Connect Minitel1B to Ubuntu 20.04

I'm trying to use a Minitel as a console to connect to my Ubuntu. I've read a lot of information about this, but it seems to work with older versions of Ubuntu. These two files : - etc/inittab - etc/gettydefs ... don't do the job for me ! My inittab: 1:2345:respawn:/sbin/agetty ttyUSB0 4800v23 My gettydefs : 4800v23# B4800 CS7 PARENB -PARODD GLOBAL # B4800 ISTRIP CS7 PARENB -PARODD GLOBAL BRKINT IGNPAR ICRNL IXON IXANY OPOST ONLCR CREAD HUPCLISIG ICANON ECHO ECHOE ECHOK #@S login: #4800v23 The result of "sudo lsusb -v" : Bus 003 Device 002: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 8 idVendor 0x1a86 QinHeng Electronics idProduct 0x7523 HL-340 USB-Serial adapter bcdDevice 2.64 iManufacturer 0 iProduct 2 USB Serial iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 0x0027 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 98mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 3 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 1 bInterfaceProtocol 2 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0020 1x 32 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x02 EP 2 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0020 1x 32 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0008 1x 8 bytes bInterval 1 can't get debug descriptor: Resource temporarily unavailable Device Status: 0x0000 (Bus Powered) Today I can do this : sudo stty -F /dev/ttyUSB0 4800 parenb cs7 hupcl cread ignpar clocal ixon ixoff opost onlcr isig echoe echok echoctl echoke and this : echo "Hello Minitel" > /dev/ttyUSB0 ... prints Hello Minitel on my Minitel screen. But I'm not able to have a prompt on my minitel. Thanks for your help, and sorry for my "poor english" (I'm an old french developer ;)