MCCONFIG(F) XENIX System V MCCONFIG(F)
Name
mcconfig - Irwin tape driver parameters.
Description
/etc/default/mcconfig contains information on Irwin tape
driver parameters. mcconfig entries are in the following
format:
variable=parameterlist
variable is a case insensitive character string that names a
configuration parameter. parameterlist is a string of one
or more parameter values, in formats that vary depending on
the variable used.
The following variables are defined:
IROPT driver options
IRDBG debugging aids
SYSFDC system floppy controller parameters
ALTFDC alternate controller parameters
4100 Irwin 4100 PC bus controller parameters
4100B second 4100 PC bus controller parameters
IRDRV drive searching sequence (old method 2.00)
IRSRCH drive searching sequence (new method 2.02)
4251 4251 address
When configuring parameters, space and tab characters can
not be used. For example,
irdrv=3 is correct, while
irdrv = 3 is incorrect and will be ignored.
Parameters are passed to the tape driver by the daemon
program /etc/mcdaemon. Configuration parameters are given on
separate lines. The pound sign character (#) may be used
open a comment. Comments are terminated by a newline. For
example the mcconfig file might contain:
# this is a comment in the mcconfig file
iropt=F
4251=31f
Changes made to the mcconfig file do not take effect until
the system is rebooted.
IROPT: Configuration Option String
The tape driver configuration variable IROPT may be used
override certain default or automatically determined
configuration parameters. Multiple values can be specified,
for example:
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MCCONFIG(F) XENIX System V MCCONFIG(F)
iropt=Bdf
The values for IROPT are as follows:
B/b: 64K DMA Boundary Present/Absent
B This computer's hardware architecture has a 64K DMA
memory boundary. Tape data transfer buffers may not
cross a 64K physical boundary. This is the case for
most PC and AT compatible machines.
b This computer's hardware architecture does not have a
64K DMA physical memory boundary. Tape data transfer
buffers may be allocated any where in memory. This
is true for PS/2s with the Micro Channel
Architecture.
When neither (B) nor (b) is set, configuration is based upon
the result of Micro Channel presence determination (see the
M/m option). In a Micro Channel machine, (b) is assumed,
otherwise (B) is used.
D/d: Use Demand/Single Byte DMA with Controllers Having a
FIFO
D When running in PC or AT class machine and using a
controller which has a first-in-first-out (FIFO)
buffer, use demand mode DMA transfers. Both the Intel
82072 and 82077 floppy controller chips (the later is
used in the 4100PC) have a 16 byte FIFO.
d When running in a PC or AT class machine use the
standard single byte DMA transfer mode regardless of
the floppy controller type.
When neither (D) nor (d) is set, automatic configuration
determines whether a floppy controller chip with a FIFO is
present on a per controller basis. When a controller having
a FIFO is found (e.g., Intel 82072/82077 parts return a
positive response to the CONFIGURE command), DMA transfers
with respect to that controller are setup using the demand
mode. Using demand mode decreases the portion of the bus
bandwidth consumed by tape read/write transfers and improves
system performance during tape access.
F/f: Floating/Pulled-Up Drive Search
F When searching for drives on the system controller, use
a special ``floating track 0'' drive search. The
``floating'' drive search assumes the track 0 floppy
interface line floats (can be high or low) when no
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drive is attached. This algorithm works in all machines
but can't locate a drive which is executing a load-
point operation. The floating search is required on
certain Adaptec controllers.
f When searching for drives on the system controller, use
the standard ``pulled-up track 0'' drive search. The
standard algorithm assumes the floppy interface's track
0 line is pulled up (is high) when no tape drive is
attached. When the standard search is employed on a
controller which ``floats'' the track 0 line, a drive
may be erroneously detected at a line where none is
present. To deal with this condition either the IRDRV
configuration variable may be set to specify the drive
line (preferred) or the ``floating track 0'' drive
search (F) may be specified.
When neither (F) nor (f) is set, automatic configuration of
this option is performed by examining the model information
returned from the BIOS ``Get Machine Configuration'' service
(int 15, AH = C0). The following model uses the
``floating'' drive search (F):
Model Type Sub-type PS/2 Model
___________________________________
F8 0D 24 MHz Model 70
All other models use the ``pulled-up track 0'' search (f).
