{"id":34749,"date":"2025-04-11T20:00:00","date_gmt":"2025-04-11T18:00:00","guid":{"rendered":"https:\/\/www.jungsi.de\/?p=34749"},"modified":"2026-08-27T21:59:14","modified_gmt":"2026-08-27T19:59:14","slug":"commodore-1750-commodore","status":"publish","type":"post","link":"https:\/\/www.jungsi.de\/en\/commodore-1750-commodore\/","title":{"rendered":"Commodore 1750 [Commodore 64\/128]"},"content":{"rendered":"<p class=\"wp-block-paragraph translation-block\">In this article, I am revisiting an item from my collection that I haven't showcased before: the Commodore 1750 module. This piece of hardware has the abbreviation <strong>REU<\/strong>, which stands for <strong>RAM Expansion Unit<\/strong>, and was a memory expansion for the Commodore computers <strong>C64<\/strong> and <strong>C128<\/strong>.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">History of creation and publication<\/h5>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">The Commodore 1750 was presented for the first time at the CES (Consumer Electronics Show) in Chicago in 1985. A specific release date and the start of availability need to be researched in more detail, but it is known that the hardware came onto the market relatively soon after the launch. The REU series was created in response to the growing need for additional memory for the home computers that were popular at the time.<\/p>\n\n\n\n<!--more-->\n\n\n\n<h5 class=\"wp-block-heading\">Differences between the versions<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">The REU is available in three configuration levels:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Commodore 1700<\/strong> with 128 KB (price: 199 DM).<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Commodore 1764<\/strong> with 256 KB, specifically for the C64.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Commodore 1750<\/strong> with 512 KB, the most powerful variant.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">The 1700 and 1750 versions were primarily intended for the <strong>C128<\/strong>, but could also be used with the <strong>C64<\/strong>. However, when used on the C64, a more powerful power supply was required due to the increased power consumption. The REU 1764, which was developed specifically for the C64, was therefore delivered directly with an adapted power supply (C128 power supply with plug for the C64).<\/p>\n\n\n\n<p class=\"wp-block-paragraph translation-block\"><strong>Technical similarities:<\/strong> All expansion modules are identical in design; only the size and number of memory chips differ.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss-1024x768.jpg\" alt=\"1750 REU - Anschluss\" class=\"wp-image-36057\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss-1024x768.jpg 1024w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss-300x225.jpg 300w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss.jpg 1400w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">1750 REU \u2013 Connection<\/figcaption><\/figure>\n<\/div>\n\n\n<h5 class=\"wp-block-heading\">Technical details<\/h5>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">Unfortunately, the Commodore 1750 could not simply be used as additional addressable RAM. The reason for this lies in the limitations of the <strong>6510 processor<\/strong>, which can address only <strong>64 KB of RAM<\/strong>. Instead, the REU\u2014utilizing the <strong>REC (RAM Expansion Controller)<\/strong>, a specialized chip\u2014enabled the rapid exchange of data between main memory and the REU via <strong>DMA (Direct Memory Access)<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">For programs to utilize the hardware, they had to be equipped with appropriate routines. One example of this is <strong>GEOS<\/strong>, which used the REU as an external RAM disk. The <strong>C128<\/strong>, in particular, offered expanded capabilities, as <strong>BASIC V7.0<\/strong> included the commands <strong>FETCH<\/strong>, <strong>STASH<\/strong>, and <strong>SWAP<\/strong> for directly accessing the REU. However, even in this case, the memory could not be used directly for BASIC.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">Potential applications at the time<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">The REU was primarily developed for memory-intensive applications. Examples include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>GEOS<\/strong>: Use as a RAM disk for faster operation.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>CP\/M 3.0 on the C128<\/strong>: Some versions recognized the REU and could mount it as a fast RAM drive (drive letter <strong>M:<\/strong>).