'Example of using the word functions that are in the 'WORD.BAS file to manipulate the I/O ports. ' 'By: George Spafford Copyright 1993 ' 'No additional libraries required ' 'v1.0 05/02/93 ' '************************************************** 'If you use these routines, please have the courtesy 'of registering the tutorial. 'Make sure that you have all of your variables typed 'correctly before you use one of the following 'routines. Use integers where integers are identified (%). 'Use long integers where long integers are identified (&). 'Int2Long& is a function that accepts a signed 'integer and returns an unsigned long integer. Since 'BASIC uses the high bit to toggle the sign of an 'integer, you must convert it to a long integer before 'you perform any bit operations on it. DECLARE FUNCTION Int2Long& (IntNumber%) 'BASIC does NOT have a built in facility to PEEK 'words! Tell the PeekWord% function where to look, 'and it will read in a word at that segment and offset. DECLARE FUNCTION PeekWord% (Segment%, Offset%) 'As with Peeks, BASIC does not support a POKE function 'for words. This next subroutine adds that capability. 'Tell the subroutine the segment, offset and word that 'you wish it to POKE in and it will do so. DECLARE SUB PokeWord (Segment%, Offset%, Word%) 'As you code more and more programs, try to make your code 'as modular as possible. By creating objects (OOP systems), 'you can significantly increase your code reusability. 'Try to only create the wheel once! Some of the demos would 'benefit greatly by judicial use of subroutines. In order to 'have top-down readability, I did not modularize the code. 'Just a FYI -- George DEFINT A-Z Title$ = "S3 Demo of WORD functions and I/O ports Copyright George Spafford 1993" Main: CLS PRINT Title$ LOCATE 3, 30: PRINT "To enter hexadecimal numbers, prefix your answer" LOCATE 4, 30: PRINT "with &H. For example, &H400 represents 400 Hex." LOCATE 3, 1 GOSUB ReadPorts PRINT "Menu Port Address" PRINT "---- ---- -------" PRINT " 1. COM1: "; HEX$(COM1); " Hex" 'HEX$ formats numeric PRINT " 2. COM2: "; HEX$(COM2) 'input to a hexadecimal PRINT " 3. COM3: "; HEX$(COM3) 'string representation PRINT " 4. COM4: "; HEX$(COM4) PRINT " 5. LPT1: "; HEX$(LPT1) PRINT " 6. LPT2: "; HEX$(LPT2) PRINT " 7. LPT3: "; HEX$(LPT3) PRINT " 8. LPT4: "; HEX$(LPT4) PRINT "=======================" PRINT PRINT "Please select an option:" PRINT INPUT "(D)elete (E)dit (S)wap (Q)uit: ", Ans$ Ans$ = LTRIM$(RTRIM$(UCASE$(Ans$))) 'trim spaces and make the 'answer upper case. IF Ans$ = "" THEN PRINT : PRINT : END 'if answer is NULL then end 'Just a note regarding efficiency when conditions are involved: 'If you have more than a couple of repetitive tasks to test, use 'the SELECT CASE method. IF THEN statements require converting and 'testing a condition each time. A select only has to convert the test 'variable once and then evaluate it against all of the answers. 'Taking this approach one step further, if you can use integer varaibles, 'then the test is even faster. In the instance below, speed is not a 'factor, readability is. SELECT CASE Ans$ CASE "D" PRINT INPUT "Delete which port: ", Del$ Del$ = LTRIM$(RTRIM$(Del$)) IF Del$ <> "" THEN Value = VAL(Del$) GOSUB Choice IF Offset <> 0 THEN CALL PokeWord(0, Offset, 0) END IF END IF CASE "E" PRINT INPUT "Edit which port: ", Edit$ Edit$ = LTRIM$(RTRIM$(Edit$)) IF Edit$ <> "" THEN PRINT Value = VAL(Edit$) GOSUB Choice IF Offset <> 0 THEN INPUT "New value: ", NewValue CALL PokeWord(0, Offset, NewValue) END IF END IF CASE "S" PRINT INPUT "Swap port one: ", From$ Value = VAL(From$) GOSUB Choice FromAddr = Addr FromOffset = Offset INPUT "Swap port two: ", To$ Value = VAL(To$) GOSUB Choice ToAddr = Addr ToOffset = Offset IF ToOffset <> 0 AND FromOffset <> 0 THEN CALL PokeWord(0, ToOffset, FromAddr) CALL PokeWord(0, FromOffset, ToAddr) END IF CASE "Q" PRINT : PRINT : END END SELECT GOTO Main END Choice: Addr = 0 SELECT CASE Value CASE 1 Addr = COM1 Offset = COM1off CASE 2 Addr = COM2 Offset = COM2off CASE 3 Addr = COM3 Offset = COM3off CASE 4 Addr = COM4 Offset = COM4off CASE 5 Addr = LPT1 Offset = LPT1off CASE 6 Addr = LPT2 Offset = LPT2off CASE 7 Addr = LPT3 Offset = LPT3off CASE 8 Addr = LPT4 Offset = LPT4off CASE ELSE Addr = 0 Offset = 0 END SELECT ReadPorts: 'The BIOS data area starts at 0000:0400. The first '16 bytes of it concerns the I/O ports. If the port 'is enabled, there will be a word entry that describes 'the I/O address where data should be sent when that device 'is used. If the word is 0, then the device has not been 'recognized. If a value is forced, then the system will 'recognize that port whether it truly exists or not. 'For example, some systems do not automatically scan 'for COM3 and COM4 at POST (Power On Self-Test) time. You 'must enter the address manually for that port if you 'need to use it in those instances. COM1off = &H400 'Save Offset COM1 = PeekWord%(0, COM1off) 'Get I/O address used COM2off = &H402 COM2 = PeekWord%(0, COM2off) COM3off = &H404 COM3 = PeekWord%(0, COM3off) COM4off = &H406 COM4 = PeekWord%(0, COM4off) LPT1off = &H408 LPT1 = PeekWord%(0, LPT1off) LPT2off = &H40A LPT2 = PeekWord%(0, LPT2off) LPT3off = &H40C LPT3 = PeekWord%(0, LPT3off) LPT4off = &H40E LPT4 = PeekWord%(0, LPT4off) RETURN DEFSNG A-Z FUNCTION Int2Long& (IntNumber%) 'If the integer is negative, we need to add 65536 'to the number (which is 2 * integer limit) to get 'our new long integer. IF IntNumber% < 0 THEN Int2Long& = 65536 + IntNumber% ELSE Int2Long& = IntNumber% END IF END FUNCTION FUNCTION PeekWord% (Segment%, Offset%) DEF SEG = Segment% 'set segment High = PEEK(Offset% + 1) 'High byte is at offset + 1 Low = PEEK(Offset%) 'Low byte is at offset PeekWord% = (High * 256) + Low 'Compute the word value DEF SEG 'return to default segment END FUNCTION SUB PokeWord (Segment%, Offset%, Word%) DEF SEG = Segment% 'Set segment High = (Word% \ 256) 'perform integer division 'to compute the high byte Low = Word% - (High * 256) 'compute the low byte POKE (Offset% + 1), High 'POKE in the high byte POKE Offset%, Low 'POKE in the low byte DEF SEG 'return to the default segment END SUB