Attaching Multiple Devices On The Rom Interface - Intel 21555 User Manual

Parallel ROM Interface
.
Figure 18. Attaching Multiple Devices on the ROM Interface
21555
90
sr_cs
pr_ad[7:0]
pr_wr_l
pr_rd_l
pr_ale_l
pr_clk
pr_cs_l(pr_rdy)
21555 Non-Transparent PCI-to-PCI Bridge User Manual
pr_ad[0]
pr_ad[1]
pr_ad[2]
en
8-bit register
en
8-bit register
en
8-bit register
a21
a22
a23
en
decoder
Other Device Read Strobe
Other Device Write Strobe
Other Device Data
Other Device Ready Line
Serial
sr_cs
ROM
sr_ck
sr_di
sr_do
Parallel
d[7:0]
ROM
W E #
O E #
a[7:0]
a[15.8]
a[20:16]
C E#
Other
Device
Selects
A7473-01