Com-WiFi modem for old computers
How to access the Internet on a forty-year-old DOS machine with 640Kb of RAM and a 9-megahertz processor?
Of the communication ports in old computers, there is usually COM, also known as “serial”, and we will connect it to this small box, which does all the magic:
Creator of the device, author of the resource theoldnet.com it's like a time machine for old computers – you can see what some Yahoo looked like in 1996. The modem is inexpensive and is sold here – I recommend it to everyone who doesn’t want to bother with firmware and wires. For those who are not afraid of this, I will tell you in general terms how to assemble an analogue:
You will need a WiFi Board NodeMCU V3 ESP8266 and an RS232 (DB-9) TTL adapter based on the MAX3232 chip (or equivalent). If you're not too lazy, you can solder all the parts on the breadboard, but for me it was easy to stick jumpers. The connection diagram is simple – RX-RX, TX-TX, GND-GND, VCC (power supply) of the RS232 adapter is connected to the Vin pin on the MCU (5V). That's it – the hardware is ready. I happened to have a modem cable on hand, but you can probably plug it directly into the com port.
Modem emulation mode
The thing works in two modes – modem emulation and SLIP Serial Line Internet Protocol. Let's look at the first mode. The firmware and initial setup are shown in great detail in this video:
Project author page theoldnet on gitdownload the firmware here – take the firmware theoldnet_serial_wifi_ppp
Actually, “barusing” goes through console utility MS-DOS Kermit which is so cool that it deserves its own post. Yes, yes, these are the same BBS that you heard about from oldfags. After some dancing with a tambourine, enter the ATDT command, open bbs.restrocampus.com and enjoy the result:
SLIP emulation mode
BBS is certainly interesting, but if we need FTP, Ping and even a graphical browser, then we need to configure Ethernet via the com port (we sew the device with theoldnet_serial_wifi_ethernet firmware from the same archive). Detailed text instructions here. Video instructions from Theoldnet itself:
In short, the package does all the magic. mTCP for DOS from Michael Brutman – just a brilliant thing, big respect to the guy. In short, the ethersl.com driver (it and other mTCP utilities are in the theoldnet archive with firmware) raises a “virtual” network adapter that mTCP utilities can access. The client machine has the address 192.168.240.2 registered with the Node MCU – 192.168.240.1, then the MCU itself connects via WiFi to your router and receives an address via DHCP, such as double NAT. Setting up SSID and Password is done through the console, video from our friend here.
I'll wrap it up here, the article is already long! I would be glad if the information inspires someone to do new experiments with old computers and someone might discover this topic for themselves for the first time!
Peace and goodness to everyone
