Keil IDE does support the SP370, but not through an entry in the device dropdown menu.
Instead, you should select "Intel 8052AH" as the CPU type.
Furthermore, you should specify "Off-chip code memory" starting at 0x4000 with a length of 0x1800 bytes.
Instead, you should select "Intel 8052AH" as the CPU type.
Furthermore, you should specify "Off-chip code memory" starting at 0x4000 with a length of 0x1800 bytes.