H/h: Do/Don't Test for 4100 PC Bus Controller Signature
H Test for Irwin 4100 PC Bus controller (default).
h No 4100 PC controller present.
In the PC or AT (not Micro Channel) hardware environment
(see the M/m option), when testing for the presence of a
4100 PC controller, the driver reads a byte from a signature
port on the controller and compares this against the value
45 hexadecimal. The I/O port address of the signature port
is found by adding six to the board's base port address (see
the controller configuration section). For a 4100 PC Bus
controller with switches set to ``as shipped from the
factory'' positions, the signature port address is 0370
(hexadecimal) + 6. If the byte compares the 4100 PC is
present. Otherwise it isn't. This option is intended to be
used when peeking at the factory set (0376 hexadecimal)
signature port causes the disruption of some other adapter
which is present at this address. Note that the driver can
be instructed to find the controller at a different address
by setting the 4100 parameter.
I/i: Do/Don't Wait-for-Index
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I Wait-for-index before data transfer of each tape block.
i No need to wait-for-index before data transfer.
When neither (I) nor (i) is set, wait-for-index is enabled
by default only when an Olivetti Micro Channel machine is
present, otherwise wait-for-index is disabled.
If the following symptoms are experienced, after installing
the MC driver in certain Micro Channel machines, the wait-
for-index algorithm may need to be enabled:
⊕ On the first backup this message is seen:
mc tape write error: Defect list has unrecoverable error
⊕ If tape format gives the error:
Formatting failed: Block 0 medium error :
phase: CERTIFICATION, track: 0, cylinder: 0
⊕ Extremely poor performance is experienced while listing the
content of or restoring a previously written tape.
A condition exists in some Micro Channel computers which
causes errors reading the first sector of each tape block.
Included are the IBM models 50, 60, and 80, and the Olivetti
P-500.
These machines employ 72065 (except for the Olivetti which
has a 765) floppy controllers and data separators with
certain characteristics. The 72065 differs from other
controllers in that it does not inhibit VCO SYNC when an
INDEX signal is received. Characteristically the data
separator circuit will: 1) have a phase lock loop (PLL)
which totally loses synchronization when confronted with a
50/50 duty cycle read data signal and 2) be slow to re-
synchronize while in the ``data following mode.'' Most
Irwin drives generate a read data signal with the 50/50 duty
cycle when transiting servo headers.
When these factors are combined, the following sequence of
events occurs during a tape read operation: A servo header
crosses the head. The drive sends a 50/50 duty cycle 250
KHz signal on the read data line. The PLL loses sync (that
is, the loop control voltage goes to a rail). The end of
the servo header crosses the head and the drive gives an
INDEX pulse. No corresponding VCO SYNC inhibit is generated
by the 72065 (this would normally put the PLL back on
track). Sector 1 crosses the head but the PLL is still too
far off to read the sector. The 72065 generates a record-
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MCCONFIG(F) XENIX System V MCCONFIG(F)
not-found error.
Some Irwin drives are fitted with a data compensator board.
This board has a circuit which alters the 50/50 duty cycle
to a value which allows most of these controllers to
maintain PLL synchronization. One exception is certain
Model 80s.
For Micro Channel systems which don't have the compensator
(and certain Model 80s which do), this problem can be
circumvented by software. The technique relies on a feature
of the 72065 (and other controllers in the 765 class): A
VCO SYNC inhibit is generated just after the last byte of a
READ command is sent to the controller. Inhibiting the VCO
SYNC pin (which is normally telling the PLL to lock on
incoming read data) causes the VCO's input to be switched to
a reference. This results in quickly returning the PLL to a
state in which it will be nearly synchronized with the
``real'' read data. VCO SYNC inhibition results from
programming the floppy controller using a ``wait-for-index''
algorithm.
The wait-for-index algorithm sends all but the last byte of
the data transfer command to the 72065. It then waits for a
logical high to low transition of the floppy INDEX signal.
The wait is accomplished by polling a special I/O port (at
address 03F0h) provided by the Micro Channel floppy
controller. The wait is used to delay the writing of the
last byte of the 72065 transfer command until after the
INDEX transition. As a result, the 72065 generates an
inhibit pulse on VCO SYNC after INDEX, but with sufficient
lead time to allow the PLL to achieve synchronization.
Thus, sector one's ID can be correctly read.
