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View and the Amiga

by Carl Read - July, 2000

Or more correctly, View and my Amiga and getting REBOL View 4.1 Beta to behave on it. That said, what's in this article should apply to most Amiga users of View 4.1.

My first experience of View wasn't too happy with most of the example scripts not behaving and full system crashes being the norm, though I eventually worked out it was my GFX card causing these problems. (See the end of the article.) Once this was sorted out View became very stable, though there are still a few problems that could trip up first-time Amiga users of View, so these will be the focus of this article.

Opening Window Bug

There's a major bug in Amiga View 4.1 which will cause a total lock-up of your system if a script attempts to open a window that's larger than the screen. What happens when you run such a script is you get the following error message...

** User Error: Unable to open window (10).
** Where: show scr-face
if new [do-events]

and then your Amiga will lock up when you try and exit the REBOL console. Making your screen bigger is the obvious solution to this till the bug's (hopefully) fixed with the next release of View. (RT know of it.)

This bug could be a killer for Amiga users running smallish Workbench screens though as the first use of View automatically runs the Demo which opens a largish window. For instance, this window will not fit on a 640x512 screen, (as I found out when I tried View on a default Amiga setup. Well, a bit bigger than default - the default's 640x256...), which could mean some users' first experience of View would be an error message followed by a lock-up and the need to reboot. I'd recommend at least an 800x600 screen to get you started and a 1024x768 one for some of the larger windows you'll encounter in the REBOL examples' library.

The View Demo

As mentioned above, View comes with a Demo which allows you to set some preferences such as your email address, to stop the demo automatically running when you start REBOL and to allow you to "Check Reb Site". This latter option will apparently download a heap of stuff and run a mix of demo scripts. I say apparently because it currently needs (I've been told) 22MBs of memory to run and I've only 18 total so all I get is an out-of-memory message.

The main problem with not being able to run the demo is you end up with a View without any docs or examples, which is what I assume you get if you can run it. (There's not even a Readme with the archive.) You can however get the library of example scripts from the REBOL site, (they're available packed in a REBOL .rip script so you can download them as a single file and use REBOL to unpack them), and there's a page on the site saying which of the examples are View scripts. You'll also need the "View User's Guide" from the site which at the moment is just a single web-page, but that should be enough to get you started. Whether that is more or less than you'd get if you can run the Demo I wouldn't know, but checking the REBOL site regularly for new and updated information is something I'd recommend anyway. The info on the site is constantly improving.

My GFX Card Problem

As mentioned at the start I had problems with View 4.1 and my Amiga GFX-card. The card is Ateo Concepts' Pixel64 running Picasso96 on my A1200 and I had my Workbench screen at 256 colours as I prefer to run apps on their own screens. (It saves wasting memory on icons and a few bland utilities.) And since View defaults to opening its windows on the Workbench, for me it was originally opening them on a 256 colour screen and it was this which was causing me problems and crashes with every View script I tried. Switching my Workbench screen to 16bit or better fixed all these problems, as well as making scripts run a bit faster. (I'm unsure if you can force View to use its own screen, however, I haven't looked into this.) I'm pretty sure this is a specific Pixel64/Picasso96 problem as View seems fine on AGA displays. However, View's the only software I've had this kind of problem with so whether the bug's in View, Pixel64 or Picasso96 I wouldn't like to say.

Memory Use

Depending on what you're doing with it, View can use a lot of memory, so for those who need to cut down on Amiga memory use, don't forget that removing large backdrop pictures from your Workbench screen and windows can reclaim you quite a bit RAM, especially when using 16bit or higher resolutions. I know it's sad to see the pretty pictures go, but that's life on under-nourished machines I'm afraid. Sniff...

Despite a shaky start to using View on the Amiga, I now find it to be very stable to develop scripts on. Expect it to only get better.

Postscript:

Since writing the above I've found you can give REBOL its own screen. (Thanks to Boleslav Brezovsky for posting the info to a REBOL mailing list.) All it requires is for you to edit your user.r file to include the "exclusive-colors..." line as shown below and, optionally, the "dither..." and "monochrome..." lines if you want dithered graphics and/or a grey-scale screen. Boleslav suggests not including the lines you don't want instead of using "false" which apparently doesn't work as it should, though I've not tested this.

system/view/screen-face/options: [

    exclusive-colors: true  ; REBOL on own screen

    dither: true            ; turns on dithering

    monochrome: true        ; REBOL in b/w

]

Note the Console will still load on your Workbench, but now when you run a View script you'll be prompted with a standard Amiga screen-requester to select the screen of your choice. This screen will remain open as long as you keep the Console open, so the screen-requester only pops up once per REBOL session.