Relocation
IOSTP: IOSTOP Mode (bit 5)—IOSTOP mode is enabled when IOSTP is set to 1. Normal
I/O operation resumes when IOSTOP is reprogrammed or RESET to 0.
PS014004-1106
Architecture