File:Ferranti Archives ZX81-UNK-NOT-139 Handwritten table of ZX81 memory usage.pdf
Summary
[edit | edit source]A handwritten table titled "ZX81 MEMORY USAGE" on lined paper, in pencil with red-pen tick boxes. For each 4K block from 0K to 60K it gives the state of A15 to A12 and marks whether I/O read and write cycles and memory read and write cycles occur. I/O cycles are marked at every address, memory reads at 0K, 4K, 16K and 48K, and memory writes only at 16K. This fits the ZX81's 8K ROM at 0K to 8K, RAM at 16K and the display being fetched with A15 set at 48K, though the sheet itself does not say so. The 36K row is written "30K" in error. It belongs with the RAM expansion drawings ZX81-UNK-SCH-135, ZX81-UNK-SCH-140 and ZX81-UNK-SCH-141. Part of the Ferranti Archives 2026.
Archive record
[edit | edit source]| Catalogue ID | ZX81-???-NOT-139 |
|---|---|
| Date | Undated |
| Origin | UNKNOWN |
| Document type | Notes |
| Device or subject | ZX81 memory map |
| Catalogue description | A pencil table of "ZX81 memory usage" |
| Original file name | {{{filename|}}}
|
| Found in | ZX81-FER-FOL-142 |
| Pages | 1 |
Source
[edit | edit source]Ferranti Archives 2026, original scan on Google Drive.
Author
[edit | edit source]Unknown
Licence
[edit | edit source]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
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Dimensions | User | Comment | |
|---|---|---|---|---|
| current | 11:00, 18 October 2026 | 0 × 0 (860 KB) | Josh (talk | contribs) | Ferranti Archives 2026: ZX81-UNK-NOT-139 |
You cannot overwrite this file.
File usage
There are no pages that use this file.