ITS PDUMP format - Revision history

Jnc: +cat, links

2022-04-05T21:15:58Z

+cat, links

Larsbrinkhoff at 13:01, 5 April 2022

2022-04-05T13:01:11Z

Larsbrinkhoff: Document ITS PDUMP format.

2022-04-05T13:00:20Z

Document ITS PDUMP format.

New page

The '''ITS PDUMP''', or pure dump, format was made to allow ITS programs to share read-only pages.

====CREATING A PDUMP FILE====

The HACTRN :PDUMP command writes a core image file in PDUMP format.

====OVERVIEW====

A PDUMP file consists of three sections:
# Page map.
# Data pages.
# Symbol table.

All pages are 1024 (decimal) words.

====PAGE MAP====

The page map is the first page of the file. The first word is 0 to differentiate it from [[ITS SBLK format|SBLK]] files.

After this follow 256 (decimal) page map words.

{| class="wikitable
|-
| 0-27
| 27-35
|-
| Access
| Absolute or shared page number
|}

Access bits:

{| class="wikitable
| Bit
| Meaning
|-
| 0
| Absolute (system page)
|-
| 1
| Do not share file page; make a copy to virtual memory
|-
| 2
| Shared
|-
| 18
| Writeable
|-
| 19
| Readable
|}

The accumulators are stored in locations 1000-10017 (octal) in the first page.

====DATA PAGES====

After the page map comes data pages mapped into the address space, in the same order they appear in the map. Absolute and shared pages have no data page. Writable or readable pages do.

====SYMBOL TABLE====

Just like the SBLK format, after the core image data comes a start instruction, then a symbol table, and last a repeated start instruction.

← Older revision		Revision as of 13:01, 5 April 2022
Line 1:		Line 1:
−	The '''ITS PDUMP''', or pure dump, format was made to allow ITS programs to share ~~read-only~~ pages.	+	The '''ITS PDUMP''', or pure dump, format was made to allow ITS programs to share virtual memory pages between files, other jobs, and the system.

	====CREATING A PDUMP FILE====		====CREATING A PDUMP FILE====

@@ Line 1: / Line 1: @@
-The '''ITS PDUMP''', or pure dump, format was made to allow ITS programs to share virtual memory pages between files, other jobs, and the system.
+The '''ITS PDUMP''', or pure dump, format was made to allow [[Incompatible Timesharing System|ITS]] programs to share [[virtual memory]] pages between [[file]]s, other jobs, and the system.
 ====CREATING A PDUMP FILE====
@@ Line 10: / Line 10: @@
 # Page map.
 # Data pages.
-# Symbol table.
+# [[Symbol table]].
 All pages are 1024 (decimal) words.
@@ Line 55: / Line 55: @@
 ====DATA PAGES====
-After the page map comes data pages mapped into the address space, in the same order they appear in the map.  Absolute and shared pages have no data page.  Writable or readable pages do.
+After the page map comes data pages mapped into the [[address space]], in the same order they appear in the map.  Absolute and shared pages have no data page.  Writable or readable pages do.
 ====SYMBOL TABLE====
 Just like the SBLK format, after the core image data comes a start instruction, then a symbol table, and last a repeated start instruction.