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I was looking at the Atari Word Processor which could hold only about one or two pages in 48k memory due to it requiring DOS to be loaded along with the relatively large program itself.

That led me to wonder... on a typical Z80 or 8080 CP/M machine of the era, how much could WordStar hold?

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    I don’t have the answer, but WordStar would swap text out to disk if it couldn’t fit a document in memory, avoiding the problems Atari Word Processor had (as long as the current disk had enough available storage). Commented Nov 1, 2022 at 12:38
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    And “typical”? More interesting with the full 64 kb Commented Nov 1, 2022 at 12:58
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    Speedscript also runs on Atari 8-bit machines. I think it allowed over 20 pages on a C64.
    – Brian H
    Commented Nov 1, 2022 at 15:40
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    One of the killer features for a text editor, before the era of virtual memory anyway, was being able to edit documents larger than physical memory. There's quite a few ways to manage it. WordStar was such an editor, and I have little doubt that accounted for some its popularity. (Not just as a word processor, it was very popular as a general-purpose editor too.)
    – RETRAC
    Commented Nov 1, 2022 at 23:50
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    @another-dave but it wasn't universal. I certainly had files too big for MSDOS's EDIT, and had to use Norton Editor
    – Chris H
    Commented Nov 2, 2022 at 15:16

3 Answers 3

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I wrote at least one manual of about 20 pages in about 1986 on CP/M WordStar 3.3, using a Microsoft Z80 Softcard plugged into an Apple IIe. That would swap text in or out to floppy disk from time to time, especially when you jumped to the far end of the document, but it was perfectly usable. The maximum size in-memory wasn't terribly meaningful with WordStar, it was intended to swap and did it automatically and reliably.

Maximum document size would have been half the available space on the floppy that held the document by default. You could put the swap space on another drive, but that wasn't the default. If you had a big hard disc, there was also a limit of 8MiB, set by the CP/M file system.

The Apple II 5.25" floppies had pretty limited capacity (143 KiB, not altered by CP/M IIRC). I was working with about 65 columns, and printing on an Apple Dot Matrix Printer, probably using about 55 lines per page, for about 3.5KiB per page, so 20-page documents would have taken about half a floppy's capacity and would have been close to the default limit on this setup.

With higher-capacity drives, maximum document size would increase. I don't know what "typical" floppy capacity for CP/M would be: the Apple II version is the only one I used.

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  • Though the question is asking explicitly not about maximum document size (which I guess would be maximum file size on the floppy/harddisk, and having multiple documents e.g. for each chapter wasn't a problem), but about pages in memory. For whatever reason.
    – dirkt
    Commented Nov 1, 2022 at 13:15
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    @dirkt: That's not very meaningful with WordStar. Commented Nov 1, 2022 at 13:18
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    @dirkt in practice with WordStar the maximum document size was half the available space on disk (because of the additional swap files). Commented Nov 1, 2022 at 13:57
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    @Maury a 64K system would have more than 10K of free room: the 45K requirement includes room for text editing. WordStar would refuse to start if it only had room to load itself. Commented Nov 1, 2022 at 15:47
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    @dirkt, the document’s swap file was always created on the same disk as the document. Placement was not configurable. On a two-floppy system you kept WordStar in one disk and put the document on the other. Commented Nov 2, 2022 at 6:49
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According to the installation manual at http://www.bitsavers.org/pdf/microPro/Wordstar_3.0/Wordstar_3.0_Installation_Manual_May81.pdf WordStar requires 45 kb to be able to work on a 80x24 display.

A 64 kb machine has 19 kb more, so at least that.

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    Same manual, page 1-1, about using on a single floppy system: "... and leave two times the size of the biggest file you will want to edit as unused space on the disk. "
    – UncleBod
    Commented Nov 1, 2022 at 13:14
  • That said it is an astonishing program. You should try writing a non-trivial document in it (even though you might want a faster disk). Commented Nov 1, 2022 at 13:26
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    @ThorbjørnRavnAndersen what's so special about it? Commented Nov 1, 2022 at 13:51
  • @OmarL The same as for next to all early implementations of anything - it was the jump from none to one. You will hear all the same stories about Apple Writer, despite it's cruel way of display and input. It's the revelation of editing a text in full screen, jumping around inserting and deleting effortless.
    – Raffzahn
    Commented Nov 1, 2022 at 15:46
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    @ThorbjørnRavnAndersen Not sure what point you want to make by initiating a A is better than B discussion. There have been books written on the C64, so some author using some package doesn't make it better or worse. (Not to mention, that according to your link RRM used DOS and Wordstar 4.0. not really the one the question asks about. There are huge differences between original 8080 wordstar and much later 4.0 on DOS)
    – Raffzahn
    Commented Nov 1, 2022 at 17:08
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As mentioned, WordStar swapped memory to disk during operation, so the document size was not dependent upon free RAM (outside of a basic free RAM requirement for the program). The larger the free RAM, the less often you had to swap to disk.

That suggests that the maximum document size was pegged to somewhere around 1/2 of disk capacity, since the disk has to hold both the original document, and the swapped version.

Mind, the swap file could be stored on a separate disk. In a typical 2 Disk system, you'd probably have the document in the B drive, and the CP/M, WordStar install in the A drive. With the swap file on the A drive, you'd have all that free space over and above CP/M and WordStar, which is quite likely less than half the disk, for the swap file for the larger file on the B drive.

256K was a common disk size, obviously densities improved, but 256K is good enough for a ball park. You could probably get a working system with 180K free on the disk (that's a guess). A page of text is 80 characters (10 characters per inch, 8 inches wide) by 60 lines (6 lines per inch, 10 inches long). Go double spaced, that 30 lines. That's 80 * 30, 2400 characters per page. 180K / 2400, 76 pages.

Ample space for a wide range of tasks. If you're working on a book, however, probably going to be 1 disk per chapter.

All told, though, beats a typewriter.

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    Probably worth mentioning that at least when talking about the CP/M version of WordStar it wasn't uncommon to use 8" floppy drives with CP/M systems so the max filesize could be quite a bit larger than with 5.25" disks (up to 1.2MB for DS/DD drives available from 1977 on).
    – mnem
    Commented Nov 2, 2022 at 3:56
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    Comments in the accepted answer say that the swap file is automatically created on the disk with the data file. Evidence of configurable nature would be very helpful.
    – RonJohn
    Commented Nov 3, 2022 at 4:24

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