The function READ returns the F-Code response, if any, from the LV-ROM player. VFS provides a further OSWORD call, &64, which obtains this response from the player. This works in a slightly different way to serial communications. In serial communications mode, all responses from the LV-ROM player are received by the BBC into the RS423 input buffer, and they remain there until the input buffer is read or cleared.
Reading the F-code response via OSWORD &64 only returns the most recent response. If the F-code has not been read and another response is sent by the player, then the earlier response is lost.
The function FCODE joins the two parts together, transmitting an F-code to the player and then reading the response with a single function call.
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