![\"\"](\"docs\/8250\/8250.jpg\")
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4133 blocks free!<\/p>\n
The front says “CBM Model 8250 dual drive floppy disk”.<\/p>\n On the back, there is power and an IEEE-488 port. The model sticker says “DUAL FLOPPY 8250M”. The sticker next to it warns against opening it, but…<\/p>\n …unscrewing just two screws allows the top to be lifted up, similarly to the PET. The digital board is on the top side, and the transformer, the two drives and the analog board on the bottom.<\/p>\n This is drive 1. It’s the original SA-400<\/a> height \u2013\u00a0the later standard 5.25″ bay<\/em>, still used today by CD drives in PC towers, is half of this1<\/a><\/sup>.<\/p>\n Drive 0 is below the analog board, which is responsible for both drives. The two black cables go to the two drive heads, and the wires in the two red plugs go to the mechanics of the two drives.<\/p>\n The digital board is really two computers in one, with two CPUs:<\/p>\n The 4 KB of RAM are shared by both systems.<\/p>\n The first drive systems for the PET (2040\/4040, 1978) were dual-drive, single-sided, with 170 KB per side. The 2031 was a low-cost version with only a single drive and a single CPU. The well-known 1541 is a slightly modified 2031 with a Commodore Serial Bus instead of IEEE-488.<\/p>\n In 1980, Commodore introduced the 8050, which fit 3x as much data on a single side by using twice as many tracks and a higher bitrate<\/a>. The 8250 from 1982 was a dual-sided version of the 8050. A year later, a “low-profile” version (8250LP) was released that was only about half the height.<\/p>\n The SFD-1001, a single-drive version of the 8250LP was introduced in 1985. It looked just like a 1541, but fit 1 MB on the same disks, and had an IEEE-488 port instead of Serial.<\/p>\n Drives with an IEEE-488 connector could be used with a C64 through one of several<\/a> adapter<\/a> cartridges<\/a>.<\/p>\n There were later “LP” (low profile) drives (8250LP, 2031LP) with mechanics half the height. ↩<\/a><\/p>\n<\/li>\n In this device, the RIOTs have the markings “CO 10750”, which is an Atari designation. It seems like these chips were produced for Atari devices like the 2600, but ultimately used by Commodore themselves.↩<\/a><\/p>\n<\/li>\n<\/ol>\n<\/div>\n","protected":false},"excerpt":{"rendered":" The Commodore 8250 was the high-end 5.25″ disk system for the Commodore PET, with two drives that could each fit 1 MB (4133 blocks free) on a standard disk. Here are some high-res pictures. 4133 blocks free! The front says “CBM Model 8250 dual drive floppy disk”. On the back, there is power and an … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,13,30],"tags":[],"class_list":["post-1155","post","type-post","status-publish","format-standard","hentry","category-commodore","category-floppy-disks","category-teardown"],"_links":{"self":[{"href":"https:\/\/www.pagetable.com\/index.php?rest_route=\/wp\/v2\/posts\/1155","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.pagetable.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.pagetable.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.pagetable.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.pagetable.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1155"}],"version-history":[{"count":0,"href":"https:\/\/www.pagetable.com\/index.php?rest_route=\/wp\/v2\/posts\/1155\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.pagetable.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1155"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.pagetable.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1155"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.pagetable.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1155"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n\n
Historical Context<\/h2>\n
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