{"id":214334,"date":"2025-05-14T06:16:25","date_gmt":"2025-05-14T06:16:25","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=214334"},"modified":"2025-05-14T06:16:27","modified_gmt":"2025-05-14T06:16:27","slug":"using-64-x-8-rom-chips-with-an-enable-input-construct-a-512-x-8-rom-with-eight-chips-and-a-decoder","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/14\/using-64-x-8-rom-chips-with-an-enable-input-construct-a-512-x-8-rom-with-eight-chips-and-a-decoder\/","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 class=\"wp-block-paragraph\"> <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">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 class=\"wp-block-paragraph\"><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 class=\"wp-block-paragraph\">To construct a <strong>512 \u00d7 8 ROM<\/strong> using <strong>64 \u00d7 8 ROM chips<\/strong> (with an enable input), you will need:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Eight 64 \u00d7 8 ROM chips<\/strong><\/li>\n\n\n\n<li><strong>A 3-to-8 line decoder<\/strong><\/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\"><strong>Correct Answer:<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Use the <strong>3 most significant address bits (A6, A5, A4)<\/strong> to drive a <strong>3-to-8 decoder<\/strong>, which enables <strong>one of the eight ROM chips<\/strong>. Each ROM chip handles <strong>64 addresses (2\u2076)<\/strong>, using the <strong>6 least significant address bits (A3 to A0)<\/strong> as input. Connect the outputs of all ROM chips together in a <strong>wired-OR or tri-state configuration<\/strong>, depending on the chip type.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Detailed Explanation (300+ words):<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A <strong>64 \u00d7 8 ROM chip<\/strong> means it can store 64 words, each 8 bits wide. Since $64 = 2^6$, the ROM requires <strong>6 address lines (A0 to A5)<\/strong>. To build a <strong>512 \u00d7 8 ROM<\/strong>, we need a total of 512 memory locations (i.e., $512 = 2^9$), each also 8 bits wide.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Thus, our goal is to create a ROM with:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>9 address lines (A0 to A8)<\/strong><\/li>\n\n\n\n<li><strong>512 memory locations<\/strong><\/li>\n\n\n\n<li><strong>8 data bits per location<\/strong><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Since each chip stores 64 locations, and we need 512, we divide:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">$$<br>\\frac{512}{64} = 8 \\text{ chips needed}<br>$$<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">To manage these 8 chips, we must <strong>select one chip at a time<\/strong> based on the address being accessed. This is where the <strong>decoder<\/strong> comes in.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Decoder Integration<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">We use the <strong>3 most significant bits (A8, A7, A6)<\/strong> of the 9-bit address to drive a <strong>3-to-8 decoder<\/strong>. Each output line of the decoder connects to the <strong>Enable (EN)<\/strong> input of a single ROM chip. The decoder activates only one output line at a time, based on the 3-bit input, enabling the corresponding ROM chip.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Address Lines to ROM Chips<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>A5 to A0<\/strong> go to the address inputs of <strong>all eight ROM chips<\/strong> (since they all share these lines).<\/li>\n\n\n\n<li>Only the ROM chip selected by the decoder (via its enable input) will be active and place data on the data bus.<\/li>\n\n\n\n<li>Outputs from all chips are connected in parallel, with only the selected chip allowed to drive the data bus (via tri-state outputs or output enable logic).<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This method ensures the ROM behaves as a <strong>single 512 \u00d7 8 memory<\/strong>.<\/p>\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 an enable input), you will need: Correct Answer: Use the 3 most significant [&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-214334","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/214334","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=214334"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/214334\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=214334"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=214334"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=214334"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}