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Youtube copyq12/29/2023 ![]() I did it in two phases, with an initial scan looking for syncs and then subsequently seeking on each one of those and capturing a length of GCR, which was then sent back to the 64. Version 2 was a true nibbler, but the limitations of RAM on the 1541 and the slow speed of the Commodore serial bus presented a challenge in getting an entire track of GCR (group coded recording) bytes back to the C64 host. Version 1 was not a nibbler, it was just very good at handling and reproducing errors. Ours was the best prior to the advent of nibble copying on the C64. The trick was to get those latter errors affecting as few sectors as possible. Some errors were track errors, others were for single sectors, and still others tended to affect groups of sectors. On version 1 could also edit the sector list to add or remove specific errors wherever you wanted on the disk. Obviously we used the RAM which was mapped under the ROM and I/O to maximize the buffer size. ![]() I understand this latter feature especially made it pretty popular at user groups. If the data fit entirely in RAM (as was very often the case) the user was asked if they wanted to make another copy. After formatting, the data were subsequently written out. Version 1 already used this to actually format the target disk with the desired errors, blank sectors or zeroed sectors (there was a difference) on the fly. I wrote the code that ran inside the drive.Īll versions executed code within the 1541 drive’s RAM. I was a co-author of Copy-Q versions 1 and 2, and am familiar with many details of version 3.
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