Sharp MZ-80B Service Manual page 65

Terminlt
Terminal Name
Symbol
I/O
No.
38 DATA REQUEST
DRQ 0
39
INTERRUPT IRQ 0
REQUEST
Floppy Interface
15 STEP
STEP 0
16 DIRECTI.ON
DIRC 0
17
EARLY EAR>LY 0
.
18 LATE LATE
0
22 TEST
TEST I
23 HEAD LOAD
HLT
I
TIMING
25 READ GATE RG
0
26 READ CLOCK RCLK I
27 RAW READ RAW I
READ
28
HEAD LOAD HLD 0
29
ITRACK GREATER
TG43
0
THAN 43
30 WRITE GATE WG
0
31 WRITE DATA
WO 0
32 READY READY I
33 WRITE FAULT
WF
I
34
TRACK 00
TROO I
35 INDEX PULSE IP I
36 WRITE PROTECT
WRPT
I
37 DOUBLE DENSITY DDEN I
40 NON CONNECTION NC
1
Explanation of Functions
It is the open drain output and, when DRQ ~
1, it indicates byte data accumulated in OR
in case of read-out. In case of write-in, OR is empty and it indicates a demand for data.
DRQ is reset through the function of write-in or 'read-out. Connect a 10Kfl. blew up
resistance.
It is the open drain output and with generation of command end, stop or interruption of
type IV command, IRQ
~
1. It is reset with the write-in of the following command or
read-out of STR. Blew up resistance is 10Kfl..
The step output generates a step pulse for moving the head. There is 1 pulse for 1 step.
It is the terminal showing the direction 'of head movement. With DIRC ~ 0, the head moves
outward and with DIRC - 1 the liead moves inward.
It is the output terminal for write preconvention and .when EARL Y ~ 1 it indicates that
serial data output from WO should be shifted faster .
It is the output terminal for write preconvention and when LATE
~
1 it indicates that serial
data output from WO should be shifted slower.
Input terminal used only for chip testing. (When TEST
~
0, delay due to the inner timer
is ignored) The user should connect this terminal to 5V or leave it open.
It is the settle input signal for the head after a head load command (HLD
~
1). It engages
when HLT
~
1.
With Ru 1, it informs the external data separator of a check of the field only when FDC
is 0 (in case of FM) or of the field only when it is 0 or 1 (in case of MFM). It is the signal
for takinQ this simultaneouslv.
This is a signal for making a window in the data. It is developed in response to external data
flow and is input on the FDC §ide. Related to RAW READ, rising and falling is important
but level (high or low) is not important.
This is raw data directly input from the disk drive. It is used when receiving a signal and
data is indicated by a negative pulse.
It is the output terminal for controlling whether the head ,is pressed down to the media or
not. The head is pressed down to the media when H LD ~ 1. The head is separated when
HLD ~ O.
It indicates that the head is positioned from track 44 to 76 when TG43
=
1.
It indicates that it is from track 00 to track 43 when TG43
~
O. This output signal is
effective only at the time of read/write commands.
Output indicating that data is being written into the disk. It indicates data write-in when
WG
=
1.
It is an output for read-in data to the disk. Pulse width for MFM is 250ns and for FM it is
500ns. Both data and address mark are output together at the same time in the case of both
FM and MFM.
It indicates that the disk drive is ready for operation when READY
=
1 and read/write
operations are performed. When READY
=
0, it indicates that the disk drive is not ready
for operation, read/write operations are not performed and IRQ
=
1. Namely, seek is
carried out without reference to the READY condition. It indicates the polarity of the
READY input is inverted to STR 7.
It is the input for trouble checks during write-in to the disk. It indicates an error during
write-in when WF
=
O. The write command is stopped and the WRITE FAU LT status bite
set.
Input indicating whether the head position is in track 00 or not. It indicates track 00 is
being checked when TROO
~
O.
Input indicating that the in~x pulse of the disk is being checked. It indicates the index
pulse is being checked when IP
=
O.
Input indicating that write-in to the disk is forbidden. When a write command is started,
generally WPRT is sampled and if WPRT
=
0 the command is stopped and WR ITE PRO-
TECT status bite is set.
This input is for selection of single or double density operation.
Double density is selected when DD EN
=
0 and single when DDEN
=
1.
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