pc8477b National Semiconductor Corporation, pc8477b Datasheet - Page 46
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pc8477b
Manufacturer Part Number
pc8477b
Description
Advanced Floppy Disk Controller
Manufacturer
National Semiconductor Corporation
Datasheet
1.PC8477B.pdf
(54 pages)
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7 0 Reference Section
7 1 MNEMONIC DEFINITIONS FOR PC8477B COMMANDS
BFR
BST
DC0
DC1
DC2
DC3
DENSEL Density Select control bits used in the Mode
DIR
DMA
DR0
DTL
EC
EIS
EOT
ETR
FIFO
FRD
FWR
GAP
HD
IAF
IPS
LOCK
LOW
PWR
Symbol
Buffer enable bit used in the Mode command
Enabled open-collector output buffers
Burst Mode disable control bit used in Mode
command Selects the Non-Burst FIFO mode if
the FIFO is enabled
Drive Configuration 0 – 3 Used to set a drive to
conventional or perpendicular mode Used in
Perpendicular Mode command
command
Direction control bit used in Relative Seek
command to indicate step in or out
DMA mode enable bit used in the Specify
command
Drive Select 0 – 1 bits used in most commands
Selects the logical drive
Data Length parameter used in the Read Write
Scan and Verify commands
Enable Count control bit used in the Verify
command When this bit is 1 the DTL parameter
becomes SC (Sector Count)
Enable Implied Seeks Used in the Configure
command
End of Track parameter set in the Read Write
Scan and Verify commands
Extended Track Range used with the Seek
command
First-In First-Out buffer Also a control bit used in
the Configure command to enable or disable the
FIFO
FIFO Read disable control bit used in the Mode
command
FIFO Write disable control bit used in the Mode
command
Gap2 control bit used in the Perpendicular Mode
command
Head Select control bit used in most commands
Selects Head 0 or 1 of the disk
Index Address Field control bit used in the Mode
command Enables the ISO Format during the
Format command
Implied Seek enable bit used in the Mode Read
Write and Scan commands
Lock enable bit in the Lock command Used to
make certain parameters unaffected by a
software reset
Low Power control bits used in the Mode
command
Description
46
MFM
MFT
MNT
MT
OW
POLL
PRETRK Precompensation Track Number used in the
PTR
PU
R255
RG
RTN
SC
SK
SRT
ST0
ST1
ST2
ST3
THRESH FIFO threshold parameter used in the Configure
TMR
WG
WLD
Symbol
Modified Frequency Modulation control bit used
in the Read Write Format Scan and Verify
commands Selects MFM or FM data encoding
Motor Off Time programmed in the Specify
command
Motor On Time programmed in the Specify
command
Multi-Track enable bit used in the Read Write
Scan and Verify commands
Overwrite control bit used in the Perpendicular
Mode command
Enable Drive Polling bit used in the Configure
command
Configure command
Present Track Register Contains the internal
track number for one of the four logical disk
drives
Pump diagnostic enable bit used in the Mode
command
Recalibrate control bit used in Mode command
Sets maximum recalibrate step pulses to 255
Read Gate diagnostic enable bit used in the
Mode command
Relative Track Number used in the Relative
Seek command
Sector Count control bit used in the Verify
command
Skip control bit used in read and scan
operations
Step Rate Time programmed in the Specify
command Determines the time between step
pulses for seek and recalibrates
Status Register 0 – 3 Contains status
information about the execution of a command
Read in the Result Phase of some commands
command
Timer control bit used in the Mode command
Affects the timers set in the Specify command
Write Gate control bit used in the Perpendicular
Mode command
Wildcard bit in the Mode command used to
enable or disable the wildcard byte (FF) during
Scan commands
Description