Difference between revisions of "SITS PDUMP format"
(Description of ths SITS pure dump format.) |
(Some clarifications.) |
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| − | The [[SITS]] | + | The '''Pure Dump''' format of [[SITS]] is a [[main memory|core]] image file format amenable to [[virtual memory|paging]]. Most of the file is divided into 8Kbyte [[virtual memory|pages]], suitable for [[PDP-11 Memory Management]]. |
| − | The overall structure is: one page with the page table and other metadata, pages with contents for the address | + | The overall structure is: one page with the page table and other [[metadata]], pages with contents for the [[address space]]s, and a [[symbol table]]. |
===Page table=== | ===Page table=== | ||
| − | The first page in the file starts with a zero word. | + | The first page in the file starts with a zero word. This is what distinguishes it from an [[PDP-11 Absolute Loader|absolute loader]] file. |
Next comes the page table: 16 words for the instruction space, and 16 for the data space. | Next comes the page table: 16 words for the instruction space, and 16 for the data space. | ||
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{{16bit-bitout}} | {{16bit-bitout}} | ||
| − | After the page table comes four words: the starting address, the size of the symbol table in bytes, and the file position of the symbol table as a long word. | + | After the page table comes four words: the starting [[address]], the size of the symbol table in bytes, and the file position of the symbol table as a long word. |
The rest of the page is empty. | The rest of the page is empty. | ||
| Line 20: | Line 20: | ||
===Content pages=== | ===Content pages=== | ||
| − | Only pages that are mapped and not absolute have content pages in the file. If a page is both in I and D spaces, the file only has the I copy. | + | Only pages that are mapped and not [[absolute address|absolute]] have content pages in the file. If a page is both in [[PDP-11 Memory Management|I and D spaces]], the file only has the I copy. |
| − | Pages that are shorter than 8K are padded out to a | + | Pages that are shorter than 8K are padded out to a 8K boundary. |
===Symbol table=== | ===Symbol table=== | ||
| − | After the last content page comes the symbol table. It does not have to end on a page | + | After the last content page comes the symbol table. It does not have to end on a page boundary. |
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| + | [[Category: PDP-11 File Formats]] | ||
Latest revision as of 12:06, 13 October 2022
The Pure Dump format of SITS is a core image file format amenable to paging. Most of the file is divided into 8Kbyte pages, suitable for PDP-11 Memory Management.
The overall structure is: one page with the page table and other metadata, pages with contents for the address spaces, and a symbol table.
Page table
The first page in the file starts with a zero word. This is what distinguishes it from an absolute loader file.
Next comes the page table: 16 words for the instruction space, and 16 for the data space.
The words have this format:
| D=I | Absolute | File | Private | Execute | Write | Read | Page Length | ||||||||
| 15 | 14 | 13 | 12 | 11 | 10 | 09 | 08 | 07 | 06 | 05 | 04 | 03 | 02 | 01 | 00 |
After the page table comes four words: the starting address, the size of the symbol table in bytes, and the file position of the symbol table as a long word.
The rest of the page is empty.
Content pages
Only pages that are mapped and not absolute have content pages in the file. If a page is both in I and D spaces, the file only has the I copy.
Pages that are shorter than 8K are padded out to a 8K boundary.
Symbol table
After the last content page comes the symbol table. It does not have to end on a page boundary.
