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Romconfigufation; 8255 Programmable Peripheral Interface - Sharp MZ-800 Service Manual

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MZ-800
4-2-10.
ROM
configuration
The MZ-700 monitor, character generator (eG), MZ-800
monitor, and IPL are implemented on a single chip of
16k x 8-bit ROM.
ROM add ....
soooo
$1000
$2000
$3000
$3FFF
,..-------. $0000
MZ-700
monitor
~----~
$1000
CG
MZ-800
IPL & monitor
4-3. 8255 Programmable Peripheral Interface
The 8255 has three pairs of 8-bit lID ports, each one can
be assigned to input or output port by means of
programming. A different mapping is established de-
Port name (address)
Pin No.
110
Active state
PAo
H
PA,
H
PA
PA2
H
( 700 $EOOO )
PA3
0
H
800 $DO
I
PA.
L
PAs
L
PA7
I
L
PBo
L
PB,
PB
PB2
( 700 $EOOl )
PB3
I
800 $Dl
PB.
I
PBs
PB.
+-
PB7
L
1-------
PCo
0
L
PC,
0
I
- -
PC
INOTE-'I
PC2
0
L
( 700 $E002 )
PC3
0
~TE-21
800 $D2
Pc.
I
H
PCs
I
--
PC.
I
--
PC7
I
- -
--
( 700 $E003 )
--
--
800 $D3
--
NOTE-l: Output data dependent on the bit set mode.
I
Mapping address
Not used
QD-IOCS
FD
IPL & monitor
QD command
BASIC 10CS
Version
$Eooo
$E010
$ESOO
(start address)
$F400
$FFFO
SFFFF
pending on the mode. In the MZ-700 mode, it is {In
memory space, and in the MZ-800 mode, it is on lID
space.
Function
}Keyb~'d ~'"
"mbe
Joystick-l strobe
Joystick-2 strobe
CRT cursor blink timer reset
Keyboard scan input
J
Prohibits sound output of the 8253
Cassette write data
Disables timer interrupt
Rotates the cassette motor
Checks the cassette motor
Cassette read data
CRT cursor blink timer input
Vertical blink signal
Control port
NOTE-2: Motor is controlled on and off by the rising edge of the signal.
27

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