File:Ferranti Archives ZX81-FER-NOT-104 detail, ZX81 ULA tape input and video output circuits.png
Summary
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Pencil sketch headed "ZX81." of two pin circuits of the Sinclair ZX81 ULA. Top: the TAPE IN input on pin 20 (series capacitor, clamp diodes to 5 V and ground, 400 ohm series resistor, 5K to a 0.9 V rail, 16K collector load, emitter follower to the internal CML logic). Bottom: the three-level TV/TAPE output on pin 16 (VIDEO and SYNC inputs, emitter follower with 1K to ground, 200 ohm series resistor to the pin), with the levels written beside it: white 4 V, black 2.8 V, sync 0 V. A faint unlabelled pencil mark sits at the bottom left. The sheet is undated and unsigned.
Detail rendered from File:Ferranti Archives ZX81-FER-NOT-104 Pencil sketch of ZX81 ULA tape input and video output circuits.pdf: cropped to the drawn area and reduced to 1500 pixels wide. Used on Sinclair ZX81 ULA.
Licence
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Ferranti Archives 2026: source and terms of use
This scan is part of the Ferranti Archives 2026, a collection of Sinclair-related documents from Ferranti's files, catalogued in 2026 and released through the Happy Little Diodes YouTube channel (video, catalogue). The archive presents the documents for preserving and archiving material of historical interest, and for non-commercial, educational and archival research. Its terms state that consent is strictly limited to non-commercial use, and that any commercial exploitation of the documents or their contents, including use in connection with the manufacture, marketing or sale of goods, is strictly prohibited by Sky UK Limited.
Copyright remains with the rights holders. The file is not freely licensed and is hosted here for preservation and repair reference only, under the archive's terms. Personal information was redacted by the archive before release; if you find any that remains, please tell [email protected].
File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 11:36, 18 October 2026 | | 1,500 × 2,010 (1.28 MB) | Josh (talk | contribs) | Upload for Sinclair ZX81 ULA / Sinclair ZX Printer pages (W5) |
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