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+mINT13.SYS is an MS-DOS device driver which implements a memory cache
+for data referenced on IBM-PC XT/AT Hard disks. It caches at the
+"INT 13H" level and caches tracks.
+
+NOTE WARNING: There is a "re-boot" bug in RAMDrive version 1.16. When
+                INT13 and RAMDrive are both installed, it is possible
+                that Ctrl-Alt-Del will not work. This problem is "fixed"
+                by updating your RAMDrive to version 1.17 or later.
+
+IN CONFIG.SYS:
+
+    device = [d:][path]int13.sys [bbbb] [/e | /a] [/d] [/wt:on] [/wc:off]
+                                 [/t:nnnnn] [/r:on] [/c:on]
+
+        bbbb  First numeric argument, if present, is cache size
+                in K bytes. Default value is 256. Min is 128. Max
+                is 4096 (4 Meg).
+
+        /e    Specifies that PC AT Extended Memory is to be used.
+                It is an error if /E is specified on a machine other
+                than an IBM PC AT. /E is the default.
+
+              NOTE: There is 1k of INT13 overhead. That is to say,
+                if there are 512k bytes of extended memory, there
+                will be 511k bytes available for assignment to INT13.
+
+        /a    Specifies that Above Board memory is to be used. It
+                is an error if the above board device driver is not
+                present.
+
+        Neither /A or /E Specifies /E
+
+        NOTE: THESE ARE THE ONLY CONFIGURATIONS. You must either have an
+                Above Board (or compatible), or you must have extended memory
+                on an IBM PC-AT (or compatible).
+
+        /d    Disable caching. Causes INT13 to come up with caching
+                disabled (default is enabled).
+
+        /wt:on Enable write through. When INT13 is
+                caching write information, it is a good idea to imply
+                a flush of the cache on some operations so that in
+                case of a crash or power failure the information in
+                the cache which is not on the disk will not be lost.
+                /wt:on enables write through on full track INT 13s which
+                are to tracks not currently in the cache. /wt:off
+                disables it. INT13 is faster with write through
+                disabled, at the expense of there being a bigger risk of
+                loosing data. /wt:on IS NOT a substitute for flushing
+                before a re-boot!!!! The write through mechanism is far
+                from perfect, all it is is a risk REDUCER, not a risk
+                eliminator. Write through is off by default.
+
+        /wc:off - Disable write caching. There is risk when
+                caching "dirty" information that the system will crash,
+                or be re-booted, or be turned off before this
+                information can be written to the disk. This may
+                corrupt the disk. This risk can be ELIMINATED, at the
+                expense of cache performance, by NOT caching any dirty
+                information. /wc:off disables the caching of dirty
+                information, eliminating the risk. Write caching is
+                on by default.
+
+        /t:nnnnn - Set the auto flush interval. INT13 listens on the
+                system timer to note the passage of time and "age" the
+                dirty information in the cache. Every nnnnn ticks,
+                the cache is flushed. The timer ticks 18.2 times a
+                second.
+
+                 nnnnn   |
+                ===========================================
+                    18   |     Flush every second
+                  1092   |     Flush every minute
+                  5460   |     Flush every 5 minutes
+                 10920   |     Flush every 10 minutes
+                 21840   |     Flush every 20 minutes
+                 32760   |     Flush every 30 minutes
+                 65520   |     Flush every hour
+
+                The default setting of nnnnn is 1092 or every minute.
+                nnnnn = 0 causes a wait for 65536 ticks which is a
+                little over an hour. The max value for nnnnn is 65535.
+
+        /r:on - Enable re-boot flush.
+                This enables the flush on re-boot logic. The default
+                is /r:off. This enables a flush in the Ctrl-Alt-Del
+                keyboard re-boot logic. NOTE WARNING DANGER!!!!!!!!
+                Enabling this feature can cause strange system behavior.
+                You will have to type Ctrl-Alt-Del twice at least. This
+                can adversly effect other software in the system.
