printout type blocks (not discussed in this article), values are parsed in a slightly different manner.plato:cdc.io:patch.structure
Table of Contents
Patch Structure
Overview
First, a warning:
Never Directly Apply
The format of the patch file MUST be precise and failure to understand how the format works can render a target useless/corrupt. For this reason, never apply a patch directly to a working file. Always apply to a disposable copy.
Moreover, patches from one system to another may require careful edits after patching is applied due to conditionals which may refer to system names, types, identifiers, or other location specific variables and artifacts.
The B66 file structure is a rough analog to that required by the PF command, but that's where the similarities end.
Each record, and its corresponding type, is rigorously structured.
+---+--------------------------------------------------------+ |TYP|Structured Body | +---+--------------------------------------------------------+
| Type | Structured Body |
|---|---|
+++ | CAPTURE START: Free-form comment. Start of Patch. |
CTL | Control Record / Block Separator. |
B66 | Specially-encoded, ASCII-encoded Binary representation of a line-oriented record. |
TXT | Specially-encoded, ASCII/Text representation of a charset letter or parser directive (e.g. lcommon= |
MAP | Follows TXT records and is followed by BIT recors which render the TXT values for each character visually. |
--- | CAPTURE END : Free-form comment. End of Patch. |
For this tutorial, we will examine the system file sysid:
- sysid
+++ CAPTURE START: CTL-FIL s0file BLK sysid TYP common EXT lesson SEQ 1 TXTlcommon=320 B66 1okachris hopkins<<<<<<<s<<<<<<<<< 01/04/98 12.16.05.b[[[[[[[[[ B66 17[[[[[[[[[[[[[[[[ B66 33[[[[[[[[[[[[[[[[ B66 49[[[[[[[[[[[[[[[[ B66 65[[[[[[[[[[[[[[[[ B66 81[[[[[[[[[[[[[[[[ B66 97[[[[[[[[[[[[[[[[ B66 113[[[[[[[[[[[[[[[[ B66 129[[[[[[[[[[[[[[[[ B66 145[[[[[[[[[[[[[[[[ B66 161[[[[[[[[[[[[[[[[ B66 177[[[[[[[[[[[[[[[[ B66 193[[[[[[[[[[[[[[[[ B66 209[[[[[[[[[[[[[[[[ B66 225[[[[[[[[[[[[[[[[ B66 241[[[[[[[[[[[[[[[[ B66 257[[[[[[[[[[[[[[[[ B66 273[[[[[[[[[[[[[[[[ B66 289[[[[[[[[[[[[[[[[ B66 305[[[[[[[[[[[[[[[[ CTL-FIL s0file BLK pubcware TYP common EXT lesson SEQ 2 TXTlcommon=320 B66 1o2-d<b#ib<#n[[[[[[[[[[[[[[[ B66 17[[[[[[[[[[[[[[[[ B66 33[[[[[[[[[[[[[[[[ B66 49[[[[[[[[[[[[[[[[ B66 65[[[[[[[[[[[[[[[[ B66 81[[[[[[[[[[[[[[[[ B66 97[[[[[[[[[[[[[[[[ B66 113[[[[[[[[[[[[[[[[ B66 129[[[[[[[[[[[[[[[[ B66 145[[[[[[[[[[[[[[[[ B66 161[[[[[[[[[[[[[[[[ B66 177[[[[[[[[[[[[[[[[ B66 193[[[[[[[[[[[[[[[[ B66 209[[[[[[[[[[[[[[[[ B66 225[[[[[[[[[[[[[[[[ B66 241[[[[[[[[[[[[[[[[ B66 257[[[[[[[[[[[[[[[[ B66 273[[[[[[[[[[[[[[[[ B66 289[[[[[[[[[[[[[[[[ B66 305[[[[[[[[[[[[[[[[ --- CAPTURE END :
For purposes of this tutorial, the following patch files have also been stored for your reference:
CTL Record
The CTL Record identifies the boundary between 320-word blocks in the PLATO File.
