If you have a GT-61 (GT-6144) that you would consider selling or offering in trade, please contact Tom Owad at owad@applefritter.com. Thank you!

SWTP GT-6144 Interface Schematic

This information is taken from the schematic for the hook up of the Apple1 to the SWTP GT-6144 graphics board, refer to it while reading this, especially on the PIA pins , 23, 34, 35, 37 and 38.

The chip on the left is for the PIA for the graphic board. All pins marked with a * are connected to the corresponding pin on the keyboard PIA, pins 1, 20, 21, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36. This is listed at the bottom of the sheet on the left side. Pin 22 goes to the address line A3.

The capacitor on the 74123, between pins 6 and 7. On the bottom of the sheet on the right hand side says, ì you may have to play with this capacitor a little. The capacitor governs the length of time that must elapse between each output of data to the GT-6144.

The 12 pin molex connector on the GT-6144 board is shown on the right side of the sheet.

The information right below the 12 pin molex connector has the 6820-6520 PIA pins.

1 = VSS 11 = PB1 21 = R/W 31 = D2<br /> 2 = PA0 12 = PB2 22 = CS1 32 = D1<br /> 3 = PA1 13 = PB3 23 = CS3* 33 = D0<br /> 4 = PA2 14 = PB4 24 = CS2 34 = RESET*<br /> 5 = PA3 15 = PB5 25 = ENABLE 35 = RS1*<br /> 6 = PA4 16 = PB6 26 = D7 36 = RS0<br /> 7 = PA5 17 = PB7 27 = D6 37 = IRQB*<br /> 8 = PA6 18 = CB1 28 = D5 38 = IRQA*<br /> 9 = PA7 19 = CB2 29 = D4 39 = CA2<br /> 10 = PB0 20 = VCC 30 = D3 40 = CA1



Click to enlarge: Apple I - GT-6144 Interface Schematic

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