RE: 1541-II write indicator LED
Date: 2002-02-01 12:51:53

Hallo Marko, Piotr,

Studying the SCH of the 1541-II (1541-II.340503.gif on FUNET) there only 4
lines running to U12, the R/W Amplifier:
1- PowerOn
2- Read Data
3- Write Data
4- EG/NG ???

We can skip the first one. If we assume that 2 and 3 are the datastreams
from/to the head, then 4 must be the signal telling U12 that there is a read
or write action going on.
If 4 has another meaning, then output 3 of U11 can be used. This output
delivers the pulses to be send to the haed IMHO. An extra buffer plus the
LED could show us these pulses. If the pulses are to short, one can add a
mono-stable multivibrator like the 74LS221 that enables the LED to light
longer then the actual pulse.
   / __|__
  / /  |_/     Groetjes, Ruud
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