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Logical
Unit ACTIVATION:
If you installed a
new drive and either used the LU default
settings or made changes to the size of
LUs, you must now 'Activate' each
LU (Yes, if you created 10 user LUs, you
need to Activate each of the 10 LUs)!
During CONFIG, all that happened was the
Cylinder (Sector) allocation was divided
up into a number of LUs. Just like partitioning
a hard drive on a PC, you need to create an
INDEX and bitmap (BAM) for each LU. The way this
is done on the Lt. Kernal is to run the ACTIVATE
command.
When you run the
Activate command on a Configured new hard
drive, you'll do so from LU 10. After
you've installed SYSGEN and CONFIGured some user
LUs, you do a complete reset and powered up
the Commodore again. At this point, the only
LU that was automatically Configured and
Activated was the DOS LU - LU 10. Therefore,
when you run the Activate command, you'll do
so for each LU you created in the Configure step.
So, enter
'activate' and press Enter (Like all DOS
commands, the name is simply entered, in lowercase,
on the far-left column and then press Enter.)
The
first thing the Activate command wants to
know is which LU number do you want to create
(e.g. LU 0). You'll then be told that 'activating'
the LU will erase all data on the logical unit
and ask for a Y/N
response to continue. If you enter Y, you
should notice two things:
- On a new
screen, a number of star symbols (*)
start printing from left to right on
the top line of the screen. Not well
known or understood, the number of
stars represents the SIZE of the LU.
That is, if you are 'activating' a default
LU 0 on a small capacity drive, you may see
5 to 10 stars. However, if you have set the
LU to its' Maximum capacity (number of
Cylinders which represents 65,000
Blocks), the entire 40-column top line
and part of the second line may fill
with stars! This is particularly important
when visually verifying that LK DOS and the
HARD DRIVE understand the Size of the LU.
- After the star symbols finish
printing, the period (.) symbol will continue
printing 1 or 6 Rows of characters which
represents that it is erasing the LU.
When Activation is
complete, you are asked if you want to
install an 'image' of DOS (from LU 10)
onto the LU number you just Activated. The purpose
of this DOS 'image' (or copy of all DOS) was
meant to speedup DOS execution. Well, when
using the Mother of all Slow drives (Miniscribe
8425S), putting a copy of DOS on other LUs
did speedup execution times because the
commands are fetched from LU 10. That is,
the further the physical distance from LU
10 and the LU from which you requested the
command, the longer it takes to fetch the
DOS (seek times). However, if you are
using any 'reasonably fast' drive, installing
the DOS image on any LU will not noticeably
speedup file loading times. However, if you configure
two or more hard drives, the SCSI ID# 1 (or higher)
drive will have to go to the SCSI ID#0 drive for
DOS. And, if you use three hard drives and
the first drive (SCSI ID#0) is the slowest
drive, installing DOS images on the other
two drives is an excellent way to make use
of the slow drive! (It's the best way to make use
of the original/stock 20 meg Miniscribe
without slowing down the other two
drives!)
Furthermore,
running the 'updatedos' command will
automatically refresh All DOS images (should they
become corrupted) if they were previously install
on an LU (even on another hard drive). So, why
not? DOS images don't take up that much space
and DOS loading times May be improved. When I
build a new system and use multiple
drives, I always install a DOS image on
All LUs (normally all 10 User LUs).
Once the LU has
been Activated, it's ready for use and
files may be stored on and retrieved from
that LU only. Therefore, you need to Activate
All of your defined LUs. When you exit Activation,
you are returned to a blinking cursor with
no status line. To view the LU you have just
activated, enter that LU number on the far-left
column (e.g., LU 0) and hit Enter. For
a C64, you should now see the following
(unless you changed the default Drive# and
USER# in CONFIG):
C64
D#08 LU00 USER00
PORT#00
Now enter the
command 'DIR' and you'll see all of
the files currently on LU 00. On a
new drive, you should see the DISCBITMAP, SYSTEMINDEX
and DOS image file (if you installed it).
You will also see how many Blocks are still
available and how many Blocks are used, including
how much the Discbitmap and DOS individually
use.
The 'Blocks
available' represents the actual space you
have for storage. However, a HARD DRIVE Block
is 512 Bytes in size compared to a Commodore
Block size of 256 Bytes. Therefore, if you
store a Commodore file which is, say, 100 blocks,
you will see that the same file on the Lt. Kernal
only uses 50 Hard Drive Blocks. Keep this
block-size difference in mind before you
assume that the file is corrupt or bad!
This also means that if you set the LU
size to '65K' Blocks, you actually have
130,000 Commodore Blocks of storage on just
that one LU (e.g., 33 Meg).
USER
subdirectories:
Within each LU,
you can divide your file storage into
different USER areas (up to 16). This
does not require editing of your CONFIG file.
To use an USER area, first select its Number.
At the prompt line, enter USER 14, hit
Enter, and you'll now be in the USER
14 area. If you type in the DIR
command, the only files you'll see are the
ones that were placed in that LU &
USER number. Unlike UNIX or MS-DOS, there's no
file system hierarchy in the Lt. Kernal; merely
an user area scheme that corresponds to CP/M
storage. In fact, the user area number is pre-pended
to the disk directory entry and routines that
search the directory use the current user
area as part of the search pattern (even
if no pattern is specified, the user
area is implied. Furthermore, if you wanted
to open a file in BASIC, you could say
OPEN(2,8,2)"0:3:filename",
which would open a file that was on LU 0, USER
3.
Taking advantage
of the USER function is a great way of saving copies
or backup files. For example, you could setup
an LU 04 during CONFIG
just for backups. Within LU 04, you could then
place LU 00 backup files
in LU 04, USER 00; LU
01 backup files in LU
04, USER 01, and so on. There is no limit
on how (or if) the USER capability is
utilized.
Note: Keep in mind that you can only
store 4,000 files per LU (i.e., not
4K files in each USER # per LU#). Again, the
reason for this is because the USER function
is merely a directory entry scheme, which
adds the USER number to the file
name.
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