{"id":196786,"date":"2025-03-05T20:38:14","date_gmt":"2025-03-05T20:38:14","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=196786"},"modified":"2025-03-05T20:38:25","modified_gmt":"2025-03-05T20:38:25","slug":"using-64-x-8-rom-chips-with-an-enable-input","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/03\/05\/using-64-x-8-rom-chips-with-an-enable-input\/","title":{"rendered":"Using 64 \u00d7 8 ROM chips with an enable input"},"content":{"rendered":"\n

Using 64 \u00d7 8 ROM chips with an enable input, construct a 512 \u00d7 8 ROM with eight chips and a decoder.<\/p>\n\n\n\n

The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n

Constructing a 512 \u00d7 8 ROM Using 64 \u00d7 8 ROM Chips and a Decoder<\/strong><\/h3>\n\n\n\n

Solution<\/strong><\/h4>\n\n\n\n

To construct a 512 \u00d7 8 ROM<\/strong> using 64 \u00d7 8 ROM<\/strong> chips, we need to meet the requirement of storing 512 words<\/strong> of 8-bit<\/strong> data.<\/p>\n\n\n\n

Each 64 \u00d7 8 ROM<\/strong> chip can store 64 words<\/strong> (or addresses), each being 8 bits wide<\/strong>. To reach 512 words<\/strong>, we divide:<\/p>\n\n\n\n

[
512 \\div 64 = 8
]<\/p>\n\n\n\n

Thus, eight (8) ROM chips<\/strong> are required.<\/p>\n\n\n\n

To select one of the eight chips at a time, we need a 3-to-8 decoder<\/strong> since:<\/p>\n\n\n\n

[
2^3 = 8
]<\/p>\n\n\n\n

The three most significant address lines (A6, A7, A8)<\/strong> from the 9-bit address bus (since ( 2^9 = 512 )) are used as inputs to this 3-to-8 decoder<\/strong>. The decoder activates exactly one of the eight ROM chips<\/strong> at a time through its chip enable (CE) input<\/strong>.<\/p>\n\n\n\n

Each ROM chip receives the lower six address lines (A0 – A5)<\/strong> as input to access one of its 64 memory locations<\/strong>. The output data buses of all ROM chips<\/strong> are connected together<\/strong> in a shared tri-state<\/strong> configuration, meaning only the selected ROM will place data on the bus.<\/p>\n\n\n\n

\n\n\n\n

Connections:<\/strong><\/h3>\n\n\n\n
    \n
  1. Address Bus (9-bit)<\/strong><\/li>\n<\/ol>\n\n\n\n
      \n
    • A0 – A5<\/strong> go to all ROM chips.<\/li>\n\n\n\n
    • A6 – A8<\/strong> go to the 3-to-8 decoder.<\/li>\n<\/ul>\n\n\n\n
        \n
      1. Decoder<\/strong><\/li>\n<\/ol>\n\n\n\n
          \n
        • Takes A6, A7, A8 as inputs.<\/li>\n\n\n\n
        • Outputs are connected to the chip enable (CE)<\/strong> of each ROM chip.<\/li>\n<\/ul>\n\n\n\n
            \n
          1. Data Bus (8-bit)<\/strong><\/li>\n<\/ol>\n\n\n\n
              \n
            • Outputs of all ROM chips are tied together in tri-state mode.<\/li>\n<\/ul>\n\n\n\n
                \n
              1. Control Lines<\/strong><\/li>\n<\/ol>\n\n\n\n
                  \n
                • Common read and write control lines.<\/li>\n<\/ul>\n\n\n\n

                  This setup ensures that at any moment, only one ROM chip is active<\/strong>, enabling access to the full 512 \u00d7 8 memory<\/strong>.<\/p>\n\n\n\n

                  Now, I will generate an image illustrating this configuration.<\/p>\n\n\n\n

                  \"\"<\/figure>\n\n\n\n

                  Here is the digital circuit diagram illustrating the construction of a 512 \u00d7 8 ROM using eight 64 \u00d7 8 ROM chips and a 3-to-8 decoder.<\/p>\n","protected":false},"excerpt":{"rendered":"

                  Using 64 \u00d7 8 ROM chips with an enable input, construct a 512 \u00d7 8 ROM with eight chips and a decoder. The correct answer and explanation is : Constructing a 512 \u00d7 8 ROM Using 64 \u00d7 8 ROM Chips and a Decoder Solution To construct a 512 \u00d7 8 ROM using 64 \u00d7 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-196786","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/196786","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=196786"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/196786\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=196786"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=196786"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=196786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}