+                The result of this can be very unpredictable.
+
+        /c:on - Enable all cache on reads.
+                Normally INT13 does not cache EVERY I/O. Whenever
+                it sees a full track I/O which is not currently in
+                the cache, it DOES NOT cache that track. This is
+                an optimization for "typical" operation, and actually
+                increases performance. This is the default setting
+                (/c:off). There may be some cases where it is desirable
+                that ALL reads be cached. One example is that you are
+                "loading" the cache prior to locking it with FLUSH13 /l.
+                With /c:off, some pieces of what you're trying to load
+                may not get into the cache. Another example is that
+                you continually access in a sequential manner (like
+                program load) some large file which happens to be
+                contiguous on the disk. Again, there may be some "piece"
+                of the file which does not get into the cache with
+                /c:off. /c:on enables the caching of ALL reads.
+                NOTE: The same "don't bother caching operations which
+                      are full track and not in the cache" applies
+                      to writes as well. /c has NO EFFECT on this
+                      behavior however. /c only effects read operations.
+
+
+
+MESSAGES:
+
+
+     INT13: Above Board Memory Manager not present
+
+The /A switch was given but INT13 could not detect the presence of the
+Above Board memory manager. You need to have a
+
+        device = EMM.SYS
+
+line in your CONFIG.SYS file before you have any device = int13.sys
+lines. INT13 will install a driver, but it will be non-functional.
+
+
+     INT13: Above Board Memory Status shows error
+
+During the process of trying to set up the cache in Above Board memory
+an error was detected. Run the Above Board Confidence test to test
+your Above Board memory. INT13 will install a driver, but it will be
+non-functional.
+
+
+     INT13: Computer must be PC-AT, or PC-AT compatible
+
+The /E switch can only be given on an IBM PC AT or an IBM PC AT
+compatible computer that has the FCH model byte (byte at FFFF:000E).
+INT13 will install a driver, but it will be non-functional.
+
+
+     INT13: No extended memory available
+
+Your system has NO memory for RAMDrive drives.
+INT13 will install a driver, but it will be non-functional.
+
+
+     INT13: Insufficient memory
+
+Your system has some memory available for INT13 cache, but not enough
+to set up a driver. INT13 will install a driver, but it will be non-functional.
+
+
+     INT13: Invalid parameter
+
+You specified too many parameters, your numeric parameter is not
+valid, you specified conflicting or too many switches. Edit your CONFIG.SYS
+file and fix the INT13 line. INT13 will install a driver, but it will
+be non-functional.
+
+
+     INT13: Incorrect DOS version
+
+INT13 only runs on 2.X and 3.X versions of DOS.
+INT13 will install a driver, but it will be non-functional.
+
+
+     INT13: I/O error accessing cache memory
+
+During the set up of the INT13 cache, an error was detected trying to
+access the cache memory. Run any memory tests you have that will
+exercise your extended or expanded memory.
+INT13 will install a driver, but it will be non-functional.
+
+
+     INT13: No hardfiles on system
+
+INT13 could not find any hardfiles on your system. Only hardfiles
+which are compatible with IBM hardfiles at the ROM BIOS INT 13H
+level can be supported. INT13 will install a driver, but it will
+be non-functional.
+
+
+     INT13: Too many bytes per track on hardfile
+
+One of the hardfiles on your system defined a very large track.
+This track is too large for INT13 to be able to cache it.
+INT13 will install a driver, but it will be non-functional.
+
+
+     Microsoft INT13 Cache version Y.YY
+
+INT13 Header message, Y.YY is the version of INT13.
+
+
+    Cache size: nnnnk in UUUUUU Memory
+    Room for tttt tracks of ssss sectors each
+
+This is an informational message from INT13 telling you how many Kilo Bytes
+of memory were assigned to the cache and what type of memory it is, how many
+tracks this allows to be buffered and how many sectors there are per track.
