{"id":4365,"date":"2021-01-25T17:06:00","date_gmt":"2021-01-25T20:06:00","guid":{"rendered":"http:\/\/augustobaffa.pro.br\/site\/?p=4365"},"modified":"2021-03-18T17:11:12","modified_gmt":"2021-03-18T20:11:12","slug":"building-a-zx80-zx81","status":"publish","type":"post","link":"https:\/\/augustobaffa.pro.br\/site\/en\/2021\/01\/building-a-zx80-zx81\/","title":{"rendered":"Building a ZX80 \/ ZX81"},"content":{"rendered":"

Probably the youngest don’t now this, but in the early 1980s, there were some personal computer initiatives like Apple II (Apple Computers, 1977), PET (Commodore International, 1977), TRS-80 (Tandy Corporation \/ Radio Shack, 1977) that already dominated the international market.<\/p>\n

\"Apple

Apple ][<\/p><\/div>\n

\"PET\"

PET<\/p><\/div>\n

\"TRS-80\"

TRS-80<\/p><\/div>\n

This was made possible by the very first Altair 8800 (Micro Instrumentation Telemetry Systems, 1975) and its clone IMSAI 8080 (IMS Associates Inc, 1975). The current standard computer is a direct descendant of the IBM PC 5150 which would only be released in 1981.<\/p>\n

\"Altair

Altair 8800<\/p><\/div>\n

\"IMSAI

IMSAI 8800<\/p><\/div>\n

Until that moment, most hobbyists and enthusiasts had only seen a computer in magazines or inside universities and companies – and we are talking about other countries! In Brazil, a market reserve was created during the military government period, which encouraged the strategic market for national computers.<\/p>\n

It was in this scenario that in 1980 in England, Sinclair Radionics – a company that created innovative yet inexpensive devices, creator of the first pocket TV and pocket calculator in the western market – became Sinclair Computers. His objective was exactly the same: to embark on the innovative technology of the moment, but at a low and affordable price. This not only allowed the access of a large part of the population to the world of information technology, but also allowed to produce a cheaper computer even here in Brazil.<\/p>\n

\"ZX80\"

ZX80<\/p><\/div>\n

\"ZX81\"

ZX81<\/p><\/div>\n

In the brazilian market reserve, many companies cloned computers and sold what was possible: We had clones of Apple (CCE, Unitron, Miamar, Microdigital), Sinclair (Microdigital) and MSX licenses (here for sharp and gradient).<\/p>\n

I learned to program on a Tk82c (brazilian ZX81 clone). It was my first computer (and first in my home). So, I decided to try to reassemble this computer from scratch – the whole project. The ZX80 came with the design scheme in the manual but the ZX81 implemented a good part on a single chip (rare today – it is no longer manufactured) in order to make the project cheaper. On this website ( http:\/\/searle.x10host.com\/zx80\/zx80.html ), Grant Searle (an English electronics enthusiast) describes the original project and the expansion for the ZX81 – the same expansion that was used by microdigital in the initial clones.<\/p>\n

My goal is to study the basic electronics of computers and reproduce it. I chose the ZX80 for its affective value but also because it is very simple to understand and reproduce. The objectives of the project are:<\/p>\n

    \n
  • document the process in a simple way<\/li>\n
  • develop fixes and improvements<\/li>\n
  • create a kit for other enthusiasts<\/li>\n
  • develop secondary parts like keyboard and case<\/li>\n
  • document and develop expansions among those launched<\/li>\n
  • \u2026 Learning and having fun with all this adventure.<\/li>\n<\/ul>\n

    In honor of my old TK82c that provided everything else\u2026<\/p>\n

    \"TK82c\"<\/p>\n","protected":false},"excerpt":{"rendered":"

    Probably the youngest don’t now this, but in the early 1980s, there were some personal computer initiatives like Apple II (Apple Computers, 1977), PET (Commodore International, 1977), TRS-80 (Tandy Corporation \/ Radio Shack, 1977) that already dominated the international market. This was made possible by the very first Altair 8800 (Micro Instrumentation Telemetry Systems, 1975) […]<\/p>\n","protected":false},"author":1,"featured_media":4343,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[51,48,53],"tags":[],"class_list":{"0":"post-4365","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","6":"hentry","7":"category-projects","8":"category-retrocomputing","9":"category-zx80-81-en","11":"post-with-thumbnail","12":"post-with-thumbnail-icon"},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/augustobaffa.pro.br\/site\/wp-content\/uploads\/2021\/03\/IMG_20171230_172416_tk82c.jpg","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p45Kmr-18p","jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/posts\/4365","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/comments?post=4365"}],"version-history":[{"count":2,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/posts\/4365\/revisions"}],"predecessor-version":[{"id":4367,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/posts\/4365\/revisions\/4367"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/media\/4343"}],"wp:attachment":[{"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/media?parent=4365"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/categories?post=4365"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/augustobaffa.pro.br\/site\/wp-json\/wp\/v2\/tags?post=4365"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}