Example:
....+....1....+....2....+....3....+....4....+....5....+....6....+....7. CTL-FIL s0file BLK sysid TYP common EXT lesson SEQ 1
| Columns | Content | Description |
|---|---|---|
| 1-3 | CTL | (Field Identifier) |
| 4 | - or + | Partial Indicator for SOURCE |
| 5-7 | FIL | (Field Identifier) |
| 8 | (space) | (Field Separator) |
| 9-18 | <filename> | 1 to 10 character name of the file from which this patch was created |
| 19 | (space) | (Field Separator) |
| 20-22 | BLK | (Field Identifier) |
| 23 | (space) | (Field Separator) |
| 24-33 | <blockname> | 1 to 10 character name of the block within the file from which this patch was created |
| 34 | (space) | (Field Separator) |
| 35-37 | TYP | (Field Identifier) |
| 38 | (space) | (Field Separator) |
| 39-48 | <blocktype> | 1 to 10 character type of the block within the file from which this patch was created |
| 49 | (space) | (Field Separator) |
| 50-52 | EXT | (Field Identifier) |
| 53 | (space) | (Field Separator) |
| 54-63 | <extension> | 1 to 10 character describing type of the FILE from which this patch was created |
| 64 | (space) | (Field Separator) |
| 65-67 | EXT | (Field Identifier) |
| 68 | (space) | (Field Separator) |
| 69-71 | <seqnum> | 3-digit number identifying the original starting block sequence number of the sequence of blocks comprising this set of blocks. |
TXT Record
The TXT record varies by the type of block being processed.
CHARSET Type
The patch system uses the TXT records ALONE when constructing a character set.
| Columns | Content | Description |
|---|---|---|
| 1-3 | TXT | (Field Identifier) |
| 4-11 | char | (Field Identifier) |
| 12-14 | nnn | Decimal, 3-digit number of the character slot described by the values to follow |
| 15 | (space) | (Field Separator) |
| 16-78 | 8 octal values | The octal values to follow represent the “vertical slices” (columns) of the bitmap composing the character. Each octal value is 18-bits (one for each vertical position) of which the least significant 16 are used. |
A sample of the character set standard from lesson charsets:
....+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8 TXTchar 000 o000000,o000000,o000000,o000000,o000000,o000000,o000000,o000000 TXTchar 001 o000140,o001220,o001220,o001220,o001220,o000740,o000020,o000000 TXTchar 002 o017760,o000440,o001020,o001020,o001020,o000440,o000300,o000000 TXTchar 003 o000300,o000440,o001020,o001020,o001020,o001020,o000440,o000000 TXTchar 004 o000300,o000440,o001020,o001020,o001020,o000440,o017760,o000000 TXTchar 005 o000300,o000640,o001220,o001220,o001220,o001220,o000620,o000000 . . . TXTchar 123 o000000,o000000,o001460,o001460,o000000,o000000,o000000,o000000 TXTchar 124 o000000,o000000,o000000,o017620,o000000,o000000,o000000,o000000 TXTchar 125 o002000,o001000,o000400,o000200,o000100,o000040,o000020,o000000 TXTchar 126 o000740,o001020,o002310,o002450,o002750,o001040,o000700,o000000 TXTchar 127 o000000,o000000,o000000,o000000,o000000,o000000,o000000,o000000
Because these can be difficult to visualize, the patch file format provides for a visual representation of the resulting displayed character:
MAPchar 000 char 001 char 002 char 003 char 004 char 005 char 006 char 007 BIT BIT BIT BIT * * ** BIT * * * * BIT * * * BIT **** * *** **** *** * **** *** **** * BIT * ** * * * * ** * * * * * BIT ***** * * * * * ******* * * * BIT * * * * * * * * * **** BIT * * ** * * * * ** * * * BIT **** * * *** **** *** * ***** *** ***** BIT * * BIT ***** BIT BIT MAPchar 008 char 009 char 010 char 011 char 012 char 013 char 014 char 015 BIT BIT BIT BIT** * * ** ** BIT * * * BIT * * * BIT * *** ** ** * ** * *** ** ** *** *** BIT ** * * * * * * * * * ** * * * BIT * * * * ** * * * * * * * * BIT * * * * * * * * * * * * * * BIT * * * * * * * * * * * * * * BIT * * *** * ** ** *** * * * * * *** BIT * BIT * BIT ** BIT
TheMAPandBITrecords are ignored during patch processing.