As no index interrupt is available, wait-for-index polls to
accomplish its task. The sought INDEX event is time
critical. A high priority daemon is awakened to poll for the
index transition. Using the wait-for-index algorithm has
the following drawback: All other system task time
processing is stopped until index polling is complete. This
means the user will see sluggish system performance at
certain times. Typically a 3 or 4 second dead period at
tape track switch time. This may prove unacceptable in
certain installations.
M/m: Micro-Channel-Architecture/PC-Bus
M This computer has a Micro Channel Architecture bus.
m This machine doesn't have a Micro Channel Architecture.
When neither (M) nor (m) is set, automatic configuration
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determines if Micro Channel Architecture hardware is
present. The M/m option is used for automatic configuration
of the B/b, I/i, and P/p options.
If the string ``EISA'' is found at physical memory location
0xfffd9, (BIOS ROM location F000:FFD9) this is not a Micro
Channel Architecture. Otherwise if all 8 bits of the I/O
port at address 0x0080 (DMA page register 0 in an AT
compatibles) can be modified this is an AT 286/386
compatible. Otherwise this is a Micro Channel Architecture.
O/o: System Controller Does/Doesn't Support 1-Meg Transfers
O The system controller supports one Megabit data
transfers.
o One Megabit transfers are not supported by the system
controller.
When neither (O) nor (o) is set, automatic configuration
determines whether the system controller supports 1-Megabit
transfer rates. This is important when a 2120 is attached
to the system controller. If the controller does not
support 1- Megabit transfers, 500-Kilobit transfers are used
for 80 and 120 Megabyte tapes. The driver detects the
presence of the following 1-Megabit controllers: Intel
82072 and 82077. 80 and 120 Megabyte drives do not work if
the driver thinks the hardware is capable of 1-Megabit
transfers and it is not. In the reverse situation, transfer
performance is degraded.
P/p: 4251 Is/Isn't Present
P A 4251 board is present in the system and has its
jumpers configured to address the 4251 digital output
register (DOR) at 0372h. When present the tape driver
echoes commands sent to the system floppy controller's
DOR (at I/O port address 03F2h) to the 4251 DOR. This
address can be configured using the 4251 parameter.
p No 4251 board present.
When neither (P) nor (p) is set, and when running in a PC-
bus (non-Micro Channel) machine (see the M/m option),
automatic configuration determines the presence of a 4251
board by reading I/O port 0372h and comparing the input byte
to the signature of the 4251. The 4251 signature byte is
42h. This address can be configured using the 4251
parameter.
Q/q: Compaq Portable III Piggy Back Tape Unit Is/Isn't
Present
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MCCONFIG(F) XENIX System V MCCONFIG(F)
Q A Compaq Portable III piggy back tape unit is present.
q No Compaq Portable III piggy back tape unit is present.
When neither (Q) nor (q) is set, the algorithm used to test
for presence of an alternate (Compaq Portable III piggy
back) controller does the following: First the model byte
is checked to see if the machine is other than an 8086 class
machine (that is, the model byte must be less than FE). If
this test passes, the BIOS address F000:FFEA is checked for
the string 'COMPAQ'. When a match is found, the I/O port at
0374 (that is, the alternate floppy controller chip status
port) is read and the three low order bits are tested. If
all three bits are zero, the alternate controller is
present.
When an alternate floppy controller is present, the
following port addresses are used by default:
765 765
Base DOR Stat Data Clock
_______________________________________________________________
03F0 03F2 03F4 03F5 03F7 Primary FLOPPY controller
0370 0372 0374 0375 0377 Alternate TAPE controller
See the Controller Parameter Configuration section for
information on reconfiguration of the default base address.
X/x: One Megabit Transfers Are/Aren't Allowed
X Allow 1 Megabit transfers when conditions permit.
x Never allow 1 Megabit transfers.
By default, 1 Megabit transfers (X) are allowed. If 1
Megabit transfers overload the system bus, the (x) option
should be configured.
