> On Sun, 31 Oct 2010 11:57:27 -0700 > Nate Lawson <email@example.com> wrote: > >> We have been doing some robustness testing of the ZoomFloppy board. It >> uses a 7406 for driving the lines in order to be able to sink a decent >> amount of current to support multiple IEC devices on the bus. >> >> http://www.root.org/~nate/c64/xum1541/ >> >> What is the defined worst-case IEC bus configuration that we should >> support? I'd like a reasonable limit we can support while not adding too >> much delay for users of one or two drives. Just to summarize the discussion: Most people think 4 drives is enough. Some want 6 or 8 devices, including printers. The 7406 total recommended sink current is 40 mA, max is 60 mA. That is 8 or 12 drive-equivalents at 1k ohm, respectively. For 2 lines simultaneously-held (say, CLK & DATA), that allows 4 drives. The max value allows 4 drives and 3 lines (CLK/DATA/ATN, for example). So I believe we can comfortably access 4 drives, given a short enough total cable length and pessimistic enough delays. No one has supplied concrete info about bus characteristics, so we'll have to just go with what we measure for 4 drives and various lengths of cable. -- Nate Message was sent through the cbm-hackers mailing listReceived on 2010-11-03 21:00:09
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