[Oberon] Re (2): Copy or reinstall A2?
joerg.straube at iaeth.ch
Wed Jul 21 19:08:04 CEST 2021
I fully agree that the word "ISO image" may be confusing.
Generally an "image" is more or less a 1:1 copy of the source medium.
Originally, the source medium was a CD/DVD. Hence the filesystem was fixed to ISO9600.
Later the source medium could also be hard disk, and it was "just" a 1:1 copy of a HD. The filesystem is "in most cases" NOT ISO9660 but ext1, NTFS, HFS+, OberonFS or so...
An important role in an "ISO image" is the MBR, the first sector of the image:
- the MBR MAY contain an optional bootloader. The bootloader decides whether the image is bootable or not.
- the MBR holds the partition table. The partition table store info on the filesystems in use per partition.
From: Oberon <oberon-bounces at lists.inf.ethz.ch> On Behalf Of Liam Proven
Sent: Wednesday, July 21, 2021 5:08 PM
To: ETH Oberon and related systems <oberon at lists.inf.ethz.ch>
Subject: Re: [Oberon] Re (2): Copy or reinstall A2?
On Tue, 20 Jul 2021 at 14:32, <peter at easthope.ca> wrote:
> From: Liam Proven <lproven at gmail.com>
> Date: Mon, 19 Jul 2021 09:54:12 +0200
> > Doesn't anyone run A2 directly on x86?
> I Have but LinuxA2 is convenient & flexible.
> A Linux machine and an A2 machine can be networked. Otherwise have the
> two systems on one machine. Linux with LinuxA2, Windows with WinA2,
> Did you see my 2nd reply?
I did see it, yes. I did not respond because I was not really sure how to respond; I am sure what you are saying is true, but it was not really an answer to my question. :-)
I think building a new installation from source is not really an option for me at the moment -- I am still learning A2 and Oberon itself and to be honest I have not got very far at all yet. Getting it working on a physical computer was an exercise in this process.
What I have learned since I did it is a more specific instance of something I already knew from working with classic Macintosh computers, decades ago:
 Just because something is called $filename.ISO does not mean that the contents are necessarily an ISO-format file. There are multiple non-PC OSes out there that can handle CD drives and which can store information on CDs, and be installed from CD, but using their native filesystem on CD media. Classic MacOS wrote HFS and HDS+ CDs and they can be read and booted from on a classic Mac, but they are not ISO9660 media nor any other variant of High Sierra, El Torito or any other optical-medium filesystem.
 Tools which can write an ISO file to a USB flash drive may completely fail when presented with an ISO file that does not contain an ISO 9660 filesystem. They will write it to the USB medium, but the result will not be bootable or readable. The ISO file may boot a virtual machine successfully, but it will not boot if written to USB.
(Examples: AROS, the FOSS Amiga OS.)
I also recently upgraded the BIOS on my Thinkpad W500 and although the file was called something.ISO, it wasn't an ISO file and it wouldn't work either written to a USB key, nor copied onto a multi-boot tool on USB. (I use Ventoy:
https://www.ventoy.net/en/index.html It's very useful and a huge
But when I burned the IBM bootable updater to an actual CD -- something I haven't done in many years -- it worked perfectly, booted a modified copy of IBM PC DOS, and updated my firmware correctly.
Looks like an ISO; is not an ISO. It's just _called_ ISO.
Well, looking back, the A2 ISO images may be the same. I think they're called ISO but they contain A2 filesystems. I could not get it to boot from USB, but I never tried writing it to floppy. I will do that next time and I may have more luck.
> Incidentally, the Fox compiler in A2 is a cross compiler. A
> relatively small investment of making a back end for the RISC machine
> would allow Fox to produce RISC object code.
Which particular RISC machine do you have in mind?
I was aware of this, yes, and I was considering trying to produce an experimental ARM executable and seeing if I could run it on a Raspberry Pi. I know it will not have any I/O without drivers for USB etc., but maybe if I could get as far as writing something to the screen, that would be progress.
I have also found another interesting very low-end RISC board recently that might be of interest as a possible target for Oberon.
It is called a TTGO VGA32 from LilyGo.
The product page is very unhelpful and uninformative, but a helpful poster on Facebook explained what one is to me:
The TTGO VGA32 is an ESP32 with interfaces for PS/2 mouse and keyboard, and 8 or 16 color VGA, on specific lines. The software is a base system called FabGL that acts as a base on the ESP32. It provides numerous facilities for emulation of terminals, emulation of several vintage processors, and for being directly programmable as a stand-alone system.
A VGA32 can be built up using an ESP32 on a breadboard, following the wiring on the FabGL github pages, or bought as a complete system from LilyGO through one of their various distribution channels. The LilyGO TTGO VGA32 v1.4 sells for less than the price of the connectors and the ESP32 at retail, so it's an easy way to go, but if you have spare VGA and PS/2 connectors around, making your own isn't difficult.
Here's the link to the FabGL github page:
The ESP32 is a widely-used 32-bit RISC chip. This is a dual-core model. It costs about $3 in bulk and it's normally used for running a
Wifi+TCP/IP stack. There are versions with both Xtensa and RISC-V
I know it from a learners' home computer, the BASIC*Engine:
This is a 32-bit RISC computer, with VGA out, PS/2 keyboard and mouse, about ½MB of RAM and 4MB of Flash, for $10 per unit -- less than the cost of the connectors if bought in isolation.
It may be underpowered for A2 but I think it could be a good target for Oberon.
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