{"id":215308,"date":"2025-05-16T17:42:57","date_gmt":"2025-05-16T17:42:57","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=215308"},"modified":"2025-05-16T17:42:59","modified_gmt":"2025-05-16T17:42:59","slug":"using-64-x-8-rom-chips-with-an-enable-input-construct-a-512-x-8-rom-with-eight-chips-and-a-decoder-2","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/16\/using-64-x-8-rom-chips-with-an-enable-input-construct-a-512-x-8-rom-with-eight-chips-and-a-decoder-2\/","title":{"rendered":"Using 64 \u00d7 8 ROM chips with an enable input, construct a 512 \u00d7 8 ROM with eight chips and a decoder."},"content":{"rendered":"\n<p>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<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-0-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p>To construct a <strong>512 \u00d7 8 ROM<\/strong> using <strong>64 \u00d7 8 ROM<\/strong> chips with <strong>eight chips<\/strong> and a <strong>decoder<\/strong>, we need to arrange the chips and decoder correctly.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">\u2705 <strong>Correct Answer:<\/strong><\/h3>\n\n\n\n<p>Use <strong>8 of the 64 \u00d7 8 ROM chips<\/strong> and connect their <strong>enable inputs<\/strong> to the <strong>outputs of a 3-to-8 decoder<\/strong>. Feed the <strong>3 most significant address lines<\/strong> (A6, A5, A4) into the <strong>decoder<\/strong>, and feed the <strong>remaining 6 address lines<\/strong> (A3 to A0 and A2 to A0, depending on naming) into <strong>each ROM chip<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">\ud83e\udde0 <strong>Detailed Explanation (300+ words):<\/strong><\/h3>\n\n\n\n<p>A <strong>64 \u00d7 8 ROM<\/strong> means it has <strong>64 memory locations<\/strong> (or addresses), each holding <strong>8 bits<\/strong> of data. To access 64 locations, you need <strong>6 address lines<\/strong>, because 26=642^6 = 64.<\/p>\n\n\n\n<p>You want to build a <strong>512 \u00d7 8 ROM<\/strong>, which means:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>512 memory locations<\/strong><\/li>\n\n\n\n<li><strong>Each location stores 8 bits<\/strong><\/li>\n\n\n\n<li>To address 512 locations, you need <strong>9 address lines<\/strong> because 29=5122^9 = 512<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">\ud83d\udca1 Step-by-Step Construction:<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Number of Chips Needed:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Each chip can store 64 bytes.<\/li>\n\n\n\n<li>51264=8\\frac{512}{64} = 8, so you need <strong>8 ROM chips<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Decoder Requirement:<\/strong>\n<ul class=\"wp-block-list\">\n<li>You need to select <strong>one ROM chip at a time<\/strong>, based on the <strong>upper address bits<\/strong>.<\/li>\n\n\n\n<li>A <strong>3-to-8 decoder<\/strong> (like 74LS138) takes <strong>3 input lines<\/strong> and activates one of <strong>8 outputs<\/strong>.<\/li>\n\n\n\n<li>Connect the <strong>3 most significant bits<\/strong> of the address lines (A8, A7, A6) to the inputs of the <strong>decoder<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>ROM Enable Connections:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Connect each of the <strong>8 decoder outputs<\/strong> to the <strong>enable (chip select)<\/strong> input of each ROM chip.<\/li>\n\n\n\n<li>This ensures <strong>only one chip is active<\/strong> at a time.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Address Lines to Chips:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Each chip still needs to know which of its 64 locations to access.<\/li>\n\n\n\n<li>Connect the <strong>lower 6 address lines<\/strong> (A5 to A0) to the <strong>address inputs<\/strong> of <em>all<\/em> the ROM chips in parallel.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Data Lines:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Connect the <strong>8 data output lines<\/strong> from each chip to a <strong>common 8-bit data bus<\/strong>.<\/li>\n\n\n\n<li>Only the <strong>enabled chip<\/strong> will drive the data bus (since only one chip is active).<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">\u2705 Summary:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use <strong>a 3-to-8 decoder<\/strong> for selecting among <strong>8 ROM chips<\/strong><\/li>\n\n\n\n<li>Use <strong>upper 3 address lines<\/strong> to drive the decoder<\/li>\n\n\n\n<li>Use <strong>lower 6 address lines<\/strong> for ROM address inputs<\/li>\n\n\n\n<li>Connect <strong>data outputs<\/strong> to a common bus<\/li>\n\n\n\n<li>Result: A working <strong>512 \u00d7 8 ROM<\/strong> system using <strong>eight 64 \u00d7 8 ROM chips<\/strong><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>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: To construct a 512 \u00d7 8 ROM using 64 \u00d7 8 ROM chips with eight chips and a decoder, we need to arrange the chips and decoder [&hellip;]<\/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-215308","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/215308","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=215308"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/215308\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=215308"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=215308"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=215308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}