Archive for March, 2011

A while ago, I found this site with abandonware.
Bits and bytes, forgotten, lost in history. Among the files on this site,
there is Xenix. A UNIX-os, back in the days, by Microsoft.

Long forgotten times, times, when computers were still interesting
(and I was still wearing diapers)

Afin…. monday, this Xenix OS was broad up in a conversation
at Stack, and so, I decided to try to get the damn thing working.

Not as easy as it looks like, to get the Xenix version for the 8086
working. Even though, modern x86 hardware is supposed to be
compatible with the original IBM-PC, none of the emulators seems
to understand what to do when I feed it the disk images.

One of the reasons, perhaps, is the fact the floppy images are
360k images, and the emulators only understand 1,44 MB images.

I have tried virtualbox, qemu, bochs and PCem, without luck.
PCem, well… it’s a windows app, but it runs in wine. PCem
seems to emulate older, real hardware, or tries to. It supports
various machines, and BIOS files from the original hardware.

It also includes AMI 386 and AMI 486 with BIOS files….
Oh… memories… seeing the AMIBIOS again, the way it
used to look on my first computer…. but booting Xenix….
no, that’s too much to ask….

Some note to make, as it seems, the boot loaders do
load in some of these emulators, but the boot loader
seems unable to load the kernel. The kernel file is
available on the floppy image

To mount such an image, use

mount N1 test -o loop -t sysv

For one part, I suspect these old images possibly do not
respect the boot signature, and therefore mark the image
as non-bootable. And for the part the boot-loader does
work, I suspect the emulation of the floppy controller is
not completely accurate, as in, possible timing issues.
But this is just a wild guess….

Anyways…. I have found an emulator that passes this
point, and boots the kernel correctly. The emulator that
works is an emulator specific for the IBM PC 5150,
and that seems to do the trick…. but now…. I have to
find out how to swap the disk image to insert the 2nd
disk when Xenix asks for it.

Well…. I posted about the VGA adaptor for the BeagleBoard.
I’ve looked around on this site and found this

And yes, problems regarding USB stability, that’s the reason
I haven’t been using my BeagleBoard as intended.

Even though I assumed this was a kernel issue, as this was
suggested by various sites discussing the installation process.

My BeagleBoard is still catching dust, somewhere in a dark corner. I never used it, which is kinda sad, isn’t it.

Well, it only has a digital video output, so I cannot connect a normal vga (crt) monitor to it. (Of which I have a few in the basement)

So, I’ve obtained a used flat screen with DVI-D input, back in the days I still worked at Unilogic, and they were replacing their monitors.

Unfortunately, it’s had 5:4 aspect ratio, and it’s native resolution is 1280×1024, which is not supported by the BeagleBoard. Well, it is supported, but with a refresh-rate of 50Hz, which is not supported by the monitor.

Well… I am using this monitor at my desktop nowadays… But meh…. those modern flat monitors with non-standard (non 4:3) aspect ratios, and things like a ‘native resolution’.

A normal CRT monitor would be much simpler… they usually have the same aspect ratio, and the image doesn’t get distorted when running at a lower then maximal resolution.

But…. there is no VGA output on the BeagleBoard… so… I was googling again…. and I found a Hawkboard.
Another ARM board, and it has a VGA-out. Looking at it’s schema, I saw it used a THS8135 to provide in VGA output. So, I started googling if there was a converter for the BeagleBoard using this chip…. but in stead I came accros this

Very simple circuit… this should do the trick. Why should it be complicated?

So, why are HDMI(DVI-D) to VGA converters to expensive? This circcuit that I’ve found is just a few resistors and two transistors.
So, this circuit should costs about 4 euros!!! Why are those converters a few hunderd euros?  (Okay, thet are connected to the DVI-D port, and this circuit goes to the LCD interface….)

So, I guess I should get some resistors, transistors and a soldering iron, much cheaper then a hdmi to vga converter or a new monitor…