BASF 6106 - Write Protect Oetector

2.2.6 WRITE PROTECT DETECTOR
The write protect detector (Fig. 2-23) is imple-
mented like the index detector. A LED and a
photo
transistor are used with a comparator circuit
to detect the write protect notch in the Flexy
Disk.
When a Flexy Disk with an open notch is
inserted. the photo transistor will sense the
light of the LED causing the negative input pf
the comparator to go low and the output of the
comparator
"NOTCH OPEN" wi 11 be high. The setting
of the write protect jumpers decides. whether
writing is allowed or not (see the following
tabl e).
JUMPER
NOTCH COVERED
JJ3:3-4
unprotected
JJ3:5-6
protected
JJ4:3-4
+SV
KUH DIS/.:.
If WRITE INHIBIT is high, the WRITE ENABLE-signal
is disabled. The mini disk drive is now unable
to write, even if the host system will activate
the WRTGATE/ interface line. The WRITE PROTECT/ -
signal
is sent to the host system when OUTENABLE
is high. The WRITE PROTECT-line informs the host
system,
that a write protected Flexy Disk is in-
serted. If an unproterted Flexy "is~ is inserted,
WRITE PROTECT/ will be inactive and write operations
are
a11owed.
NOTCH OPEN
REMARKS
protected
opt i
ona 1
unprotected
ECMA
",,:':::::: tJ lJ tl' U T INTF.f<.FACE :.:.;.:.;.~:.:.:.:.:.:.:-:-:.:.:.:.:.:.:.:.:.:.:.; .. ; ':-r
I~i
lIorCH ~;
WRITt ~:~ TO
fRorECT I ::; THE
.;. H0sr
WRITE PID!'EL'T NOTCH
OPEN ~ JJ4
V3--
:;; SYSrEM
:::
:;:
::: ~:.:.:.:.:.:.:.:.:.;.;.:.:.:.:,:.~.:.:.:.;.:.:.:.:.:.:.:.;.:.;.:.;.: .:-:. :.:.:.:.:.:-:.:.:.:-:.:.!.:.:.:.:.:-:-;.;.:.;. :.:
F101 HOST SYSTEM
,.:.;,.:.;.:.:.:. I NP U T 1 NTERFACE ;.:.:. ;.;.: .;.:.:-:-:.:.:.:.:;:;:;:::;::::.:.:.:.;.;.:.:<:;
:::
i~l t{;:110 ENA f!! ~~E
·,:i.~ WRTENA :.; 1<11 I TE
;~: CI Re U ITS
t WRITE GATE! ~::
.. ~:
:;: :-:.:.~.:.:.:.:.:.:.:.:.:.:.:.;.:.:.:.:.:.: .:.:.:. :.:.~.:.:.:-:.:.:-:.:.:.:.~.;.:.:.;.:.:.: .:.;.;.:-:.;.:.: :. :-;. :.: .!.: .;.:.;.
FIGURE 2 - 23 WRITE PROTECT DETECTOR
2 - 17