Jump to content

Photo

SDLEP-Reader - Tapes are getting emulated too

tape cassette emulation

1 reply to this topic

#1 CatPix OFFLINE  

CatPix

    River Patroller

  • 3,575 posts
  • Location:France

Posted Fri Jan 6, 2017 8:49 AM

I'm not sure if it's a new thing or not, but I would believe it is - tapes on 90% of our 8 bits systems are simple audio tapes, and "emulation" can be done by simply wiring the cassette interface with any sound source able to read audio files.

 

Still, some computers can be tricky. At least the Thomson computers used a specific tape reader that converted the audio data into digital data - it mean that the input expect a TTL signal, and therefore the standard audio signal is too weak for the computer (TTL signals use 5 volts).

 

Daniel Coulom, fan of Thomson computers, decided it was time to solve this issue. Most of the programs for the iconic (In France) MO5 and TO7-70 computers came on tape. Only a very few were on floppies, and no more than 5 or 6 programs came on cartridges, most of theim being BASIC and other languages.

He created an extention that allow to read a SD card from the joystick controllers (!) - as useful as it is, most cassettes games need to be converted, and some games doesn't like to be converted to a floppy format, mostly the ones with copy protection (yep, it exist...).

So he went back to his drawing board and came up with the SDLEP-Reader :

 

http://dcmoto.free.f...ader/index.html

 

sdlep-reader_05.jpg

 

It is simply based on an Arduino, that read files from a SD card.

 

Now, since TTL signals are square signals, and that it's what is needed in the audio format of most computers, it is pretty easy to add a resistor to drop the 5V from the TTL signals to levels acceptable by most computers :

 

sdlep-reader-cables_20170106.png

 

The SDLEP-Reader can be powered by 5V or 12V sources, usually from the computer as most have a power source for peripherals, but can be done with a power supply if needed.

 

sdlep-reader_00.jpg

 

The files can be converted from wav to .lep, a file format created specifically to emulate the tape in a compact form (there is a similar format (in mind, not sure about the way it works) for ZX Spectrum) :

http://dcmoto.free.f...teur/index.html(scroll down to DCLEP).

 

As the SDLEP-Reader emulate the tape player, loading from the SDLEP-Reader is going to take minutes. Some long tapes might get a shortened loading time if the tape was recorded with a slower bitrate, but you won't have SD2IEC result and load a tape game at the speed of a cart game.

 

Also, as the name implies, the SDLEP-Reader doesn't include a record function. Daniel though that no one today would write programs on a real machine an record it on tape so be ignored that function.

 

Note that the project is not open source - Daniel wish that no commercial use of his products is made - but you're free to do it yourself, to modify what he did, etc.

Also, this project was published very recently, so, the module is tested and confirmed to work on Thomson computers (TTL signal) and on the Philips VG5000 (standard audio input) it hasn't been tested yet on other systems.

Feedback for other computers should arrive when Daniel will receive new parts and send modules to some members of the system-CFG forums, but nothing stops you to make your own SDLEP-Reader and try it on any machine you want.



#2 Carl from System-cfg OFFLINE  

Carl from System-cfg

    Combat Commando

  • 1 posts

Posted Tue Jun 13, 2017 3:16 PM

Hi !

 

Currently, SDLEP have been tested on following computers :

 

- Thomson MO5, MO6, TO7/70, TO8
- Philips VG5000, VG8000, VG8010, VG8020
- Matra MC10, Alice, Alice 32, Alice 90
- Exelvision EXL100
- Amstrad 464, 6128
- Sinclair Spectrum 48K, 128K, +2A, +3
- Oric 1, Oric Atmos
- Vic20, C64, C128
- Acorn Electron

 

you can dowload some tapes files here : 

https://forum.system....php?f=6&t=8064

 

regards,

Carl







Also tagged with one or more of these keywords: tape, cassette, emulation

0 user(s) are browsing this forum

0 members, 0 guests, 0 anonymous users