phooky is a user on You can follow them or interact with them if you have an account anywhere in the fediverse. If you don't, you can sign up here.
phooky @phooky

thanks for everyone who contributed to this moment of mirroring a 4MB flash volume over a 9600b serial cable to interlink running on dosbox

· Tusky · 10 · 25

The key was finding a line in the flash filesystem's autoexec that dropped into maintenance mode if it finds a certain file on the ramdisk. However, the flash is read-only. So how do we get the file to the ramdisk after a reboot? And there's the fun twist-- as long as power is maintained, the ramdisk *persists across reboots*! Not at all what we'd expect from a modern system but completely sensible for the time. So touch the file, reboot, and there we go.

@er1n @phooky I'm curious too, although looking closer at the keypad and what appears to be a repurposed PC PSU being used to supply it with DC voltage I'm guessing at it possibly being a mobile data terminal recovered out of a van/trunk (could be either civillian or public service agency) that would have sent data over VHF/UHF radio frequencies..

@vfrmedia @er1n it's actually getting 12V from my bench supply; the giant PSU you see is being used to prop it up so I could get at the DB9 serial connectors underneath. :)

@er1n it's an MDT-9100T, a mobile terminal meant for installation in cars; I've removed the radio component.

@phooky @er1n I've seen modern versions of this used by London Ambulance Service (until they moved to Airwave/Tetra digital comms in the late 2000s) although prior to that the blue light services where I then lived (Reading, about 60km West of London) all still used analogue voice comms.

Interesting to learn the Dutch Police used it (and with better encryption than the USA agencies had!)

@vfrmedia @er1n yes! I was hoping mine (an ebay find) would come with the crazy Phillips crypto pcmcia card, but no such luck.

@phooky @er1n those crytpo cards are probably all probably all still locked away somewhere at AIVD Zoetemeer (NL security service)... I got the impression crypto wasn't widely used outside NL and it would have cost a lot too (Philips most likely got govt subsidies to build the system as they still had a lot more presence in NL back then)

@vfrmedia @phooky @er1n i just can't stop staring at that 'form esc FORMS-Ctrl' key

@bunnyhero @phooky @er1n would have made sense for such things as info about a patient, an incident report etc (no GUI so screens of forms would be filled in on the MDT and when it was complete "send" (possibly the # on the telephone style keypad) pressed to key the radio and transmit the data (usually as FSK). ISTR hearing this kind of data mixed in with voice when scanning on VHF low band in late 90s UK (think it was vehicle recovery services such AA/RAC).