<\/li>\n\n\n\n<li class=\"translation-block\">Programmers used the REU for their own routines in assembly language.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Games and Demos<\/strong>: Some ambitious developers were able to use the REU to achieve impressive graphical effects or faster loading times.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" data-id=\"36055\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-deutsch-768x1024.jpg\" alt=\"1750 REU - Anleitung deutsch\" class=\"wp-image-36055\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-deutsch-768x1024.jpg 768w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-deutsch-225x300.jpg 225w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-deutsch.jpg 1050w\" sizes=\"auto, (max-width: 768px) 100vw, 768px\" \/><figcaption class=\"wp-element-caption\">1750 REU &#8211; Anleitung deutsch<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" data-id=\"36056\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-englisch-768x1024.jpg\" alt=\"1750 REU - Anleitung englisch\" class=\"wp-image-36056\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-englisch-768x1024.jpg 768w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-englisch-225x300.jpg 225w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anleitung-englisch.jpg 1050w\" sizes=\"auto, (max-width: 768px) 100vw, 768px\" \/><figcaption class=\"wp-element-caption\">1750 REU &#8211; Anleitung englisch<\/figcaption><\/figure>\n<\/figure>\n\n\n\n<h5 class=\"wp-block-heading\">Today's possibilities with the 1750<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Nowadays, the REU can still be put to a wide range of uses, particularly by retro-computing enthusiasts:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\">Use with emulators such as <strong>VICE<\/strong> that virtually replicate REU functions.<\/li>\n\n\n\n<li>Utilization by modern tools that fully exploit the REU's DMA function.<\/li>\n\n\n\n<li class=\"translation-block\">Hardware expansion: It is theoretically possible to upgrade the 1700 and 1764 models to <strong>512 KB<\/strong> by replacing or adding memory chips. Furthermore, capacities of <strong>up to 2 MB<\/strong> are realistic and feasible. However, with more than 512 KB of memory, the REU is no longer 100% compatible.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">One example of alternative memory expansions is the <strong>GeoRAM (512 KB)<\/strong>, developed by <strong>Berkeley Softworks<\/strong> as a successor to the REU for GEOS. Nevertheless, the original REU was faster and more versatile due to its DMA access.<\/p>\n\n\n\n<div class=\"wp-block-jetpack-slideshow aligncenter\" data-autoplay=\"true\" data-delay=\"5\" data-effect=\"fade\"><div class=\"wp-block-jetpack-slideshow_container swiper\"><ul class=\"wp-block-jetpack-slideshow_swiper-wrapper swiper-wrapper\"><li class=\"wp-block-jetpack-slideshow_slide swiper-slide\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" alt=\"1750 REU - Anschluss\" class=\"wp-block-jetpack-slideshow_image wp-image-36057\" data-id=\"36057\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss-1024x768.jpg\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss-1024x768.jpg 1024w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss-300x225.jpg 300w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Anschluss.jpg 1400w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-block-jetpack-slideshow_caption gallery-caption\">1750 REU \u2013 Connection<\/figcaption><\/figure><\/li><li class=\"wp-block-jetpack-slideshow_slide swiper-slide\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" alt=\"1750 REU - Metallk\u00e4fig\" class=\"wp-block-jetpack-slideshow_image wp-image-36059\" data-id=\"36059\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Metallkaefig-1024x768.jpg\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Metallkaefig-1024x768.jpg 1024w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Metallkaefig-300x225.jpg 300w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Metallkaefig.jpg 1400w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-block-jetpack-slideshow_caption gallery-caption\">1750 REU &#8211; Metallk\u00e4fig<\/figcaption><\/figure><\/li><li class=\"wp-block-jetpack-slideshow_slide swiper-slide\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" alt=\"1750 REU - Platine\" class=\"wp-block-jetpack-slideshow_image wp-image-36061\" data-id=\"36061\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-768x1024.jpg\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-768x1024.jpg 