IRDBG: Debugging Options
Several debugging flags are available:
s Drive search debug
When (s) is set, the result of the tape drive search
(presence test) is shown. The following shows an example:
4100MC:3=CTLRNOTFND :2=CTLRNOTFND :1=CTLRNOTFND :0=CTLRNOTFND
4100MCB:3=CTLRNOTFND :2=CTLRNOTFND :1=CTLRNOTFND :0=CTLRNOTFND
4100:3=DRVNOTFND :2=tapedrive :1=DRVNOTFND :0=DRVNOTFND
4100B:3=CTLRNOTFND :2=CTLRNOTFND :1=CTLRNOTFND :0=CTLRNOTFND
ALTFDC:3=CTLRNOTFND :2=CTLRNOTFND :1=CTLRNOTFND :0=CTLRNOTFND
SYDFDC:3=DRVNOTFND :2=tapedrive :1=nottested
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MCCONFIG(F) XENIX System V MCCONFIG(F)
The order of drive presence testing is shown left to right
and top to bottom. On a given line, the left most field has
a symbol which represents a controller. Numeric fields
preceded by a colon (:) give the unit select in the range 0
through 3. Fields preceded by an equal sign (=) have a
symbol which represents result of tape drive presence
testing for the controller and unit. These fields normally
have a upper case symbol which represents a driver error
code. Two special strings are used: ``tapedrive'' if a
drive was found, or ``nottested'' if drive presence was not
tested.
i Initialization value debug
When (i) is set, certain initialization values are
displayed. The following is an example:
hz=60 12_us_scaler=12 scaler_loops=27510 model=0x1FC
is64kdma=1 demanddma_ok=1
isuchannel=0 port_4251=3F0
timers=[ 0 1 2 1 2 7 19 37 181 235 ]
r Interrupt debug
When (r) is set, a character is displayed for each interrupt
processed by the driver's finite state machine. In
addition, reset cycles are shown. The following lists the
characters and their meanings:
Character Meaning
_____________________________________________________________________
N Floppy controller (NEC) interrupt
T Timer Interrupt
R Reset sent to floppy controller (start of reset)
r Reset complete
x Data transfer debug
When (x) is set the status of a transfer request is
displayed at interrupt time. The display is similar to that
shown below:
Cylinder
|
| DMA
| Overruns
| | Alternating
Track| | Positional Asterisk
| | | Retries |
| | | | |
| | | | Interrupt |
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MCCONFIG(F) XENIX System V MCCONFIG(F)
| | | | Status | Sector Map
+--+ +---+ +--+ +--+ +---------+ | +--------------------+
| | | | | | | | | | | | |
T= 2 C= 42 O=12 R= 0 CRC *[-c-- --Cs ---- M-O- --]
Track (T=decimal number) has the transfer request's track
number.
Cylinder (C=decimal number) has the transfer request's
cylinder number (tape block for the given track).
DMA Overruns (O=decimal number) has a count of DMA overruns
(excluding, if indicated by in the Interrupt Status, the
current DMAOVERRUN).
Positional Retry (R=decimal number) has the current
positional retry number for the request. Note that a
``free'' retry is allowed under the following conditions: 1)
A track switch was performed. 2) The tape is moving
logically forward, this transfer request's target head,
cylinder, and sector addresses match current values, but
there is some positional uncertainty because this transfer
request was not not started on the completion thread of the
previous request (That is, the period of time the tape has
been moving between requests is not known). 3) A DMA
overrun has occurred during the previous pass for a given
read/write/verify request.
Interrupt Status has the current reason for the interrupt
displayed symbolically.
Alternating Asterisk (*). This one character field is
alternately set with an asterisk (*) and a space (' ')
character so that screen updates may be distinguished.
Sector Map displays a visual indication of the status of
each sector when an error occurs. For example:
([-c-- --Cs ---- M-O- --])
Each printing character in the sector map represents the
status of a sector. Before the start of a transfer, each
entry is set to (s). On successful transfer of a sector,
the corresponding entry is set to a hyphen (-). The
following is a list of characters which appear in the sector
map and their meanings:
Character Interrupt Error
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Num Symbol Description
_________________________________________________________________________
- 0 IE_NOERR No error
C 12 IE_CRC Data CRC error
c 13 IE_IDCRC ID CRC error
s 14 IE_RECNOTFND Record not found
M 16 IE_DATAMARK No data address mark
O 17 IE_DMAOVERRUN DMA overrun
? other unexpected Unexpected value
IRDRV, IRSRCH: Drive Search Control
IRDRV drive searching sequence (old method)
IRSRCH drive searching sequence (new method)
The tape driver uses a default drive searching sequence to
test for the presence of tape drives. The default sequence
may be replaced with a user configured sequence using either
the IRDRV or IRSRCH variables. This is useful in situations
where tape drives are erroneously detected by the default
sequence, or where multiple tape drives are supported and a
different mapping of logical to physical drives is desired.