+
+NOTE: There is nothing to "prevent" you from having two device = INT13.SYS
+      lines in your CONFIG.SYS file, but you should not do this. Very
+      unpredictable behavior will occur, and FLUSH13 will only "talk" to
+      one of them.
+
+INT13 has several behavior aspects that can be changed. This is done
+with the FLUSH13 utility.
+
+  FLUSH13 [/s|/sx|/sr] [/d|/e] [/l|/u] [/i] [/f] [/wt:on|/wt:off]
+          [/wc:on|/wc:off] [/t:nnnnn] [/r:on|/r:off] [/c:on|/c:off]
+
+        No arguments - This causes FLUSH13 to flush out any "dirty"
+                tracks in the INT13 cache. A "dirty" track is one
+                which has been written into the cache, but not yet
+                written to the disk. This invokation causes all dirty tracks
+                to be written out to the disk so that the system can
+                be re-booted or turned off. NOTE: FAILURE TO FLUSH
+                THE CACHE BEFORE A RE-BOOT OR POWER OFF CAN CAUSE THE
+                INFORMATION ON THE HARDFILE TO BE CORRUPTED.
+
+        /f      - Flush. Same as the no arguments case, but allows you to
+                perform the flush and do something else (like /s).
+
+        /i      - Flush and invalidate. This is the same as the no argument
+                case except that all of the information in the cache
+                is also discarded. This makes the cache EMPTY.
+
+        /d      - Disable caching. This causes all dirty cache information
+                to be flushed and all caching to stop.
+
+        /e      - Enable caching. This causes caching to be enabled after
+                a previous /d disable. When INT13 is started it is enabled.
+
+        /l      - Lock the cache. This causes all dirty information to be
+                flushed, and the cache contents to be locked in the cache.
+                When in this mode the locked elements will not be discarded
+                to make room for new tracks. This can be used
+                to "load" the cache with desired things. For instance if
+                you use the "foobar" program a lot, you can run foobar,
+                causing it to be loaded into the cache, then lock the cache.
+                This causes the foobar program to always be in the cache.
+                You may lock the cache as many times as you want. Each lock
+                causes the current information (including any previously
+                locked information) to be locked.
+                NOTE: Information in a locked cache is READ ONLY!! Any write
+                operation on information in a locked cache causes the
+                information to be unlocked.
+
+        /u      - Unlock the cache. This undoes a previous /l and returns
+                the cache to normal operation.
+
+        /s      - Print status. This displays the settings of the setable
+                device parameters.
+        /sx     - Print extended status. Same as /s, only additional
+                Statistical information is also given.
+        /sr     - Reset statistics. Same as /sx, only the additional
+                Statistical information is reset to 0.
+
+        /wt:on off - Enable or Disable write through. When INT13 is caching
+                write information, it is a good idea to imply a flush of
+                the cache on some operations so that in case of a crash or
+                power failure the information in the cache which is not on
+                the disk will not be lost. /wt:on enables write through on full
+                track INT 13s which are to tracks not currently in the cache.
+                /wt:off disables it. INT13 is faster with write through
+                off, at the expense of there being a bigger risk of
+                loosing data. /wt:on IS NOT a substitute for flushing before
+                a re-boot!!!! This write through mechanism is far from perfect,
+                all it is is a risk REDUCER, not a risk eliminator. /wt:off
+                is the setting when INT13 is started.
+
+        /wc:on off - Enable or Disable write caching. There is risk when
+                caching "dirty" information that the system will crash,
+                or be re-booted, or be turned off before this information
+                can be written to the disk. This may corrupt the disk.
+                This risk can be ELIMINATED, at the expense of cache
+                performance, by NOT caching any dirty information.
+                /wc:off disables the caching of dirty information,
+                eliminating the risk. /wc:on enables the caching of dirty
+                information. /wc:on is the default when INT13 is started.
+
+                WARNING: You must be careful to flush the cache before
+                  re-booting the system, or turning it off if /wc:on is selected.
