49 lines
3.1 KiB
Plaintext
Vendored
49 lines
3.1 KiB
Plaintext
Vendored
Name SFD700_GAL2 ;
|
|
PartNo GAL16V8 ;
|
|
Date 22/05/2023 ;
|
|
Revision 01 ;
|
|
Designer Philip Smart ;
|
|
Company engineers@work ;
|
|
Assembly SFD700 ;
|
|
Location ;
|
|
Device g16v8 ;
|
|
|
|
/* *************** CONSTANTS ********************** */
|
|
$DEFINE ON 'b'1
|
|
$DEFINE OFF 'b'0
|
|
|
|
/* *************** INPUT PINS ********************* */
|
|
PIN 1 = CLK ; /* Registered clock input */
|
|
PIN 2 = A10 ; /* Address bus A10 */
|
|
PIN 3 = A11 ; /* A11 */
|
|
PIN 4 = A12 ; /* A12 */
|
|
PIN 5 = A13 ; /* A13 */
|
|
PIN 6 = A14 ; /* A14 */
|
|
PIN 7 = A15 ; /* A15 */
|
|
PIN 8 = !MREQn ; /* Z80 MREQ active low */
|
|
PIN 9 = !RDn ; /* Z80 RD active low */
|
|
PIN 12 = MODESEL0 ; /* Mode selection bit 0 */
|
|
PIN 13 = MODESEL1 ; /* Mode selection bit 1 */
|
|
PIN 14 = ROMINH ; /* Rom select inhibit */
|
|
PIN 15 = ROMDIS ; /* Rom select disable */
|
|
PIN 16 = DRQ ; /* FDC Data Request */
|
|
|
|
/* *************** OUTPUT PINS ******************** */
|
|
PIN 17 = ROMA15 ; /* ROM A15 */
|
|
PIN 18 = ROMA10 ; /* ROM A10 */
|
|
PIN 19 = !ROMCSn ; /* ROM Chip Select */
|
|
|
|
/* Decoder equations. */
|
|
FIELD HIADDR = [A15..A12] ; /* Address lines considered for ROM device. */
|
|
ROMOUTSEL = MREQn & RDn & HIADDR:[F000..FFFF] & !ROMDIS & !ROMINH ; /* Rom Select. */
|
|
|
|
/* Assign output pins based on equations. */
|
|
ROMCSn.D = ROMOUTSEL ;
|
|
ROMA15.D = MODESEL1;
|
|
ROMA10.D = (MODESEL1 & ROMOUTSEL & !A10) # (!MODESEL1 & ROMOUTSEL & DRQ);
|
|
MODESEL0.OE = OFF;
|
|
MODESEL1.OE = OFF;
|
|
ROMINH.OE = OFF;
|
|
ROMEN.OE = OFF;
|
|
DRQ.OE = OFF;
|