For example:
IRSRCH=SYSFDC:3,4100:2
This searches for a tape drive at unit select 3 on the
system floppy controller, and unit select 2 on an Irwin 4100
PC bus controller.
The equivalent IRDRV specification is:
IRDRV=04,43
or alternately:
IRDRV=4,43
IRDRV specifications use a 2-digit number to specify a
controller and unit select. The high-order digit gives the
controller, and the low-order the unit select. If the
high-order digit is missing, 0 (for the system floppy
controller) is assumed. Note that the unit select used by
IRDRV is in the range 1-4 while the unit select used by
IRSRCH is in the range 0-3.
The following is a list of controllers supported by IRSRCH
and IRDRV:
IRSRCH IRDRV
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Name High
Digit
___________________________________________
SYSFDC 0 System floppy
ALTFDC 1 Alternate floppy
4100MC 2 Irwin 4100 Micro Channel
4100MCB 3 Second 4100 Micro Channel
4100 4 Irwin 4100 PC Bus
4100B 5 Second 4100 PC Bus
The syntax of an IRSRCH drive search sequence specification
is:
IRSRCH=searchlist
searchlist = searchspec
searchspec,searchlist
searchspec = controller:unitlist
controller = SYSFDC (System floppy controller)
ALTFDC (Alternate controller)
4100MC (Irwin 4100 Micro Channel tape controller)
4100MCB (Second 4100 Micro Channel controller)
4100 (Irwin 4100 PC Bus tape controller)
4100B (Second 4100 PC Bus controller)
unitlist = unit
unit:unitlist
unit = 0
1
2
3
The syntax of an IRDRV drive search sequence specification
is:
IRDRV=searchlist
searchlist = searchspec
searchspec,searchlist
searchspec = controllerdigitunitdigit
controllerdigit = 0 (System floppy controller, may be omitted)
1 (Alternate controller)
2 (Irwin 4100 Micro Channel tape controller)
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MCCONFIG(F) XENIX System V MCCONFIG(F)
3 (Second 4100 Micro Channel controller)
4 (Irwin 4100 PC Bus tape controller)
5 (Second 4100 PC Bus controller)
unitdigit = 1
2
3
4
SYSFDC, ALTFDC, 4100, 4100B: Controller Parameter
Configuration
Certain variables may be set to specify tape controller
specific parameters. For example:
4100=P:370,I:6,D:2,T:2,T:0
says an Irwin 4100 PC bus controller is installed and
configured with a base I/O Port address (P) 0370
hexadecimal, using IRQ (I) 6, DMA channel (D) 2, and has two
tape units (T), one wired for physical unit select number 2,
and the other 0.
The general form for controller parameter specifications is:
controller=paramlist
paramlist = parameter
parameter,paramlist
parameter = name:value
controller = SYSFDC (System floppy controller)
ALTFDC (Alternate controller)
4100 (Irwin 4100 PC Bus controller)
4100B (Second 4100 PC Bus controller)
name = P (Base I/O Port address)
I (Interrupt Request line (IRQ))
D (DMA channel)
T (Tape unit number [0-3])
value = [0123456789abcefABCDEF]+ (Hexadecimal number)
4100 PC Configuration Switch Settings
The following tables contain the 4100 PC bus switch
settings. (4100 Micro Channel settings are modified with
the PS/2 reference (setup) diskette.
