From: Baltissen, GJPAA (Ruud) (ruud.baltissen_at_abp.nl)
Date: 2003-12-09 10:20:21
Hallo Nick, I'm sorry for the late answer but I accidently moved it to the wrong map and only just noticed it. > With 64HDD I have found you need to have support for 16channels > (secondary addresses) for each device number, and keep track of all. That's exactly what I do with CBM-HD as well. > On the serial bus this is done by holding the DATA line active (low) and > the C64 won't be able to send any new instructions until the internal > operation is done, and the line freed I have thought about this as well but the problem is that you then block _all_ communication. With two 1541s the program 10 open 1,8,15,"v0" 20 open 1,9,15,"v0" will let the Validate happen at almost the same time on both the drives. But if device 8 is your PC and it lowers DATA, line 20 won't be executed until the first Validate is done. I noticed this behaviour when having both my PC and 1001 connected to my 8032. But your remark is still helpfull because it made me rethink things again. And I came up with the following idea: I don't use the interrupt at this moment. But using it enables me to check ATN independant of any action the PC is performing. So for example when an ATN occurs during a Validate, I can read the byte telling me what device the command is meant for. If it is one not supported by the PC, I can ignore it and the rest. If it indeed is supported, I can block any further communication by lowering DATA, or in my case NRFD. > ... The parallel IEC bus would have a similar "hold-off" method, > just not sure which signal line is used.... NRFD, Not Ready For Data -- ___ / __|__ / / |_/ Groetjes, Ruud \ \__|_\ \___| <http://Ruud.C64.org> http://Ruud.C64.org =====DISCLAIMER================================================================= 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. 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 its 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. Message was sent through the cbm-hackers mailing list
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