HDT-ROM HDT meens HEX-DEC-TEXT and relates to the built in new monitor. This ROM for the ZX Spectrum is based on the ISO-ROM but with significant more comfort in the HDT against the ISO-ROM. Directly taken from the ISO-ROM is the BASIC-Line-Editor, the eliminated (in the original ROM) errors and the PAUSE without number command. The double speed routine (2,6k Baud) halves all clock cycles. Therefore it is possible, to load all old files in the half of the time if you switch the recorder to the double speed. But the double baudrate is also with the normal speed very reliable what is proved in practice. The build in monitor can be invoked over NMI or in BASIC by typing * at the command line. The following options are available in the monitor: 1 - switch between HEX/DEC (display and input) 2 - switch between byte/text display of the memory content 3 - load the flashing stack or register 4 - load the top memory cell 5 - memory display -64 6 - memory display -1 7 - memory display +1 8 - memory display +64 9 - stack and register choice -1 0 - stack and register choice +1 symbol shift and 7 - the entered address will be processed as assembler CALL. At the end (1. RET) the program returnes to the monitor. Register contents are not considered! symbol shift and 8 - makes a relative safe jump to the BASIC editor (#1303) symbol shift and 9 - executes a RST 8 (error output) and after that to the editor symbol shift and 0 - executes a RET, continues at the point where the actual program was interrupted by a NMI pulse (if the pulse was short enough). The address to continue is displayed at the top of the stack column. SPACE - enter a byte in the actual memory cell RESET - warm start CAPS and RESET - cold start The BASIC improvements are: The cursor keys (6 and 7) can also used by editing in the line. #nnnn - edit line with number nnnn + - switch to higher baud rate - - switch to lower baud rate ) - switch off the display of the three 2-byte numbers in the header ( - switch on the display of the three 2-byte numbers in the header * - call the build in monitor from basic , - display the free memory for about 5 seconds Quelle: http://www.zxspectrum.it/