Base |
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MCCONFIG(F) XENIX System V MCCONFIG(F)
Address| SW1 SW2 SW3 SW4
_______|_______________________
300 | ON ON ON ON
310 | off ON ON ON
320 | ON off ON ON
330 | off off ON ON
340 | ON ON off ON
350 | off ON off ON
360 | ON off off ON
* 370 | off off off ON
380 | ON ON ON off
390 | off ON ON off
3a0 | ON off ON off
3b0 | off off ON off
3c0 | ON ON off off
3d0 | off ON off off
3e0 | ON off off off
3f0 | off off off off
DMA |
Channel| SW5 SW6 SW7 SW8
_______|_______________________
1 | ON off ON off
2* | off ON off ON
IRQ| SW9 SW10
___|____________
3 | ON off
6* | off ON
* factory setting
4251: Floppy Extender Address Configuration
The Irwin 4251 adapter board augments the system floppy
controller. It extends the total number of drives which may
be attached from 2 to 4, and allows for the attachment of an
external drive. The 4251 uses a single drive select I/O
port. By design, the 4251 I/O port partially mimics the
functionality of the system floppy controller's drive select
port. The system controller's drive select port is called
the Digital Output Register (DOR). When written with
certain values, both the system controller's DOR and the
4251 drive select port activate a drive select line at the
floppy interface. In the standard ``as shipped from the
factory'' configuration, the 4251 port is addressed at 03F2
hexadecimal. The same address is used by system floppy
controller's DOR. Thus, in the standard configuration, the
4251 monitors (that is, listens to and uses) bytes written
to the system's DOR to select a drive. The 4251 uses unit
selects 2 and 3. Unit selects are used by the software and
should not be confused with the DRIVE SELECT jumpers on the
tape drive which are almost always set to DRIVE SELECT 2.
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In certain hardware environments, the standard 4251
configuration either doesn't detect the presence of or fails
to write tapes in a tape drive.
When a 4251 is configured for the standard address and is
connected to:
⊕ a DTC controller, data is never written to tape. The
reason: DTC controllers disable the floppy interface
WRITE GATE signal when unit selects 2 or 3 (the third
and fourth) selects are activated. This means the tape
drive's write circuitry is never enabled.
⊕ an Adaptec suffix 'B' controller (e.g., ACB-2xxxB or
1542B SCSI controllers), driver software never detects
the presence of a tape drive. The reason: Adaptec
suffix 'B' controllers drive the TRACK 0 line active
for unit selects 2 or 3. The TRACK 0 line is the line
used by the drive to return the results of status
requests and motion commands issued by the driver
software.
The conditions listed in the above three paragraphs can be
overcome. Typically reconfiguring the 4251 to use the
recommended alternate address by installing the A7 jumper
allows the tape drive to function correctly. When this is
done, the 4251 I/O address moves from 3F2 to 372
hexadecimal.
When configuring the address of the Irwin 4251, the board
address jumpers are changed from the ``as shipped'' A0, A2,
A3 position. Normally the change involves reinstalling a
jumper stored on one pin of the A7 pin pair to connect the
``A7'' pin pair. This selects the address 372. However,
when a secondary floppy controller (such as the Irwin 4100)
or other adapter is present the 372 address may be in
conflict. In general, a secondary floppy controller uses
addresses in the range 370 through 377, which includes the
alternate ``372'' address of the 4251. To resolve this
conflict, the 4251 can be re-addressed. In addition, the
tape driver software must be informed of the new address.
The following information is given to aid in understanding
of the relationship of the 4251 and tape driver software,
the meaning of the 4251 jumpers A0 through A9, and an
example of a non-standard configuration.
At initialization, the tape driver software tests for the
presence of a 4251 at an alternate address. By default, the
alternate address is 372 hexadecimal. (To select the 372
address on the 4251 install jumpers across the A0, A2, A3,
and A7 pin pairs.) The test reads a byte from the alternate
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MCCONFIG(F) XENIX System V MCCONFIG(F)
address and compares the byte with the signature. When the
4251 select port is read, a signature byte (42 hexadecimal)
is returned. If the signature compares, the driver sends
select bytes to both the system's DOR and the 4251 port.
The default alternate address may overridden by using the
variable named ``4251.'' For example,
4251=31f
tells the driver to test and use, if present, the port at
31F hexadecimal.
The 4251 port uses a single 10-bit I/O port address. The
address is set using the jumper pin pairs labeled A0 through
A9. Each jumper pin pair corresponds directly with an I/O
port address bit. When a jumper pin pair is connected, the
corresponding address bit is set to a logical 0. When the
pin pair is disconnected, the address bit is set to a
logical 1.
For example, to address the 4251 at 31F (an address which is
unlikely to conflict with standard adapters), connect jumper
pin pairs A5, A6, and A7.
Files
/etc/default/mcconfig
/etc/mcdaemon
See Also
tape(C), tape(HW)
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