Modem Digitelec DTL 2000

[Dbug]

The DTL 2000 was a V23 modem available for the Apple II, Amstrad CPC and Oric (possibly other machine as well).

I found an Apple II version of the manual thanks to rijiji on the CEO forum.

I'm wondering if anyone has some actual documentation and/or the original software for it.

There is some technical data about this modem in Theoric #4 on pages 32 to 35.

So apparently it uses the page 3 registers 3F8 and 3F9 to access a PIA 6821, and registers 3FC and 3FD to access the ACIA 6850A.

Could "Oricon" (or some other terminal program) work with this device and allow for example connecting to a BBS or a minitel server?

[iss]

There is very good chance to make DTL 2000 work!
It uses the same ACIA as Oricon - MC6580. The difference with the other famous ACIA 6551 is that it doesn't have own baud generator.
Attached is the OTRM 2.0 (my updated Oric terminal program) compiled for MC6580 at #3FC as base address.

20250313_120535.jpg (11.61 KiB) Viewed 970 times

The internal clock divider is set to /16.
I think you need only to POKE the needed values to configure the PIA 6821 (at #3F8/3F9).
Be careful there are many typos in the first picture in your post.
IMHO this are the correct POKE's for 1200/1200 mode:

Code: Select all

10 POKE #3F9,#00
20 POKE #3F8,#F4
30 POKE #3F9,#04
40 POKE #3F8,#C4

Then simply start OTRM and it should work.

[Dbug]

Guess If I want to talk to a minitel, I should probably have either 75/1200 or 1200/75.
I'll try the program later

Thanks!

[iss]

Guess If I want to talk to a minitel, I should probably have either 75/1200 or 1200/75.

I think so too.
Currently OTRM uses IRQ to receive data but I don't know if DTL-2000 provides it, we can change easily to polling if it doesn't.

[Dbug]

I had to change the fuses to get any reaction from the device, fortunately I had a box of glass 1A fuses.

After that I was able to get the thing to react: On boot all the LEDs are off except the one on the right labelled "MARCHE" (ON), and after doing a couple of pokes I got the "TEST" LED to appear.

To try OTRM I need to solve the problem of connecting the modem and either Loci or Erebus, because I'm doing going to do CLOAD from tape or mp3 player to do tests, that's going to take some time so I'm postponing that to the weekend

[kenneth]

#3F8 #3F9 #3FC #3FD adresses are used for the modem. Maybe there is no conflict with the Erebus device using #3F3 location.

[Sodiumlightbaby]

You should be good with LOCI as well.
#310-31B DSK/TAP/ULA etc
#380-383 ACIA (for now)
#3A0-3BF LOCI API

LOCI uses open collector drivers (only pull-down) for IRQ, RESET, ROMDIS, MAP and IO_CONTROL so should also play well with shared bus devices.

[Dbug]

So I guess all I need is to make a cable splitter with two connectors, or add a female IDC connector on the modem cable and connect either Loci or Erebus on it.

[kenneth]

For the Erebus device, a diode must be added on the pcb to "share" the peripherals.
It is shown as below:
https://ceo.oric.org/community/peripher ... ur-oric-1/

[Dbug]

For the Erebus device, a diode must be added on the pcb to "share" the peripherals.
It is shown as below:
https://ceo.oric.org/community/peripher ... ur-oric-1/

Ok, so like that:

[kenneth]

indeed

[Dbug]

So I added the diode, and I also added a connector on the modem cable and I can confirm that both Erebus and Loci run just fine with the modem in this configuration.

Doing the earlier pokes I can still get the TEST LED to switch ON so the modem is happy as well, so that's good new.

When I run OTRM I'm getting the blue message, but then after that all I get is a black screen.

I'll let the modem exploration rest for a while, there are a few things I need to do on the side (among other, fix the damn keyboard of my minitel that stopped working), and I'll revisit that later when I have more time (After the big work project release end of May)

[Chema]

This is really interesting!! Keep us updated!