Hallo Didier, > Double PC/XT 9 80 2 720 Kio 250 kbit/s > Haute AT 18 80 2 1 440 Kio 500 kbit/s > > I dont remember the exact details but the speed of the data is > probably twice 9 sectors * 512 bytes/sector * 6 rev/sec * 8 bits = 221184 bits/sec IMHO the number is even a bit too low. 221184 bits/sec = 27648 bytes/sec = 36 uS/byte which isn't a suprise. Although a 720 KB is roughly four times a 1514 (after GCR), it also has twice the number of sides and tracks. These numbers tell us that even a 1 MHz 6502 can handle a 720 KB drive. More interesting: using the same argument, a 2 MHz 6502 should be able to handle a 1.44 MB drive. Why didn't I find this out myself before? Because I did those calculation before but forgot about the two sides and got numbers twice as they should be :( AFAIK it is just a matter of swapping two wires so one can use a PC 720 KB drive on a 1581. Never having had the need for it, I never tried it out myself. Being able to connect a 720 KB drive, a 1.44 MB one shouldn't be a problem either. Next thing: what about the density? The 1.44 FDD has a switch inside that tells the controller whether a 720 KB or a 1.44 MB floppy has been inserted. If I am correct, pin 2 of the Shugart bus is used to give the FDC this information. In the 1581 this pin is connected to the 8520 so it can be read. So are there more bears on the road that could stop us to connect a 1.44 MB FDD to a 1581 and use it? -- ___ / __|__ / / |_/ 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 listReceived on 2012-05-03 07:00:04
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