Intel Microcontroller, 80C196NU manual System BUS AC Timing Specifications, Rd# Wrh# Wrl#, We# Oe#

Models: Microcontroller 80C196NU 8XC196NP

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8XC196NP, 80C196NU USER’S MANUAL

Figure 13-19 illustrates the use of the write strobe mode in a mixed 8-bit and 16-bit system with two flash memories and one SRAM. The WRL# signal, which is generated for all 8-bit writes (Table 13-14), is used to write bytes to the SRAM. Note that the RD# signal is sufficient for sin- gle-byte reads on a 16-bit bus. Both bytes are put onto the data bus and the memory controller discards the unwanted byte.

CS1#

CS0#

A19:0

AD15:8

8XC196

AD7:0

RD#

WRH#

WRL#

A18:1

AD15:8

CE#

A17:0

D7:0

Flash

256K×￿8

High

WE# OE#

A18:1

AD7:0

CE#

A17:0

Flash

256K×￿8

Low

D7:0

WE# OE#

A12:0

AD7:0

CE#

A12:0

SRAM

8K×￿8

D7:0

WE# OE#

A2439-03

Figure 13-19. A System with 8-bit and 16-bit Buses

13.9 SYSTEM BUS AC TIMING SPECIFICATIONS

Refer to the latest datasheet for the AC timings to make sure your system meets specifications. The major external bus timing specifications are shown in Figure 13-20 through 13-23.

13-36

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Intel Microcontroller, 80C196NU, 8XC196NP manual System BUS AC Timing Specifications, Rd# Wrh# Wrl#, We# Oe#