+                  You should also be careful to disable the cache (/d), or do
+                  /wc:off before running any program under development which
+                  has a chance of crashing due to bugs.
+
+                NOTE: When /wc:off is selected, write info CAN get into
+                  the cache (when the write is to a track which is currently
+                  in the cache). The difference is that this "dirty" information
+                  is IMMEDIATELY written out to the disk instead of being
+                  held in the cache in the "dirty" state. When the write is
+                  to a track that is not in the cache, it will be passed
+                  through to the disk without being cached.
+
+        /t:nnnnn - Set the auto flush interval. INT13 listens on the system
+                timer to note the passage of time and "age" the dirty
+                information in the cache. Every nnnnn ticks, the cache is
+                flushed. The timer ticks 18.2 times a second.
+
+                 nnnnn   |
+                ===========================================
+                    18   |     Flush every second
+                  1092   |     Flush every minute
+                  5460   |     Flush every 5 minutes
+                 10920   |     Flush every 10 minutes
+                 21840   |     Flush every 20 minutes
+                 32760   |     Flush every 30 minutes
+                 65520   |     Flush every hour
+
+                The default setting of nnnnn is 1092 or every minute.
+                NOTE: There is no way to "disable" this tick aging. Setting
+                      nnnnn = 0 causes a wait for 65536 ticks which is a
+                      little over an hour. The max value for nnnnn is 65535.
+                      Disabling the cache (/d), or turning write caching
+                      off (/wc:off) effectively prevents the aging from
+                      doing anything as there is never anything to flush
+                      in these cases. Setting very low values of nnnnn
+                      should be avoided as it places a lot of overhead into
+                      the timer interrupt service. Rather than set low values,
+                      it is better to just turn off write caching (/wc:off).
+                NOTE: As stated above, the max value for nnnnn is 65535. It
+                      should be noted however that FLUSH13 DOES NOT object if
+                      you specify a number larger than this! It will simply
+                      use only the low 16 bits of the number.
+
+        /r:on off - En/Disable reboot flush.
+                INT13 has a provision for detecting Ctrl-Alt-Del user
+                reboots. /r:on enables a flush of the cache at this time
+                to prevent the disks from being corrupted. The default
+                setting is /r:off. NOTE WARNING DANGER!!!!! Enabling
+                this feature can prevent disks from being damaged BUT
+                the mechanism has flaws. For one, you will have to hit
+                Ctrl-Alt-Del a second time to get the system to reboot.
+                YOU MUST NOT POUND ON THE KEY. You will crash the system if
+                you do. Hit the key ONCE, if the system re-boots, fine. If
+                there is info to flush out of the cache, the drive light
+                will come on and the system will probably NOT reboot. WAIT
+                until the drive light is OFF before hitting Ctrl-Alt-Del
+                again. This feature of INT13 MAY NOT WORK with other
+                software in the system. USER BEWARE!!!!!!!!!!!!!!!!!!!
+
+        /c:on off - En/Disable all cache on reads.
+                Normally INT13 does not cache EVERY I/O. Whenever
+                it sees a full track I/O which is not currently in
+                the cache, it DOES NOT cache that track. This is
+                an optimization for "typical" operation, and actually
+                increases performance. This is the default setting
+                (/c:off). There may be some cases where it is desirable
+                that ALL reads be cached. One example is that you are
+                "loading" the cache prior to locking it with FLUSH13 /l.
+                With /c:off, some pieces of what you're trying to load
+                may not get into the cache. Another example is that
+                you continually access in a sequential manner (like
+                program load) some large file which happens to be
+                contiguous on the disk. Again, there may be some "piece"
+                of the file which does not get into the cache with
+                /c:off. /c:on enables the caching of ALL reads.
+                NOTE: The same "don't bother caching operations which
+                      are full track and not in the cache" applies
+                      to writes as well. /c has NO EFFECT on this
+                      behavior however. /c only effects read operations.
+
+If invalid or conflicting arguments are given, FLUSH13 prints a usage line.