768w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-225x300.jpg 225w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine.jpg 1050w\" sizes=\"(max-width: 768px) 100vw, 768px\" \/><figcaption class=\"wp-block-jetpack-slideshow_caption gallery-caption\">1750 REU &#8211; Platine<\/figcaption><\/figure><\/li><li class=\"wp-block-jetpack-slideshow_slide swiper-slide\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" alt=\"1750 REU - Platine - Unterseite\" class=\"wp-block-jetpack-slideshow_image wp-image-36060\" data-id=\"36060\" src=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-Unterseite-768x1024.jpg\" srcset=\"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-Unterseite-768x1024.jpg 768w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-Unterseite-225x300.jpg 225w, https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Platine-Unterseite.jpg 1050w\" sizes=\"(max-width: 768px) 100vw, 768px\" \/><figcaption class=\"wp-block-jetpack-slideshow_caption gallery-caption\">1750 REU &#8211; Platine &#8211; Unterseite<\/figcaption><\/figure><\/li><\/ul><a class=\"wp-block-jetpack-slideshow_button-prev swiper-button-prev swiper-button-white\" role=\"button\"><\/a><a class=\"wp-block-jetpack-slideshow_button-next swiper-button-next swiper-button-white\" role=\"button\"><\/a><a aria-label=\"Pause Slideshow\" class=\"wp-block-jetpack-slideshow_button-pause\" role=\"button\"><\/a><div class=\"wp-block-jetpack-slideshow_pagination swiper-pagination swiper-pagination-white\"><\/div><\/div><\/div>\n\n\n\n<h5 class=\"wp-block-heading\">Conclusion<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">The Commodore 1750 was an impressive piece of hardware for its time, offering the C128 and C64 entirely new possibilities\u2014ranging from faster load times to expanded memory applications. Although its utility was limited back then, today's retro community demonstrates the true potential of this expansion.<\/p>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">I received my 1750 REU with English and German manuals. The previous owner used a <strong>C128 primarily with GEOS<\/strong>, which remains one of the most popular applications for the REU to this day.<br><\/p>\n\n\n\n<h5 class=\"wp-block-heading\">Links<\/h5>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">Current software with REU support:<br>SONIC The Hedgehog for C64\/C128<br><a href=\"http:\/\/spacetaxi.epizy.com\/CBM-REU-GAMES\/REU-GAMES.htm?i=1\" target=\"_self\">Commodore 64 REU Games, CBM 1700 REU, CBM 1750 REU, CBM 1764 REU<\/a><br><a href=\"https:\/\/www.lemon64.com\/games\/details.php?id=3763\" target=\"_self\">Metal Warrior 4: Agents of Metal<\/a><br><a href=\"https:\/\/www.retro-programming.de\/retro-welt-2\/hardware\/meine-altertumlichen-geratschaften\/c64\/module\/ram-expansion-unit-reu\/\" target=\"_self\">RAM Expansion Unit (REU): Up to 16MB for the C64<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>In diesem Artikel greife ich mit dem Modul Commodore 1750 wieder ein St\u00fcck aus meiner Sammlung auf, das ich bisher noch nicht vorgestellt habe. Dieses \u2026<\/p>","protected":false},"author":2,"featured_media":32207,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false,"_links_to":"","_links_to_target":""},"categories":[115],"tags":[682,4843,4737],"class_list":["post-34749","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-c64","tag-commodore","tag-englisch-verfuegbar","tag-hardware"],"wp-worthy-pixel":{"ignored":false,"public":"565b24e138bc4386be4b8a224b638da1","server":"","url":"https:\/\/vg04.met.vgwort.de\/na\/565b24e138bc4386be4b8a224b638da1"},"wp-worthy-type":"normal","jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/www.jungsi.de\/blog\/wp-content\/uploads\/1750-REU-Oben.jpg","_links":{"self":[{"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/posts\/34749","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/comments?post=34749"}],"version-history":[{"count":1,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/posts\/34749\/revisions"}],"predecessor-version":[{"id":42517,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/posts\/34749\/revisions\/42517"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/media\/32207"}],"wp:attachment":[{"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/media?parent=34749"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/categories?post=34749"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jungsi.de\/en\/wp-json\/wp\/v2\/tags?post=34749"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}