RL01/RL02
cartidge-based hard disk drive format
RL01 and RL02 drives are moving head magnetic disk drives manufactured by Digital Equipment Corporation for the PDP-8 and PDP-11 microcomputers. The RL01 and RL02 drives stored approximate 5MB and 10MB respectively, utilizing a removable data cartridge. The drives are typically mounted in a standard 19" rack and weigh 34 kg. Up to four RL02 or RL01 drives may be used, in any combination, from a single controller. Typically an RL11 in the case of a Unibus PDP-11 and an RLV11 or RLV12 in the case of a Q-bus PDP-11. On the PDP-8/a the controller is an RL8A which consists of an M8433 Hex wide Omnibus card.
Cartridge format
The RL01 and RL02 data cartridges are based on IBM 5440 cartridges, but have servo tracking data pre-encoded onto the cartridge. This reduces the need for strict head alignment, allowing cartridges to be used in several drives (although there was no backwards compatibility between RL02 and RL01 cartridges, despite similar appearance). However, this prevents on-site low level formatting of cartridges. The drives have logic to prevent this servo data from being overwritten.
“RL01/RL02” enters the record as cartidge-based hard disk drive format. Crown Archives preserves that source wording while asking what RL01, RL02 and cartidge-based can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Apr 6, 2026. The linked authority identifier is Q56291532. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “RL01/RL02” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.