LaserWriter IINTX SCSI Hard Disks: General Information


Configuring the hardware:

The extended ROM support of a disk-based file system and the 53C80 SCSI
controller with a 50-pin external connector allows you to attach one or more
SCSI hard disks to the LaserWriter IINTX. The addition of a hard disk acts as
"virtual memory", increasing the space available for font storage, font
caching, or a display list buffer.

When connecting hard disks to the LaserWriter II?ᠬ follow the standard SCSI
procedures:

- each disk drive must have a unique SCSI ID number

- no more than two SCSI cable terminators in a chain

- no more than 7 devices.

The LaserWriter IINTX controller does NOT provide termination of the SCSI
signals or active power for external terminators.

LaserWriter IINTX will NOT recognize any of the attached disks unless they are
ALL turned on when you want to use any one of them.

(NOTE: some manufacturer's disk drives do not have the intelligence to report
their size. These disk drives SHOULD NOT be used on the LaserWriter IINTX.)


Initialization:


Initialize the disks and download fonts to them with the LaserWriter Font
Utility application on the LaserWriter II installation disk.

Initialization allots 20 percent of total disk space to font storage, and 80
percent to font-caching. The LaserWriter IINTX automatically increases the
storage percentage as needed. The Font Utility application warns you when the
percentage is high enough to threaten font-caching performance.

The LaserWriter IINTX regards all attached hard disks as a single logical unit.
Therefore, if you add a disk to the system you will have to re-intialize ALL
your disks and rebuild your font storage. The font cache rebuilds itself
automatically. Because you can chain several hard disks, the space available
for font-caching is essentially unlimited, and thus the bit-maps are always
available.


Downloading:

When you download a font (and you have a hard disk attached,) you can choose to
download it either to the disk or to RAM. Downloading fonts to the disk stores
them there permanently (until you remove them). This process saves time,

because you won't have to download repeatedly over the AppleTalk network.


Start-up Sequence:

Postscript checks the disk device for file-system integrity -- and the
disk-based font cache for internal consistency -- each time the LaserWriter
IINTX is turned on. If the check for file-system integrity fails, the disk
device is re-initialized; for this reason you should ensure that ALL data on
the device is recoverable from another source.

If the check of the internal consistency of the disk-based font cache fails,
the information in the font cache is discarded, and associated data structures
and files are restored to their initial state. If these start-up diagnostics
are completed successfully, PostScript searches the disk device for a file
named Sys/Start.


Sys/Start File:

A Sys/Start file can be used to set volatile parameters and to load special
items into virtual memory before any other job is executed. If a Sys/Start file
is stored on the disk device, it will be executed if "dosysstart" is true,

right after completion of the start-up diagnostics.

If the file has become corrupt, it is necessary to restart the printer with the
disk device turned off. To prevent the file from being run, you need to set
"dosysstart" to FALSE -- then the Sys/Start file would not be executed the next
time the printer is turned on. (To replace the bad Sys/Start file, restart the
printer with the disk device turned on.)


Storing/Replacing the Start-up File:

The procedure used to download your Sys/Start file to the printer's disk
device is broken into two PostScript programs to preserve virtual memory, which
is consumed when working outside the server loop:

(NOTE: Virtual memory is not recovered until the printer is powered-down and on
again. To protect the system files, it is necessary to work outside the server
loop when accessing these Sys files.)

- The first job stores the text of your Sys/Start file to a temporary file. It
is not necessary to exit the server loop to perform this function.

- The second job exits the server loop, deletes the Sys/Start file if one

already exists, and renames the temporary file to Sys/Start.

Actual code is provided in the current Apple LaserWriter Reference manual.


Article Change History
15 September 1993 - Changed the LaserWriter model designators to upper case.
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Published Date: Feb 18, 2012