NIBL 1200 GT - faster BASIC

1-50 — elektor January 1982 NIBL 1200 G1 W. Taphoorn The NIBL interpreter is one of the few that do not utilise a UART for the serial transfer of data into and out of the computer. Instead, the data is trans- mitted and received in serial form directly by the microprocessor. For this purpose, flag 0 is used as the output and sense B is used as the input. Conversion from serial data to parallel data, and vice versa, is accomplished with the aid of two subroutines contained in the interpreter program. For these reasons, together with the fact that NIBL is (normally) held in ROM, it is very difficult — if not impossible — for the operator to alter the speed of trans- mission. However, it can be done! NIBL operates as follows: During transmission a start bit is added to the data word to be transmitted. The term "start bit" rightly implies that this bit is transmitted first (via flag 0), the bits in the data word will follow. Finally, two stop bits complete the procedure. Transmi...