
;  This section defines the constants used to identify ports, bits, 
;  and other constant elements of the BIOS environment.



;  Port assignments
;  ---- -----------

CNT_MDM   .EQU  8BH                ;  Clock divider for serial
;                                     port controllers.

CNT_REG_0 .EQU  88H                ;  Counter register 0.

CNT_REG_1 .EQU  89H                ;  Counter register 1.

CNT_REG_2 .EQU  8AH                ;  Counter register 2.

CRT_DATA  .EQU  0A8H               ;  CRT data port.

CRT_STAT  .EQU  0A9H               ;  CRT status port.

DIA_DATA  .EQU  86H                ;  Output to printer.

DIA_STAT  .EQU  87H                ;  Printer status register.

DMA_CTL   .EQU  0B8H               ;  DMA mode port.

DMA_ADR   .EQU  0B0H               ;  DMA address entry port.

DMA_TCNT  .EQU  0B1H               ;  DMA terminal count.

FDC_DATA  .EQU  0A1H               ;  FDC command and results.

FDC_INT   .EQU  0A2H               ;  [7] indicates FDC command
;                                     completion.

FDC_STAT  .EQU  0A0H               ;  FDC status.

PRT_DIA   .EQU  86H               ;  Diablo printer port address, KGB
;                                     config.

PRT_MODEM .EQU  84H                ;  Modem controller address, cur-
;                                  rently not implemented.

;  Disk Control Parameters
;  ---- ------- ----------

FDC_ONLIN .EQU  5                  ;  Ready in SR3.

FMT_SKEW  .EQU  7                  ;  Sector skew to apply to disk
                                   ;  formatting--Pascal interleave and
                                   ;  skew are [1:0].

MFD_INTL  .EQU  1                  ;  Interleave for single-sided disks.

MFD_SKEW  .EQU  0                  ;  Skew for single-sided disks.

DSK_RETRY .EQU  5                  ;  Number of errors to allow before
                                   ;  reporting CRC failure.

;  Serial Board Control Parameters
;  ------ ----- ------- ----------

DIA_SPEED .EQU  13                 ; Speed divisor for Diablo 630 printer
                                   ; --9600 Baud.

PRT_DSR   .EQU  7                  ; Device on-line flag.

MDM_SPEED .EQU  13                 ; Dummy: no current modem device.

PRT_RRDY  .EQU  1                  ; Receive register full.

STAT_PRT  .EQU  1                  ; Offset of Status serial port.

PRT_RTSB  .EQU  0                  ; Ready to send.

PRT_THBE  .EQU  2                  ; Transmit buffer empty.


;  Disk Control Block Offsets
;  ---- ------- ----- -------


;  Phone Port Offsets
;  ----- ---- -------


;  Phone Control Parameters
;  ----- ------- ----------


;  ASCII Character Codes
;  ----- --------- -----

ACR       .EQU  0DH                ;  <Carriage return>.
AESC      .EQU  1BH                ;  <Escape>.


