'   Advanced Communication Board Developer Toolkit
'   (c)Copyright 1993-1995, Sealevel Systems Incorporated
'
'====================================================================
'            BASIC Asynchronous DMA Test Program
'====================================================================

        DATAPORT = &H238                        'ACB Base Adderss
        Control = DATAPORT + 1                  'Channel A CONTROL Port
        ESCC = 0

'====================================================================
'           INITIALIZE THE 8530 SCC
'====================================================================

        READ REG                                'CHANNEL RESET
        OUT Control, REG                        'A AND B
        READ D
        OUT Control, D

        'CHECK FOR PRESENCE OF ESCC (85230)
        OUT Control, 15                         'ENABLE ACCESS
        OUT Control, &H1                        'TO WR7' (TESTING BIT)
        OUT Control, 15                         'WAS WRITE SUCCESSFUL?
        IF (INP(Control) AND &H1) = &H1 THEN    'YES - GO ON...
            OUT Control, 15                     'ENABLE ACCESS
            OUT Control, &H0                    'TO WR7  (TESTING BIT)
            OUT Control, 15                     'WAS WRITE SUCCESSFUL?
            IF (INP(Control) AND &H1) = 0 THEN  'YES - WE HAVE AN ESCC!
                'ESCC DETECTED - TAKE ACTION
                ESCC = 1
                OUT Control, 15                 'ENABLE ACCESS
                OUT Control, &H1                'TO WR7'
                OUT Control, 7                  'EX_READ_ENABLE
                OUT Control, &H50               'AND DTR_REQ_TIMING
                OUT Control, 15                 'ENABLE ACCESS
                OUT Control, &H0                'TO WR7
            ELSE
                'ESCC NOT DETECTED - MUST HAVE 8530
                ESCC = 0
            END IF
        ELSE
            'ESCC NOT DETECTED - MUST HAVE 8530
            ESCC = 0
        END IF

        'FINISH INITIALIZING SCC/ESCC
L1:     READ REG                                'GET REGISTER #
        IF REG = 255 THEN GOTO MENU             'TEST FOR END OF DATA
        OUT Control, REG                        'SET REGISTER #
        READ D                                  'READ DATA
        OUT Control, D                          'SEND DATA
        GOTO L1                                 'LOOP UNTIL DONE

'====================================================================
'                  PRINT THE MENU
'====================================================================

MENU:   CLS
        COLOR 0, 7
        LOCATE 1, 23: PRINT " - BASIC DMA DEMO PROCEDURES - ": COLOR 7, 0
        LOCATE 3, 25: PRINT "1) Receive a block via DMA"
        LOCATE 4, 25: PRINT "2) Transmit a block via DMA"
        LOCATE 5, 25: PRINT "3) Exit"
        LOCATE 10, 23: COLOR 0, 7
        IF ESCC = 1 THEN
                PRINT "Detected an 85230."
        ELSE
                PRINT "85230 chip not detected."
        END IF
        COLOR 7, 0
        LOCATE 7, 25: INPUT "Selection: ", SLECT
       
        SELECT CASE SLECT
        CASE 1: GOTO RXBLOCK
        CASE 2: GOTO TXBLOCK
        CASE 3: CLS : END
        END SELECT
        GOTO MENU

'====================================================================
'                         TRANSMIT A BLOCK
'====================================================================
TXBLOCK:
        CLS
        LOCATE 1, 20
        COLOR 0, 7: PRINT " - BLOCK TRANSMIT ROUTINE VIA DMA - "
        COLOR 7, 0
        LOCATE 3, 1: INPUT "String to transmit: ", BLOCK$
                                                               
        MODE1 = &HC0            'DMA REQUEST ON TRANSMIT
        MODE2 = &H49            'DMA READ TRANSFER
        GOTO SETDMA             'INITILIZE DMA AND START XFER

'====================================================================
'                         RECEIVE A BLOCK
'====================================================================
RXBLOCK:
        CLS
        BLOCK$ = ""
        LOCATE 1, 20
        COLOR 0, 7: PRINT " - BLOCK RECEIVE ROUTINE VIA DMA - "
        COLOR 7, 0
        LOCATE 3, 1: INPUT "Block size to receive: ", BLOCKSIZE

