Difference between revisions of "GEOS Protection"
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(Created page with "On track 21 in the header trail and sector trail the trail has to end with 55 67 55 55 67. Header trails are checked for sector 0 - 18, sector trails for sector 0 to 17 (track...") |
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− | On track 21 in the header trail and sector trail the trail has to end with 55 67 55 55 67. | + | On track 21 in the header trail and sector trail the trail has to end with 55 67 55 55 67 before the following sync. |
Header trails are checked for sector 0 - 18, sector trails for sector 0 to 17 (track trail after last sector is not checked). | Header trails are checked for sector 0 - 18, sector trails for sector 0 to 17 (track trail after last sector is not checked). | ||
+ | |||
+ | Example from GEOS 2.5: | ||
+ | ... | ||
+ | sync 33 | ||
+ | ; header | ||
+ | gcr 08 | ||
+ | begin-checksum | ||
+ | checksum 13 | ||
+ | ; sector | ||
+ | gcr 00 | ||
+ | ; track | ||
+ | gcr 15 | ||
+ | ; id2 | ||
+ | gcr 4a | ||
+ | ; id1 | ||
+ | gcr 4c | ||
+ | end-checksum | ||
+ | gcr 0f | ||
+ | gcr 0f | ||
+ | ; Trk 21 Sec 0 | ||
+ | bytes 55 55 '''55 67 55 55 55 67''' | ||
+ | bits 111111 | ||
+ | sync 34 | ||
+ | ; data | ||
+ | gcr 07 | ||
+ | begin-checksum | ||
+ | gcr 15 08 ... | ||
+ | checksum 76 | ||
+ | end-checksum | ||
+ | gcr 00 | ||
+ | gcr 00 | ||
+ | bytes 55 55 '''55 67 55 55 55 67''' | ||
+ | bits 111111 | ||
+ | sync 34 | ||
+ | ; header | ||
+ | ... | ||
There is an extensive description at [https://www.c64-wiki.de/wiki/GEOS-Kopierschutz GEOS protection (german)] | There is an extensive description at [https://www.c64-wiki.de/wiki/GEOS-Kopierschutz GEOS protection (german)] |
Latest revision as of 22:02, 11 January 2021
On track 21 in the header trail and sector trail the trail has to end with 55 67 55 55 67 before the following sync. Header trails are checked for sector 0 - 18, sector trails for sector 0 to 17 (track trail after last sector is not checked).
Example from GEOS 2.5:
... sync 33 ; header gcr 08 begin-checksum checksum 13 ; sector gcr 00 ; track gcr 15 ; id2 gcr 4a ; id1 gcr 4c end-checksum gcr 0f gcr 0f ; Trk 21 Sec 0 bytes 55 55 55 67 55 55 55 67 bits 111111 sync 34 ; data gcr 07 begin-checksum gcr 15 08 ... checksum 76 end-checksum gcr 00 gcr 00 bytes 55 55 55 67 55 55 55 67 bits 111111 sync 34 ; header ...
There is an extensive description at GEOS protection (german)
Pages that refer to this protection
- GEOS DeskPack (← links)
- Descriptions of old disk copy protections (← links)
- GEOS GeoPublish (← links)
- GEOS 64 2.5 (← links)
- GEOS GeoCalc C128 (← links)
- GEOS GeoCalc C64 (← links)
- GEOS GeoFile (← links)
- GEOS GeoFile C128 (← links)
- GEOS 64 2.01 (← links)
- GEOS 128 2.01 (← links)
- GEOS 64 2.0 (← links)
- GEOS GeoWrite Workshop (← links)
- GEOS GeoWrite Workshop 128 (← links)