Re: max IEC bus length and loading?

Date: Sun, 7 Nov 2010 16:24:11 +0100
Message-ID: <>
Quoting Nate Lawson:

> >> 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.

I tried to find characteristics, which is surprisingly difficult.

I came over a book called : "Commodore 1541 Troubleshooting and Repair guide" 
by Michael G. Peltier.
On Page 154, there is a big WARNING not to connect more than 5 drives.
Please check:

I hope that somehow answers your question (albeit in a vague and roundabout 
way, I'm afraid)


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