[NTLK] Converting NewtonBooks to ePub

[Perley Mears]

This conversation has me wondering about a Calibre plug-in for conversions,
making it easier to enjoy one's ebook library on Newton's.

Perley

Perley Mears
perley at mears.us


On Wed, Feb 25, 2026 at 8:29 AM J Caffiney <caffiney at gmail.com> wrote:

> Matthias,
>
> Thanks, this is exactly the kind of detail I was hoping someone had. Your
> breakdown of the style run structure matches what I've been able to piece
> together.
>
> The style runs were the main puzzle (figuring out that the numbers are
> character counts and not byte offsets into the text string), with each
> count/style pair applied sequentially. Once that clicked, most of the
> formatting came through.
>
> Good point about the more complex features. I've been focused on the common
> case — text, styles, chapters, basic metadata. Haven't run into embedded
> scripts or forms yet, but I'd guess those are edge cases in the UNNA
> library.
>
> I'll let the community weigh in on the interest question. I'm going to try
> to finish it for my own books either way.
>
> -J
>
> On Wed, Feb 25, 2026 at 8:11 AM Matthias Melcher <m.melcher at robowerk.de>
> wrote:
>
> >
> > Just to give a little technical overview. The file header looks like
> this:
> >
> >   signature: 'package0,
> >   id: "xxxx",
> >   flags: {},
> >   version: 1,
> >   copyright: "\uFFA9\u1995 Cortland Publishing. All rights reserved.",
> >   name: "Midsummer Night:JonC",
> >   size: 242188,
> >   creationdate: -1411759343,
> >   modifyDate: -1411759343,
> >   reserved3: 0,
> >   directorySize: 284,
> >   info: "Newton\u2122\u ToolKit Package \u00A9\u 1992-1994, Apple
> > Computer, Inc.\u0000\u",
> >   part: [
> >     {
> >       offset: 0,
> >       size: 241904,
> >       type: "book",
> >       flags: {type: 'nos, Notify: true},
> >       info: "book",
> >       data: {
> >         book: {
> >           version: 1,
> >           isbn: "Co9505122133",
> >           title: "A Midsummer Night's Dream",
> >           shortTitle: "MND",
> >           copyright: "\u00A9\u 1995 Cortland Publishing",
> >           author: "William Shakespeare",
> >           publisher: "Cortland Publishing",
> >           data: {},
> >           contents: [
> >             Ref_23,
> >             Ref_25,
> >             :
> >             : ... and many more
> >
> > where Ref_23 for example is
> >
> > {data: "Title Page", layout: 2048}
> >
> > and Ref_25 is
> >
> > {
> >   data: "\n\nA Midsummer Night's Dream\nby William
> Shakespeare\n\n1596\n",
> >   styles: [
> >     2, {family: 'espy, face: 0, size: 10},
> >     25, {family: 'newyork, face: 0, size: 18},
> >     24, {family: 'espy, face: 0, size: 10},
> >     1, {family: 'newyork, face: 0, size: 12},
> >     4, {family: 'espy, face: 0, size: 10},
> >     2, {family: 'newyork, face: 0, size: 12}
> >   ],
> >   layout: 4,
> >   viewJustify: 2
> > }
> >
> >
> > So there is a lot of plain text, and the formatting is defined by the
> > "style" tag. Here in the title, we have two characters in the Epsy font
> > with 10 pixel height ('\n\n' are two "carriage return/new line"
> characters,
> > just like on the type writer.
> >
> > Then we have 25 characters in NewYaork forny an 18 pixels high: "A
> > Midsummer Night's Dream", and so on.
> >
> > "viewJustify: 2" means centered on the page. This information can be
> found
> > in the Newton Programmers Guide.
> >
> > So all in all, this is a pretty readable format. No compression, no
> > encryption - at least not in the files that I looked at.
> >
> > Newton Books can in theory become quite complex. The format allows
> > embedding scripts and entire applications. You can have forms for the
> user
> > to fill out, and so much more. But I doubt that this has been used very
> > often. Extracting pure text, attributes, and maybe embedded images is not
> > too complicated. How big is the interest by the commuity to have a
> > book-to-ePub converter?
> >
> >  - Matthias
> >
> >
> >
> > ----------------------------------------------------------------------
> >
> > https://newtontalk.net
> > https://bitbang.social/@newtontalk
> > https://twitter.com/newtontalk
> >
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>
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