Can anyone answer the question below? I have links to pictures of the question and answer. I don't understand the answer provided by the book. Why does it say in the answer, "The EPROM will assert whenever CS4 is asserted"? I thought EN had to be pulled low?
Also, in the answer, where do they get 100X XXXX from? What are those eight bits representing?
A microprocessor (μp) uses a 16-bit address bus and an 8-bit data bus. The address bus lines are labeled A15 to A0, where A15 is the most significant address bit and A0 is the least significant address bit. The microprocessor generates an active-low address strobe (AS) at the beginning of each memory access cycle to indicate that a valid address has been placed on the address bus. The AS signal is asserted for the entire memory access cycle.
In a certain application of the μp, the three most significant address bits (A15-A13) are used as inputs to a 3-of-8 decoder to generate chip-select signals (CS0 - CS7). The chip-select signals are used to enable an EPROM memory device whose address lines are tied directly to the lower 13 address lines (A12-A0) of the μp. The EPROM's output lines are enabled whenever its enable (EN) is pulled low. A figure of the microprocessor described above and the decoder truth tables are shown at the below link.
The range of addresses (expressed in hexadecimal) to which the EPROM in the figure will respond is most nearly:
A. 0000 to 1FFF
B. 4000 to 5FFF
C: 8000 to 9FFF
D: E000 to FFFF
Figure and truth table: https://ibb.co/JdRz0XX