Hello Spiro, > That is, the drive code handles a bitmap for every sector of the track. > On start, it reads everything as unread. > > As soon as a sector header arrives under the R/W head, it is read and > decoded. If the sector is not yet read (bit in the bitmap = 0), the > block is read and send over to the PC. > > If the sector was already read, the drive code just waits for the next > sector header and repeats the process, until all blocks are read. Aha, a very good idea! what I knew so far: the 1541 GCRs the data for the wanted sector and then compares it with the data passing under the head. I assumed that there wasn't enough time to read the data first, de-GCR it ( yes Patryk, you were right :) and then check if the sector is the one we want. Or, just popped up, you read the header AND data and then do the de-GCRing of the header? There is only a little misunderstanding between us: 1541IDE has no connection to a PC, it has its own hard disk drive on board. So warp mode is out of the question. I have thought about storing raw data on the disk but that means that I have (de-)GCR it every time I only use the HDD as floppy. Hmmm, just pops up: what about reading the data of a complete track on the HDD and to de-GCR it after reading the complete track? The above idea is not completely original: I already started with building a module to replace the original 2 KB SRAM with a 32 KB one. The idea was to read a complete track into memory and, as said above, to de-GCR it after reading the complete track. But I think now that I prefer the idea using the HDD. Reason: no additional change of the hardware needed. <pause, need to paint some walls> During the painting another idea popped up: combining 1541LPT and 1541IDE. So far I used removable brackets to take the HDD from the 1541 and to place it in a PC. OK, that means adding an extra 6522 to the drive plus a 25-pins male D-connector. (this 6522 takes care of the communication with the PC) The advantage: I can fill the HDD in a much more easier and faster way with data using prooven software. IMHO that is really worth the extra hardware. Regarding the source codes: - the one from Forum64.de has no comments, uses illegal opcodes and is meant to run on a C64. - loader-v146.zip has more than 3 MB of data. Not quite user friendly to have a peek at. - LFT's GCR decoding on the fly': just great! Very good explanation and a well documented source code. This and the various comments of yours made me forget the other two. One idea was to drop the floppy drive from the project again but then I thought that it could come in handy to be able to create an image on the spot. The combination of using the HDD for temporary storage and LFT's GCR decoding make it worth. I just for the fun :) Thank you all for your input! -- Kind regards / Met vriendelijke groet, Ruud Baltissen www.Baltissen.org Message was sent through the cbm-hackers mailing listReceived on 2015-08-24 17:00:07
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