Date: 2009-01-26 08:15:50
Hallo Jim, > http://www.zimmers.net/anonftp/pub/cbm/manuals/drives/1541-manual.txt.gz , Quite obvious place to look, why didn't I think of it? Anyway many thanks! > Why is the number limited to 6: Hmm, indeed hard coded, but not the way I expexted. > I implemented REL file support on uIEC ..... Maybe I can tell you how I implemented it in CBM-HD, the project where a PC emulates an IEEE-drive. I must have read the info you gave me years ago and knew that 'only 720 records' was too limited for a 8x50 drive. My first version was quite simple. The idea behind it was that if I needed record X, I simply had to start at the first sector and the go through all successive sectors, using the T/S info at the beginning of a sector, until I hit the right sector. This is undoable on a mechanical drive because of the unacceptable time delay caused by the mechanical drive. But doable for an harddisk. My second and final version makes use of side sectors (SS) but in a completely different way then the 1541 does. Each SS can be succeeded by another one; the first two bytes contain the T/S info of this successor, just like with SEQ and PRG files. And each SS contains the pointers to 127 records. For example: needing to check the 1000th record now you only need to read 5 sectors instead original 1000 (assuming the record length = 254). Is this 1541, 4040, 8x50 (or whatever) compatible? Surely not! But All REL files related software I encounterd so far worked fine. > Howver, if you're adding this to a list of things to do, I would > put it *way* down on the priority list. I will. After reading the info you gaved me and remembering how I did it in CBM-HD, I was tempted to give it a go, but only for a few moments. Although I'm working with the 1541 sources for many months, I only understand a small part of it. For example I know where the P command for relative files stores its data but I have no idea where the routines that create the records read this data. How can I expect to change software if I don't understand it? But AFAIK you wrote your kernal from scratch on and therefore you're not limited by original routines. So I wish you success and luck with your work !!! -- ___ / __|__ / / |_/ Groetjes, Ruud \ \__|_\ \___| URL: Ruud.C64.org De informatie in dit e-mailbericht is vertrouwelijk en uitsluitend bestemd voor de geadresseerde. Wanneer u dit bericht per abuis ontvangt, verzoeken wij u contact op te nemen met de afzender per kerende e-mail. Verder verzoeken wij u in dat geval dit e-mailbericht te vernietigen en de inhoud ervan aan niemand openbaar te maken. Wij aanvaarden geen aansprakelijkheid voor onjuiste, onvolledige dan wel ontijdige overbrenging van de inhoud van een verzonden e-mailbericht, noch voor daarbij overgebrachte virussen. APG Algemene Pensioen Groep NV is gevestigd te Heerlen en is ingeschreven in het handelsregister van de Kamer van Koophandel Limburg onder nummer 14099617 The information contained in this e-mail is confidential and may be privileged. It may be read, copied and used only by the intended recipient. If you have received it in error, please contact the sender immediately by return e-mail; please delete in this case the e-mail and do not disclose it's contents to any person. We don't accept liability for any errors, omissions, delays of receipt or viruses in the contents of this message which arise as a result of e-mail transmission. APG Algemene Pensioen Groep NV is registered in the trade register of the Chamber of Commerce Limburg, The Netherlands, registration number: 14099617 Message was sent through the cbm-hackers mailing list
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