COMMON Type
The format of the TXT record within a TYP of common is simply of the format:
....+....1....+....2.. TXTlcommon=<value>
where value is the length, in words, of the common values to follow.
In our example:
CTL-FIL s0file BLK sysid TYP common EXT lesson SEQ 1 TXTlcommon=320
The B66 record values that follow must describe 320, 60-bit words of storage.
B66 Record
Each lower-case character is the display-code representation of the six-bit binary values between 0 (zero) and 63 [decimal].
Special characters represent specific values of different types. For binary type blocks (discussed in this article)
1):
SOURCE Type
The SOURCE type line format is represented by a sequence of TUTOR line-oriented records:
CTL-FIL ncharset BLK -reminder- TYP source EXT lesson SEQ 2 B66*list symbols<<<<< B66*list mods<<<<<<<< B66*list eject<<<<<<< B66* << B66* #hwould be nice to delay adding a char until going to<<<<<< B66* the actual design page, so that pressing #hb#ha#hc#hk after<<< B66* typing the wrong letter wouldn#h7t stick in a (blank)<<<<<< B66* char for that letter.<<<<<<< B66* << B66* << B66* #hjust a reminder for some future date--there<<<<< B66* should be better integrity checks on the incoming<<< B66* charset info...a bad terminal memory address for<<<< B66* one character in a charset recently caused the<<<<<< B66* charset editor to bomb off with an execution error.<[ B66* << B66* --#hrick #hblomme #hjune 26, 1975[ B66* << B66******** don emerick icbd 11/05/76 13.26.55<< B66*#hhi marshall,<<<<<< B66* #hi got a long delayed request to make re the charset<<<<<<<<< B66*editor#h> a lot of my character designs depend on symmetry.<[ B66* <[ B66*#hwould it be possible to set up an option in the charset << B66*editor like the #h,make a copy of a character#h,, except that[ B66*the new option would allow us to reflect the #h,copied#h,<<<< B66*character thru the x-axis, the y-axis, or thru the origin#h/[ B66*#hit seems to me the point-for-point transformation routine<[ B66*would be quite simple to establish.<<<< B66* <[ B66*#hif this note should go to some else, please forward it.<<< B66* #hthanks, #hdon<< B66********<<
A line-end representation is a 12-bit sequence of ZEROs.
COMMON Type
For COMMON entries, each B66 record identifier is followed by a six-digit decimal number describing the offset
at which the value that follows, is to be placed.
In our example of file s0file / common sysid:
B66 1okachris hopkins<<<<<<<s<<<<<<<<< 01/04/98 12.16.05.b[[[[[[[[[ B66 17[[[[[[[[[[[[[[[[ B66 33[[[[[[[[[[[[[[[[ B66 49[[[[[[[[[[[[[[[[ B66 65[[[[[[[[[[[[[[[[ B66 81[[[[[[[[[[[[[[[[ B66 97[[[[[[[[[[[[[[[[ B66 113[[[[[[[[[[[[[[[[ B66 129[[[[[[[[[[[[[[[[ B66 145[[[[[[[[[[[[[[[[ B66 161[[[[[[[[[[[[[[[[ B66 177[[[[[[[[[[[[[[[[ B66 193[[[[[[[[[[[[[[[[ B66 209[[[[[[[[[[[[[[[[ B66 225[[[[[[[[[[[[[[[[ B66 241[[[[[[[[[[[[[[[[ B66 257[[[[[[[[[[[[[[[[ B66 273[[[[[[[[[[[[[[[[ B66 289[[[[[[[[[[[[[[[[ B66 305[[[[[[[[[[[[[[[[
In the example - there are sixteen, 60-bit words described per line.
plato/cdc.io/patch.structure.txt · Last modified: 2023/11/26 07:41 by Site Administrator