Number: 912

Date:  1-May-84 18':39':43

Submitter: Sannella.PA


Subject: Document format of Alto .DM files (as produced by DUMPLOAD)

Assigned To: 

Attn: documentation

Status: Open


Problem Type: Documentation

Impact: Minor

Difficulty: Moderate

Frequency: Everytime

Priority: Unlikely

System: Other Software

Subsystem: Other



Lisp Version: 

Source Files: 

Microcode Version: 

Memory Size: 

File Server: 

Server Software Version: 


Description: '
Date': 15 Apr 84 16':30 PST'
Subject': [Ron Newman <>': Re': The Structure of .DM files]'
To': LispSupport'
cc': vanMelle'
should be included in documentation of DUMPLOAD, suitably edited'
Subject': Re': The Structure of .DM files'
Dump file format is described in section 5 (the last two pages) of [indigo]<AltoDocs>Executive.TTY.   For your convenience':'
5. Dump Format'
A dump file is a sequence of blocks of eight-bit bytes. The  first byte'
of each block is the block type. A typical dump file might look like':'
        <name block><date block><data block 1>...<data block n>'
      <name block><date block><data block 1>...<data block m>'
      <end block>'
Name Block - Type=#377'
A name block  contains two bytes of  file attributes and then  the file name. (Ignored by load, set to 0 by Dump).'
Data Block - Type=#376'
A data block contains two bytes of byte count (high-order  byte first), two bytes of checksum (high-order  byte first), and a sequence  of data bytes.  The  byte  count  must  be  less  than  or  equal  to  256  for compatibility with Novas, and  the count does not include  the checksum or byte  count; only the  data bytes are  counted.  The checksum  is a 16-bit  add ignoring carry,  over the data and byte count. If the block has an odd number of bytes,  the last byte is NOT included in the checksum computation.'
End Block - Type=#374'
An end block has no contents and terminates a Load.~.'
Date Block - Type=#373'
Date blocks  with six bytes  of date are  generated; contains the four byte Alto creation date into the first  four bytes and  zeros  the  remaining  two.  Date blocks are optional.


Test Case: 

Edit-By: Masinter

Edit-Date: 13-Jul-84 16':55':36