If you don't close ModelSim, you will get an error when you rerun it. ModelSim can only be compiled for one project at a time.

As for simple methods, there are:

1. After running Modelsim for the first time, click the "Up" key on the serial port of Modelsim's transcript, and the command do XXXXX.do will appear. This is the command to run ModelSim, and it is not used for the time being. You change to edit XXXXX.do, click Enter, and a window will pop up. You can add a # sign in front of the following contents in the window to prevent the library from compiling again and save time. When finished, click Save to close this window.

vlib verilog_libs/altera_ver

Vmap changes version. /verilog_libs/altera_ver

vlog-vlog 0 1 compat-work altera _ ver { d:/altera/ 1 1.0/Quartus/EDA/sim _ lib/altera _ primitives . v }

vlib verilog_libs/lpm_ver

vmap lpm_ver。 /verilog_libs/lpm_ver

vlog-vlog 0 1 compat-work LPM _ ver { d:/altera/ 1 1.0/Quartus/EDA/sim _ lib/220 model . v }

vlib verilog_libs/sgate_ver

vmap sgate_ver。 /verilog_libs/sgate_ver

vlog-vlog 0 1 compat-work sgate _ ver { d:/altera/ 1 1.0/Quartus/EDA/sim _ lib/sgate . v }

vlib verilog_libs/altera_mf_ver

vmap altera_mf_ver。 /verilog_libs/altera_mf_ver

vlog-vlog 0 1 compat-work altera _ MF _ ver { d:/altera/ 1 1.0/Quartus/EDA/sim _ lib/altera _ MF . v }

vlib verilog _ libs/altera _ LNS im _ ver

vmap altera_lnsim_ver。 /verilog_libs/altera_lnsim_ver

vlog-SV-work altera _ LNS im _ ver { d:/altera/ 1 1.0/Quartus/EDA/sim _ lib/altera _ LNS im . SV }

vlib verilog _ libs/cyclone ive _ ver

vmap cycloneive _ ver。 /verilog _ libs/cyclone live _ ver

vlog-vlog 0 1 compat-work cyclone ive _ ver { d:/altera/ 1 1.0/Quartus/EDA/sim _ lib/cyclone ive _ atoms . v }

2. You can modify your logic code in Quartus, and then press the "Up" key directly in the serial port of Modelsim's codebase to find out the do XXXXX.do command just now, and then enter the car to run. At this time, Modelsim will simulate according to your modified program, but please note that if the ports and variables of the main program change, you need to modify your testbench file, otherwise you will report an error.

This is just a simple compilation. If you don't understand, keep asking. If not, please adopt ~