What are the ranges of addresses for the partial-address decoders of Example 9.7?

A 32KB EPROM needs a starting address of 30000, and a 32KB RAM needs a starting address of 20000. The circuitry in Figure 9.17 shows how these addresses are partially decoded. In this example, three-input NAND gates are used to do the decoding. All three inputs must be high for the output to go low (and enable the memories). IO/M- is inverted, so that it presents a 1 when low. A_17 is connected directly, because it is high in both the RAM and EPROM address ranges. Only A_16 changes. It is low for the RAM range and high for the EPROM range. Address lines A_0 through A_14 are used by the memories themselves. FIGURE 9.17 Partial-address decoder for 32KB EPROM at 30000, and 32KB RAM at 20000 Can you determine the range of addresses for each memory? A 32KB EPROM needs a starting address of 30000, and a 32KB RAM needs a starting address of 20000. The circuitry in Figure 9.17 shows how these addresses are partially decoded. In this example, three-input NAND gates are used to do the decoding. All three inputs must be high for the output to go low (and enable the memories). IO/M- is inverted, so that it presents a 1 when low. A_17 is connected directly, because it is high in both the RAM and EPROM address ranges. Only A_16 changes. It is low for the RAM range and high for the EPROM range. Address lines A_0 through A_14 are used by the memories themselves. FIGURE 9.17 Partial-address decoder for 32KB EPROM at 30000, and 32KB RAM at 20000 Can you determine the range of addresses for each memory