gm82c765b ETC-unknow, gm82c765b Datasheet - Page 17

• Manufacturer Part Number: gm82c765b
• Description: Floppy Disk Subsystem Controller
• Manufacturer: ETC-unknow

The eight-bit data Register stores data, comma-
nds, parameters, and FDD status information.
Data bytes are read out of, or written into, the
Data Register in order to program or obtain the
results after a particular command.
TABLE 7. MASTER STATUS AND DATA REGISTERS Relationships
* OPERATIONS REGISTER
The Operations Register provides support logic
that latches the data bus upon receiving
when this happens. The Operations
Register replaces the typical latched port found
.
TABLE 8. OPERATIONS REGISTER
LDOR
* DATA REGISTER
OR0
OR1
OR2
OR3
OR4
OR5
OR6
OR7
A0
0
0
0
1
1
1
ad
WR
DMAEN
MOEN1
MOEN2
(MSEL)
DSEL
(X)
(X)
. CS should not be active
SRST
RD
0
1
0
0
0
1
: Drive Select, if low and MOEN1 = 1, then
: In GM82C765B this mist be logic 0 for
: Soft reset, active low.
: DMA enable, active in Special and PC AT modes, Qualifies DMA and IRQ
: Motor On enable, inverted output
: Motor On enable, inverted output
: Has no defined function. A spare.
: Mode Select, During a soft reset condition, may be used to select
outputs and DACK input.
between Special mode (1) and PC AT mode (0).
MOEN2 = 1, then
No defined function in GM82C765B.
1
0
0
0
1
0
WR
DS
2
17
is active, but only in the PC AT mode
The relationship between the Master Status
Register and the Data Register Status Register
and the Data Register and the signals
in floppy subsystems used to control disk drive
spindle motors and to select the desired disk
drive. Table 8 represents the operations
Register
RD
Read Main Status Register
ILLEGAL
ILLEGAL
ILLEGAL
READ from DATA REGISTER
WRITE into DATA REGISTER
,
WR
MO
MO
, and A0 are shown in Table 7.
1
2
DS and
is active only in PC AT
is active in PC AT
FUNCTION
1
DS
1
is active. If high and
DS
2
to become active.
GM82C765B