The need for an improved cassette interface was apparent from the number of complaints received from ZX81 users, who encountered problems when trying to save and load programs. To increase the data transfer speed, the team significantly decreased the length of tones that represent binary data. To increase the reliability, a leading period of constant tone was introduced, which allowed the cassette recorder's automatic gain control to settle itself down, eliminating hisses on the tape. A Schmitt trigger was added inside the ULA to reduce noise of the received signal. Originally, the team aimed for data transfer speed of 1000 baud, but succeeded in getting it to work at a considerably faster 1500 baud. Unlike the ZX81, the Spectrum was able to maintain its display during loading and saving operations, and programmers took advantage of this to show a splash screen whilst loading took place in the background.
The need for an .improved cassette interface was apparent from the number of complaints received from ZX81 users, who encountered problems when trying to save and load programs To increase the data transfer speed, the team significantly decreased the length of tones that represent binary data. To increase the reliability, a leading period of constant tone was introduced which allowed the cassette recorder's automatic gain control to settle itself down, eliminating hisses on the tape. A Schmitt trigger was added inside the ULA to reduce noise of the received signal. Originally, the team aimed for data transfer speed of 1000 baud but succeeded in getti,ng it to work at a considerably faster 1500 baud. Unlike the ZX81, the Spectrum was able to maintain its display during loading and saving operations, and programmers took advantage of this to show a splash screen whi,lst loading took place in the background.