Sharp PC-1500 - Page 27

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All and more about Sharp PC- 1500 at http:/lwww.PC-1500.info
2-3-5. BF flipflop
The CPU has t\\O supplil-:. of power: VCC and VGG. k the l:lFflipflop i,dri\cn b} VGG.
th<.' st ate of the BF nipflop i~ retained as long as VGG is in 5upply. C\Cn if VCC ;u p ply is
out. The BF flipflop i; ;ct when the BF I input is turned from low to high lc\cl and reset
when t he OFF in struction is issue d fro m t he CP U.
Low state of signal is on th t: BF flipflop output HFO when til e fli pflop is act ive and high
st ate uf sig nal when inac ti ve.
r-------- -- ---------- ·------- --- -,
A
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I
v-
I
I
I
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.-- SS
Q
I
CPU lOCIC
I
O ff
R
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Q -- ---i..n ero
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C NO
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L ---- -- ----- --- ---
- - - - - - -
____ _ __ J
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en
It is possible to comprise a memory back up system using th is BF flipflop.
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