Archivi categoria: Coding

SWAG at markreds.it

Pascal is an imperative e procedural high level programming language. I learnt it at high school and developed applications with Borland Delphi for many years in my first employment.

The Macintosh System OS (the classic one) was developed in Pascal and Apple released its official documentation keeping this language as main reference to developers that wanted to develop for its platform.

Fews days ago I’ve found an interesting site about Pascal programming with lots of examples called SWAG (Sourceware Archive Group).

SWAG is a collection of source code and program examples for the PASCAL programming language. The material has been donated by various PASCAL programmers from around the world, who desire to contribute to the advancement of one of the greatest programming languages there is. SWAG packets are available in 57 different categories covering EVERY aspect of the PASCAL language, and ALL ABSOLUTELY FREE !!! … The material contained in SWAG is intended to be a teaching and learning aid for users of the PASCAL language. Whether you are a beginner or experienced programmer, you’ll find SWAG to be an invaluable source of ideas and information.

So I’ve decided to keep a copy of the last SWAG release. Click here to start reading.

Teleport Gold modem reconversion

A few years ago I bought a Global Village Teleport Gold II fax/modem for my personal vintage collection. I had been always fascinated from old stuff used to communicate in the world wide web of that era but today they are almost useless except as an ornament accessory for my Macintosh Classic.

I don’t why but these days I started thinking when I was younger and I was moving my first steps into the Internet. No many years ago, really, but there weren’t broadband connections, wifi and social networks. To navigate I had to plug my serial modem to the telephone outlet, dialing to my internet provider and start the PPP session, wait for the complete loading of every web page keeping an eye to the minutes counter or my father would have scolded me! Now everything is changed, we are always connected, social networks are became the usual way to communicate each other. So that old serial modems are became useless, even for fax messages (who’s still use them?).

So I got this idea: why don’t try to reconvert my Teleport Gold modem to allow at least a wifi connection to my Macintosh? I had already known the amazing Bo Zimmerman’s Zimodem project buying an adapter for my Commodore C64 and I’d liked to get something similar for my Classic also.

The first goal was to keep the aesthetic of the original modem. In addition I wanted to use the Macintosh modem port. So I started to search informations about the RS-422 interface and how it could be connected to the UART of a ESP32 MCU. I discovered that the RS-422 is very similar to the more standard RS-232 and that I could use a MAX3232 IC as signal converter.

Top view of the modem board I built. I’ve used and ESP32 MCU controller. Near the DB9 connector you can see the TTL<-> RS-232 converter. I use the same IC for both DB9 (RS-232) and Mini DIN 8 (RS-422) connectors.

At this point I built the circuitry needed for my project. I pulled up from the original logic board the serial cable, switch and power plug . I replaced the telephone plugs with a DB9 connector in case I would use this modem with my Amiga. Since Zimodem firmware supports an SD card on ESP32, I put it one. I added also an internal speaker in case I want to simulate the old dial-up sound (do you remember that Pshhhkkkkk krrrrka kingkakingkakingtsh chchchchchchchcch dingdingding ?) or if I’d wanted to add some extra features.

Then I got a copy of the Zimodem firmware and I added some changes to drive the LEDs on the front panel of the Teleport Gold modem: one green led for the power on, another green one when the wifi connection is active and a yellow led for the serial activity.

After flashed an ESP32 and made the final checks (I didn’t want to blow my Classic, of course) I started the Terminal program – no, it’s not the Mac OS X one 😛 – and input some AT commands.

Here following some picture of my work. Any feedback is appreciated.

LED Library

Comincio a prenderci gusto… ecco un’altra libreria per comandare un led su Arduino. La mia versione permette di far lampeggiare un led oppure di accenderlo e spegnerlo lentamente con un effetto respiro in modalità non bloccante.

Trovate sorgenti ed esempi sul mio GitHub. Commenti e contributi sono ben accetti!