PC87200VUL160A NSC [National Semiconductor], PC87200VUL160A Datasheet - Page 5

• Manufacturer Part Number: PC87200VUL160A
• Description: PC87200 PCI to ISA Bridge
• Manufacturer: NSC [National Semiconductor]

3.0 Device Overview
PCICLK
PCPCIREQ
PCPCIGNT#
SERIRQ
Period
21:18
Table 1. SERIRQ Slave Generation Periods
10
11
12
13
14
15
16
17
1
2
3
4
5
6
7
8
9
#
start
Signal Generated
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
IOCHK#
CH0
IRQ10
IRQ11
IRQ12
IRQ14
IRQ15
IRQ3
IRQ4
IRQ5
IRQ6
IRQ7
IRQ9
(Continued)
CH1
CH2
Figure 1. PC87200 PC/PCI DMA Topology
# of clocks past
Figure 2. Channel Passing Protocol
62,59,56, 53
CH3
Start
PCPCIGNT#
11
14
17
20
23
26
29
32
35
38
41
44
47
50
2
5
8
CH4
PC/PCI DMA
Primary Bus
Arbiter
PC/PCI DMA Interface Support
CH5
5
3.4 PROHIBIT signal support
The chipset will use this signal to claim the BIOS first and
then deassert the "PROHIBIT" signal to configure the PCI
to ISA bridge to continue the boot sequence.
Special test mode support is provided by means of the
BPD# pin. When this test mode is active, the PC87200 will
enable positive memory decode during boot up to enable
the host to look for boot ROM on ISA card.
PROHIBIT will be a don’t care in this test mode at boot up
for the ROM BIOS range, but should function normally after
booting
3.5 PC/PCI DMA Interface Support
The PC87200 operates as a PC/PCI DMA Secondary Arbi-
tration Bridge. The PC87200 can pass all seven legacy ISA
bus DMA channel requests to the PC/PCI DMA Primary
Bus Arbiter using the channel passing protocol defined in
the Moble PC/PCI DMA Arbitration and Protocol Specifica-
tion (Revision 2.2). Figure 1 shows the topology of the
PC87200 PC/PCI DMA requests and grants:
The PC87200 converts the seven legacy ISA bus DMA
requests (DREQ0, 1, 2, 3, 5, 6 and 7) into a serial PC/PCI
DMA compliant REQ# sequence and converts the corre-
sponding PC/PCI DMA GNT# sequence into the appropri-
ate DMA acknowledge (DACK0-3, 5-7#). This PC/PCI DMA
expansion
Figure 2.
PCPCIREQ#
CH6
CH7
Channel
PC87200
Passing
start
bit 0
Protocol
ISA Bus
PCI Bus
bit 1
www.national.com
bit 2
is
illustrated