DDCMP sync?

[Mattis Lind]

I did a thing called SyncDongle.(
https://github.com/MattisLind/alfaskop_emu/tree/master/hardware/SyncDongle)

Essentially a BluePill with some level converters. It is using the SPI port
for sync communication.

Then I developed a BSC implementation and a HDLC implementation to use on
the SyncDongle.

https://github.com/MattisLind/alfaskop_emu/tree/master/Utils/BSCGateway/BSCBridge

https://github.com/MattisLind/alfaskop_emu/tree/master/Utils/SDLCBridge

BSCBridge is more finished and works quite well to communicate between a
USB host (Hercules) and a BSC terminal controller.  SDLCbridge is working
but is unfinished but tested fine with some simple SDLC messages to a
terminal so the low level stuff seemed to work.

https://youtu.be/H1Sxt7xjn4Y
https://youtu.be/CFfB3yCN9OI

Not sure if 1 mbit/s is possible with the SyncDongle hardware. But it might
be.

/Mattis



Den tis 26 jan. 2021 kl 02:46 skrev Paul Koning via cctalk <
cctalk at classiccmp.org>:

> In playing with DECnet I built a DDCMP implementation which deals with a
> byte stream, normally from a UART.  So that works nicely with async link
> DDCMP as found in RSX and several other operating systems.  But the speed
> is limited.
>
> The other option would be synchronous links, which would enable
> connections to DMC11 or the like at speeds up to 1 Mb/s.  But synchronous
> comm devices that connect to modern computers aren't so easy to find,
> though I have seen a few.
>
> After playing with Arduino for LK201 keyboard emulation I started to
> wonder if one could be made to be a synchronous comm link with a USB back
> end, with low level things like byte framing and maybe DDCMP packet format
> handling in there, but the protocol state machine in the host behind the
> USB interface.  For moderate speeds that seems entirely practical.  For 1
> Mb/s, probably not, though perhaps one of the fast ARM based units with its
> built-in SPI could be warped into that.
>
> The alternative would be something like a BeagleBone Black (or Green) such
> as David Gesswein used as the engine for his MFM hard disk emulator.  That
> clearly could do the job without any strain.
>
> So I'm wondering: would there be interest in such a thing?  If yes, should
> it be a modem-connected one (RS232 signaling, bit clock supplied externally
> by a modem or modem-eliminator)?  Or should it be the "integral modem"
> short distance type, the ones that used a pair of coax with 4-pin AMP
> connectors like this
> https://www.digikey.com/en/products/detail/te-connectivity-amp-connectors/206060-1/15588
> ?
>
>         paul
>
>