        FOR X = 1 TO BLOCKSIZE
                BLOCK$ = BLOCK$ + " "           'BUILD STRING SPACE
        NEXT X
       
        MODE1 = &HE0                            'DMA REQUEST ON RECEIVE
        MODE2 = &H45                            'DMA WRITE TRANSFER

'====================================================================
'                    INITIALIZE THE DMA CONTROLLER
'====================================================================
SETDMA:
        OUT 10, 5                       'MASK DMA CHANNEL 1

        OUT Control, 1                  'WR1 - DMA REQUEST ON TX OR RX
        OUT Control, MODE1              'SET SCC DMA REQUEST MODE - TX OR RX
        OUT 11, MODE2                   'DMA MODE REGISTER - SET TX OR RX
        N = VARSEG(BLOCK$)              'STRING SEGMENT
        S = SADD(BLOCK$)                'STRING OFFSET
        NEWSEG = (N * 16) + S           'GET 20 BIT ADDRESS
        LBYTE = (NEWSEG AND 255)        'LOW BYTE OF ADDRESS
        SHR8 = (NEWSEG \ 256)
        HBYTE = (SHR8 AND 255)          'HIGH BYTE OF ADDRESS
        DPAGE = ((SHR8 \ 256) AND 15)   'DMA PAGE REGISTER GETS UPPER 4 BITS

        OUT 2, LBYTE                    'SET DMA ADDRESS REGISTER
        OUT 2, HBYTE

        OUT &H83, DPAGE                 'SET DMA PAGE REGISTER

        OUT &HC, 0                      'RESET INTERNAL F/F

        OUT 3, LEN(BLOCK$) - 1          'TRANSFER COUNT - LOW BYTE
        OUT 3, 0                        'TRANSFER COUNT - HIGH BYTE

        OUT 10, 1                       'UNMASK DMA CHANNEL 1 - START TRANSFER

        LOCATE 5, 1: PRINT "Transfer count: "

COUNT:  OUT &HC, 0                      'RESET INTERNAL F/F
        C1 = INP(3)                     'TRANSFER COUNT - LOW BYTE
        C2 = INP(3)                     'TRANSFER COUNT - HIGH BYTE
        CT = C1 + (256 * C2)
        LOCATE 5, 17: PRINT CT          'DMA TRANSFER COUNT
        IF CT <> 65535 THEN GOTO COUNT  'CHECK FOR TRANSFER COMPLETE

        OUT 10, 5                       'MASK DMA CHANNEL 1
        PRINT
        IF MODE1 = &HE0 THEN            'PRINT BLOCK IF IN RECEIVE MODE
                PRINT "Block received: ";
                COLOR 0, 7: PRINT BLOCK$: COLOR 7, 0
                PRINT
        END IF
        PRINT "Transfer complete - press any key to continue"
        DO
        LOOP WHILE INKEY$ = ""

        GOTO MENU
 
'====================================================================
'                    INITIALIZATION VALUES
'====================================================================

        DATA 9, &HC0
                        'FORCE HARDWARE RESET
        DATA 4, &H44
                        'X16 CLOCK MODE, 1 STOP BIT / CHAR
        DATA 3, &HC0
                        'RX 8 BITS / CHARACTER
        DATA 2, 0
                        'INTERRUPT VECTOR - NOT USED
        DATA 5, &H60
                        'TX 8 BITS / CHAR
        DATA 6, 0
                        'ADDRESS - NOT USED
        DATA 7, 0
                        'SYNC FLAG - NOT USED
        DATA 10, 0
                        'NRZ MODE
        DATA 11, &H56
                        'RX CLOCK, TX CLOCK = B.R.G.
        DATA 12, 6
                        'TIME CONSTANT - LOW BYTE - 19.2K BAUD
        DATA 13, 0
                        'TIME CONSTANT - HIGH BYTE
        DATA 14, 3
                        'BAUD RATE GENERATOR ENABLED / SOURCE
        DATA 15, 0
                        'MISCELLANEOUS CONTROL BITS - NOT USED
        DATA 0, &HD0
                        'RESET TX UNDERRUN LATCH AND EXTERNAL/STATUS INTS
        DATA 0, &H10
                        'ERROR RESET
        DATA 0, &H10
                        'ERROR RESET
        DATA 3, &HC1
                        'RECEIVER ENABLED
        DATA 5, &H68
                        'TRANSMITTER ENABLED
        DATA 255
                        'END OF DATA

'====================================================================
'   End of File
'====================================================================