It is required to connect memory to a digital system such th

It is required to connect memory to a digital system such that the initial 16 KB memory is used as ROM and the next 64 KB as RAM. (a) Show the address map if we have RAM chips of size 32K times 4 only and ROM chips of size 8K times 8 only as shown below: (Name the chips as R MO, RAMI etc. while showing multiple chips in the address map). (b) Show the interconnections of the memory chips using decoders of appropriate sizes.

Solution

Solution:

The address map of ram and Rom chips involves two steps.

step1:

Firstly combine 2K x 8ROM into 2k X 32 ROM . It as to be connected in parallel and the input address are common. . The data outputs are kept separate to for the 32 lines required. The chips are enable and a read line are active low.
step2:

In this step it involves combining four \"2k x 32 bit\" ROM units. The input ADDRESS LINES (A0 - A10) and output address are also connected together in parallel. This just leaves the problem of the CONTROL LINES. The read line is commoned to ROM to output the data with a single \'read\' signal. The chip is enabled are used as an extra address signal to ensure that only ONE 2k x 32 bit block is addressed at any given time. The input addresses A11 and A12 to give the full 8K address for the ROM and add a 2 to 4 line decoder to convert these address lines to CHIP ENABLE selections.