From fractals, over the hills and far away...

Talk about non-Acorn classic computers/hardware/software here (including retro consoles)
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From fractals, over the hills and far away...

Post by Coeus » Sat Jun 16, 2018 12:41 pm

I'm not at all sure which forum this belongs in but....

Long ago I had the experience of starting to read one entry in an encyclopaedia, which referred to another and that to another and before long I would be reading about something very different from what I started out looking up. Of course, since then I have had the same experience with Wikipedia and it can be a property of the WWW in general.

Recently I had been following two threads on here about the Mandelbrot: 12-second Mandelbrot rendering on the BBC Master! and Border tracing Mandelbrot generator for the Beeb. So I searched to see what's out there and found, of course, various fractal generators for my mobile phone one of which looks like it uses the same kernel as demonstrated in Re: 12-second Mandelbrot rendering on the BBC Master! - I currently have Fraksi and Fractview for Android.

I also came across a program called Fracint which seemed to be very well regarded back in it's time and, as far as I can tell, uses integer arithmetic with a scaling convention that turns it into fixed point. There is supposed to be a Unix port but it seems to be targeted at a very old compilers and would not compile on modern gcc without changes so I thought I'd give the DOS version a go just to see what it's like. Running on Linux that took me into the world of DOS emulators including DOSBOX and the forked DOSEMU available in its original version and the newer fork called DOSEMU-2 as well as just running DOS in VirtualBox.

Then someone posted a link to a fast Mandelbrot generator running on the Amstrad CPC which I had never used BITD so I had a play with Thomas Harte's ClockSignal emulator. That got me interested in what else was out there in the way of CP/M emulators. Again, looking for things that would run on Linux I came across z80pack by Udo Munk which seems very neat and tidy. One obvious difference between an emulator like that and emulator for a specific system is that z80pack does not emulate any graphics hardware or indeed any kind of display at all. It assumes it will be run from a terminal emulator window. That all seems in keeping with way CP/M works, assuming it has a dumb terminal and therefore not including any full-screen applications itself (the editor is a bit of a learning curve), but allowing applications that run under it to indulge in full-screen control using the relevant codes if they so wish. That lead me to the game of transferring files between Acorn CP/M disks images and IBM-3740 (8" floppy) disk images leading to my post about Acorn CP/M formats where I found that others here had previous discovered z80pack. I also knew J. G. Harston was a bit of a CP/M expert before but the extensive info on certainly cements that. Through his CP/M pages I found YAZE-AG which has many similarities with z80pack but also comes bundled with some interesting disks and has the feature to be able to dynamically turn a host directory into a virtual CP/M disk.

One of the disks in the YAZE set is a Z80 instruction set exerciser and the B-Em Z80 tube implementation fails its test, though I have not yet looked into whether these are just undocumented subtleties that normal programs would not encounter - I suspect that probably is the case.

Anyway, it's been an interesting journey.

P.S. A few things I noticed:

1. For DOS, especially, there is much more interest in old games that other kinds of old software.
2. CP/M seems to have a community around it, still, with lots of stuff out there.
3. The CP/M trail included several people who have died. CP/M is older, but but by a huge amount, surely?
Last edited by Coeus on Sat Jun 16, 2018 1:00 pm, edited 2 times in total.

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Re: From fractals, over the hills and far away...

Post by BigEd » Sat Jun 16, 2018 12:54 pm

Human knowledge is a fractal tree... it seems very worthwhile to keep exploring new branches!


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