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CONTRIBUTIONS/cpm-handbook/cpmsrc/FIG8-6.ASM

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+;	Figure 8-6
+;
+;	Device Table Equates
+;	The drivers use an Device Table for each
+;	Physical Device they service. The EQUates that follow
+;	are used to access the various fields within the
+;	Device Table.
+;
+;			Port Numbers and Status Bits
+DT$Status$Port		EQU	0	;Device Status Port number
+DT$Data$Port		EQU	DT$Status$Port+1
+					;Device Data Port number
+DT$Output$Ready		EQU	DT$DataPort+1
+					;Output ready status mask
+DT$Input$Ready		EQU	DT$Output$Ready+1
+					;Input ready status mask
+DT$DTR$Ready		EQU	DT$Input$Ready+1
+					;DTR ready to send mask
+DT$Reset$Int$Port	EQU	DT$DTR$Ready+1
+					;Port number used to reset an
+					;  interrupt
+DT$Reset$Int$Value	EQU	DT$Reset$Int$Port+1
+					;Value output to reset interrupt
+DT$Detect$Error$Port	EQU	DT$Reset$Int$Value+1
+					;Port number for error detect
+DT$Detect$Error$Value	EQU	DT$Detect$Error$Port+1
+					;Mask for detecting error (parity etc.)
+DT$Reset$Error$Port	EQU	DT$Detect$Error$Value+1
+					;Output to port to reset error
+DT$Reset$Error$Value	EQU	DT$Reset$Error$Port+1
+					;Value to output to reset error
+DT$RTS$Control$Port	EQU	DT$Reset$Error$Value+1
+					;Control port for lowering RTS
+DT$Drop$RTS$Value	EQU	DT$RTS$Control$Port+1
+					;Value, when output, to drop RTS
+DT$Raise$RTS$Value	EQU	DT$Drop$RTS$Value+1
+					;Value, when output, to raise RTS
+;
+;		Device Logical Status (incl. Protocols)
+DT$Status		EQU	DT$Raise$RTS$Value+1
+					;Status Bits
+DT$Output$Suspend	EQU	0000$0001B	;Output suspended pending
+						;  Protocol action
+DT$Input$Suspend	EQU	0000$0010B	;Input suspended until
+						;  buffer empties
+DT$Output$DTR		EQU	0000$0100B	;Output uses DTR high to send
+DT$Output$Xon		EQU	0000$1000B	;Output uses Xon/Xoff
+DT$Output$Etx		EQU	0001$0000B	;Output uses Etx/Ack
+DT$Output$Timeout	EQU	0010$0000B	;Output uses Timeout
+DT$Input$RTS		EQU	0100$0000B	;Input uses RTS high to receive
+DT$Input$Xon		EQU	1000$0000B	;Input uses Xon/Xoff
+;
+DT$Status$2		EQU	DT$Status+1	;Secondary Status Byte
+DT$Fake$Typeahead	EQU	0000$0001B	;Requests Input$Status to
+						;return "Data Ready" when
+						;Control Characters are in
+						;input buffer
+;
+DT$Etx$Count		EQU	DT$Status$2+1
+					;No. of chars sent in Etx protocol
+DT$Etx$Message$Length	EQU	DT$Etx$Count+2
+					;Specified message length
+;
+;			Input Buffer values
+DT$Buffer$Base		EQU	DT$Etx$Message$Length+2
+					;Address of Input Buffer
+DT$Put$Offset		EQU	DT$Buffer$Base+2
+					;Offset for Putting chars into buffer
+DT$Get$Offset		EQU	DT$Put$Offset+1
+					;Offset for Getting chars from buffer
+DT$Buffer$Length$Mask	EQU	DT$Get$Offset+1
+					;Length of buffer - 1
+					;Note : Buffer length must always be
+					;  a binary number; e.g. 32, 64 or 128
+					;This mask then becomes :
+					;  32 ->  31 (0001$1111B)
+					;  64 ->  63 (0011$1111B)
+					; 128 -> 127 (0111$1111B)
+					;After the Get/Put offset has been
+					;incremented it is ANDed with the mask
+					;to reset it to zero when the end of
+					;the buffer has been reached.
+DT$Character$Count	EQU	DT$Buffer$Length$Mask+1
+					;Count of the number of characters
+					;  currently in the buffer
+DT$Stop$Input$Count	EQU	DT$Character$Count+1
+					;Stop input when the count reaches
+					;  this value
+DT$Resume$Input$Count	EQU	DT$Stop$Input$Count+1
+					;Resume input when the count reaches
+					;  this value
+DT$Control$Count	EQU	DT$Resume$Input$Count+1
+					;Count of the number of control
+					;  characters in the buffer
+DT$Function$Delay	EQU	DT$Control$Count+1
+					;Number of clock ticks to delay to
+					;  allow all characters after function
+					;  key lead-in to arrive
+DT$Initialize$Stream	EQU	DT$Function$Delay+1
+					;Address of byte stream necessary to
+					;  initialize this device
+