[SATLUG] vi as a hex editor/file transfer

Carl Muellner carl.muellner at gmail.com
Fri Feb 18 21:25:32 CST 2011

Geoff -

    Go back to the basics,  If need be, get a USB-to-Serial converter,
connect the semi-state-of-the-art
system to an ancient dinosaur of a system and use uucp to dump the file

     I have had to resort to something similar to that quite a number of
times in the past, like over a serial console connection to an otherwise
non-connected system.  Not fast, not pretty, but effective.

     Good luck.

   -  Carl

On Fri, Feb 18, 2011 at 12:00 PM, <satlug-request at satlug.org> wrote:

> ------------------------------
> Message: 5
> Date: Fri, 18 Feb 2011 11:18:53 -0600
> From: Geoff Edmonson <w5omr at att.net>
> Subject: [SATLUG] vi as a hex editor/file transfer
> To: SATLUG <satlug at satlug.org>
> Message-ID: <4D5EA9FD.4000104 at att.net>
> Content-Type: text/plain; charset=windows-1252; format=flowed
> I've kicked, screamed, bit*hed, moaned and groaned about learning the
> dreaded editing program "vi". (even typing those two letters makes me
> shudder!)
> however... I've found something it's useful for...
>    Using vi as a hex editor
> Sometimes I find it useful to switch to hex mode when editing a file in
> vi. The command for switching is not very obvious so thought I’d share…
> So, open a file in vi as usual, hit escape and type:
> |:%!xxd| to switch into hex mode
> And when your done hit escape again and type:
> |:%!xxd -r| to exit from hex mode.
> The REASON I needed a hex editor is that, as part of the ham radio
> fraternity, I can say that we're a frugal bunch (read: cheap!)
> Recently, at a ham radio swapfest, I picked up a commercial ham radio
> repeater. It's a Motorola R-100. What a repeater does (for those who
> don't know) is it receives a signal on one frequency, then (usually from
> a high vantage point because V/UHF propagation is 'line-of-sight')
> "repeats" it on another frequency. Call it a 'range extender', if you
> like. Placement on building roof-tops, or tall towers is common. This
> allows, for example, someone in their car on the East side of town to
> talk (via the repeater) to someone in their car on the West side of
> town, when the distance is too great for these to mobile units to talk
> directly to each other.
> Eventually, once the repeater is programmed and installed at a tower
> site, it will then be accompanied by a Micro-ITX computer (small
> footprint) a 4gig solid state drive, run headless, and incorporate VoIP,
> via Internet Repeater Linking Project to connect to other repeaters all
> over the world. Interesting note about the IRLP is, it uses Linux, and
> they've adopted CentOS as their host OS. (another Plus for the
> Penguin!). For more info on IRLP see http://irlp.net
> These old radios show up on the used market all the time, typically from
> commercial radio installs that have been upgraded or are obsolete. This
> particular radio is currently programmed on the commercial two-way
> frequencies, is from the mid/late 80's and is computer programmable. The
> hex editing was to change the band-split of the radio to allow it to
> cover the Ham frequencies.
> Sounds like a simple process, right? Hook up the radio via a cable to
> the computer, invoke the program, punch in the new frequencies, save it
> and be done... right? Oh, no. Indeed NOT! It seems the geniuses at
> Motorola wrote the software specific to CPU clock cycles. Which means
> -old- hardware is needed to program the radio, and -maybe- a computer as
> fast as a 486-SX 33, running DOS 5.0 machine 'might' be slow enough for it.
> Turns out, I found my old laptop back in San Antonio (the aforementioned
> 486-SX-33) in the form of an IBM Thinkpad 355C. I'm sure this thing was
> the bottom of the line, but some enterprising hacker had managed to load
> Windows95 on it. I have vague memories of this machine being -way-
> underpowered for Win95, and was -forever- waiting on it to do
> -anything-. But, it has a PCMCIA slot, a 56k PCMCIA modem (long ago
> lost) and all that was needed was a phone jack. Remember those days? ;-)
> Assuming the floppy drive is still good, and while I -have- found the
> power supply for the laptop, getting the file that I've now hex-edited
> (thanks to {{shuder}} vi {{shudder}}) from my openSuSE 11.2 Linux
> machine on a dual-core Dell PowerEdge SC430 (with NO floppy) to the
> Thinkpad is going to be a chore. I'm pretty sure the Thinkpad 355c was
> pre-usb days.
> Linux has come to the rescue in many other ways on this project... what
> would you suggest to transfer the file from a semi-state-of-the-art
> system to an ancient dinosaur of a system?
> -Geoff

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