doc:cbm:disk:image:g64
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Both sides previous revisionPrevious revisionNext revision | Previous revisionLast revisionBoth sides next revision | ||
doc:cbm:disk:image:g64 [2020/06/01 01:40] – eek | doc:cbm:disk:image:g64 [2020/06/01 01:47] – eek | ||
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There is some controversy over the header gap (#3). Most people assume it | There is some controversy over the header gap (#3). Most people assume it | ||
- | to be 9 bytes of 0x55 characters, but the early 1540/1541 drives used only | + | to be 9 bytes of '' |
8. This caused an write incompatability with the existing 4040 disks of the | 8. This caused an write incompatability with the existing 4040 disks of the | ||
day. In 1541 ROM revision 901225-3 this error was fixed, and now all drives | day. In 1541 ROM revision 901225-3 this error was fixed, and now all drives | ||
- | write out 9 of the 0x55 characters for the gap. The book " | + | write out 9 of the '' |
DOS" | DOS" | ||
corruption happens at a low level when writing to a disk with a header | corruption happens at a low level when writing to a disk with a header | ||
Line 281: | Line 281: | ||
finding sync marks, header blocks and sector blocks. | finding sync marks, header blocks and sector blocks. | ||
- | FIXME | + | - Search for SYNC (at least 10 or more 1 bits) |
+ | - Check for header id after SYNC (GCR '' | ||
+ | - If header, read the remaining 9 header bytes | ||
+ | - Decode header and get sector value | ||
+ | - Search for SYNC again | ||
+ | - Check for data id after SYNC (GCR '' | ||
+ | - If data, read and store with previous header. | ||
+ | - Have we finished reading the track... stop | ||
+ | - Start over | ||
doc/cbm/disk/image/g64.txt · Last modified: 2020/06/01 01:47 by eek