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Reverse engineering old printer drivers->

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First post, by Peter Swinkels

Posted on 2022-12-28, 13:14

Peter Swinkels Offline

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Rank: Oldbie
Posts: 541
Joined: 2005-11-16, 20:32
Location: The Netherlands

Hi,

I have been examining the file formats for a program called Cartooners for MS-DOS (originally for the Apple IIGS) from 1988 by ITDA/Electronic Arts. Among the files in the file archives that come with its installation disk(s) are several *.lpt files all relating to printers. These files contain what appear to be printer control codes, while I have found some rather long and technical documentation for HP PCL (Printer Control Language) I am unsure of what exactly the date in these files represents. Can anyone who knows more about printers point me in the right direction as to what exactly these *.lpt files contain?

EDIT:
A link to my Google Drive folder containing a zip file with the drivers in question:
https://drive.google.com/drive/folders/1jARH2 … 5ZI?usp=sharing

Here's a summary of what little I found out. All files are of the same size and appear to have the same data at the same offsets:

1[Printer Drivers]
2
3[File Information]
4Endianess: ?
5Extension: *.lpt
6
7[File Layout]
80x00	DWORD		Signature.
90x04	0x27 BYTES	Printer model name padded with 0x00 bytes.
100x2C	BYTE		Unknown.
110x2D	WORD		Unknown.
120x2F	BYTE		Null.
130x30	WORD		Unknown.
140x32	WORD		Unknown.
150x34	WORD		Unknown.
160x36	WORD		Unknown.
170x38	BYTE		Unknown.
180x39	BYTE		Unknown.
190x3A	BYTE		Unknown.
200x3B	BYTE		Unknown.
210x3C	BYTE		Unknown.
220x3D	BYTE		Unknown.
230x3E	BYTE		Unknown.
240x3F	BYTE		Unknown.
250x40	BYTE		Unknown.
260x41	BYTE		Unknown.
270x42	BYTE		Unknown.
280x43	BYTE		Unknown.
290x44	BYTE		Unknown.
300x45	BYTE		Unknown.
310x46	BYTE		Unknown.
320x47	BYTE		Unknown.
330x48	BYTE		Unknown.
340x49	0x10 BYTES	Null.
350x59	BYTE		Unknown.
360x5A	BYTE		Always 0x1B - Probably a PCL command.
370x5B	BYTE		Unknown.
380x5C	BYTE		Unknown.
390x5D	BYTE		Unknown.
400x5E	BYTE		Unknown.
410x5F	BYTE		Unknown.
420x60	BYTE		Unknown.
430x61	0x09 BYTES	Null.
440x6A	BYTE		Unknown.
450x6B	BYTE		Always 0x1B - Probably a PCL command.
460x6C	BYTE		Unknown.
470x6D	BYTE		Unknown.
480x6E	BYTE		Unknown.
490x6F	BYTE		Unknown.
500x70	BYTE		Unknown.
510x71	WORD		Null.
520x73	BYTE		Unknown.
530x74	BYTE		Appears to be a boolean. (0x00 or 0x01 only.)
540x75	BYTE		Unknown.
550x76	BYTE		Unknown.
560x77	BYTE		Unknown.
570x78	0x06 BYTES	Null.
580x7E	BYTE		Unknown.
590x7F	BYTE		Unknown.
600x80	BYTE		Unknown.

…Show last 22 lines

610x81	BYTE		Unknown.
620x82	BYTE		Unknown.
630x83	BYTE		Unknown.
640x84	BYTE		Unknown.
650x85	DWORD		Null.
660x89	BYTE		Unknown.
670x8A	BYTE		Unknown.
680x8B	BYTE		Unknown.
690x8C	BYTE		Unknown.
700x8D	DWORD		Null.
710x91	BYTE		Unknown.
720x92	BYTE		Unknown.
730x93	BYTE		Unknown.
740x94	BYTE		Unknown.
750x95	DWORD		Null.
760x99	BYTE		Unknown.
770x9A	BYTE		Unknown.
780x9B	BYTE		Unknown.
790x9C	BYTE		Unknown.
800x9D	DWORD		Null.
810xA1	BYTE		Unknown.

Do not read if you don't like attention seeking self-advertisements!

Did you read it anyway? Well, you can find all sorts of stuff I made using various programming languages over here:
https://github.com/peterswinkels

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