Re: How is U2 different from XyWrite?

[junja junja@xxxxxxxx]

Another stab at replying to:
> Both native XyWrite and the entries in U2 are
> written in XPL. So how are they different?

They differ in the feature sets they offer.

In answer to:
> Does U2 "translate" the XyW output so it can be
> understood by the "external programs?" "Translate"
> commands from the "external" programs so XyW can
> respond to them? Or is its fundamental task
> something different?

The underlying situation is that the software in a
running machine is arranged in memory in logical
layers:
- bottom layer the resident, more or less
 unalterable, ROM bios code
- next the OS - Dos in the case of Xy4
- next the program - Xy4 for instance
- above that any scripts (like U2) and of course
 any data files the user is working on.

Each of these layers adds a set of features to the
machine's capacities. To create its set, it
relies on the resources in layers below it. Put
another way, each layer "hosts" the layer above it.
Or, equivalently, each layer is written in the
language of the layer below it.

And each layer is more specific than the one below it.
Xy4 is general word-processing while U2 is a set of
operations one can do in Xy and does often enough to
make it worthwhile have the program do them rather
than the user.

The point about "external programs" concerns
features like U2's use of the Windows clipboard.
It's not a matter of a mish mash of programs
jostling together, it's one of specific features -
copying and pasting between Xy4 and Windows.
John


John H. Kessel wrote:
> When I posted my first questions on August 4, I said I was a low-end
> user. Let me
> amplify that. I have read that John Tukey distinguished data analysts from
> statisticians. In the same spirit, I am a program user, not a
> programmer. Right now,
> for example, I learn a little bit more about U2 each time I reread the
> documentation
> and especially when I use a command for the first time, but in the end
> it doesn't add
> up to very much. All I need to know are how to issue the commands, and
> have some
> general sense of what a program does.
> I spelled this out because I want to ask a question so general that a
> complete response
> would require hundreds, if not thousands, of pages. Both native XyWrite
> and the
> entries in U2 are written in XPL. So how are they different? More
> specifically, we are
> dealing with at least five entities: original XyWrite 4.016, U2, Virtual
> Dos Machine, an
> Operating System, and other applications that run under that OS .
> PARSEFRM.DOC
> explains that U2 makes XyWrite much more efficient by loading all needed
> commands
> at one time, thus preserving memory. But there has to be interaction
> between XyW and
> VDM, the OS, and any other applications involved. Does U2 "translate"
> the XyW output
> so it can be understood by the "external programs?" "Translate" commands
> from the
> "external" programs so XyW can respond to them? Or is its fundamental
> task something
> different?
> All I am looking for is a reply of paragraph length. I understand that
> this would involve
> gross simplification of intellectual work that has gone on for more than
> a decade. But
> it would help me begin to understand what's going on.
>
> Thank you.
>
> John
>
>
> John H. Kessel
> Ohio State University
> kessel.1@xxxxxxxx