The following are a sample of some of the subroutines I've gleaned from the NEC ROM. Suggestions for improvement of the format are welcome. I'll try to clear up any ambiguities that have crept into my notes. It would certainly be interesting to get all the NECy owners on this SIG to contribute similar material. Please note that, to be useful, contributions should use roughly the same format and supply the same information. For the record, none of the information published here was obtained from "classified" NECHE sources. I don't get a chance to log on to CIS much, so messages may scroll off before I see them. It's best to either leave me E-mail or drop a note via MCI mail (my MCI account number is 114-5685). Cordially, Alex Lane 75715,1370 TITLE: RST 5 ENTRANCE: 1338H (4920) INCOMING REGISTERS: none REGISTERS AFFECTED: A REMARKS: This subroutine is called when the RST5 instruction is executed. Contents of FA8BH (64139) are loaded into A, the number 11 is subtracted, and the routine returns. Note that all condition flags except CY may be affected. Alex Lane 75715,1370 TITLE: Lower-to-upper case ENTRANCE: 12B6H (4790) INCOMING REGISTERS: HL REGISTERS AFFECTED: A REMARKS: HL contains the ASCII value of the letter to be tested. Accumulator is loaded with HL contents. If the value in the accumulator is outside the limits of ASCII lower-case letters, the routine returns; otherwise, the accumulator contents are changed to upper-case, and the routine returns. Alex Lane 75715,1370 TITLE: RST 3 ENTRANCE: 0018H (24) INCOMING REGISETRS: HL, DE REGISTERS AFFECTED: A REMARKS: This subroutine is called when the RST3 instruction is executed. The HL and DE register pairs are compared, and the zero and carry flags are set as shown in the following table: | HL = DE | HL > DE | HL < DE | --+-----------+-----------+-----------+ Z | 1 | 0 | 0 | --+-----------+-----------+-----------+ C | 0 | 0 | 1 | --+-----------+-----------+-----------+ Alex Lane 75715,1370