Apple I

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Apple I - GT-6144 Advert

GT-6144 Subroutine

SUBROUTINE TO SET UP GRAPHICS PIA AND CLEAR SCREEN

[code]
TO ENTER:
IN MACHINE LANGUAGE- JSR $0300
(20 00 03)

IN BASIC - CALL 768

0300- 48 PHA

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.

Drennan on the Graphics Board

Richard Drennan
4590 Oberlin Avenue
Lorain, Ohio 44053
May 5, 1978

Hi Joe.

I finally got my graphics board to work!!! I'm sending along the information
on the graphics that I've been promising you for the last several months.

Interfacing a SWTP GT-6144 to an Apple I

INTERFACING A SWTP GT-6144 GRAPHICS KIT TO AN APPLE I MICROPROCESSOR

 

The STWP graphics board displays a picture made of a 64 X 96 array of rectangles. The schematic I've enclosed is pretty straigt forward. The .006 MFD capacitor connected between pins 6 and 7 of the 74123 controls the length of time that must elapse between each output of date to the GT-6144. I've been unable to load the date faster than the .005 capacitor will allow.

GT-6144 Graphics Board

The Apple I's onboard video memory was capable of displaying text only. With the addition of the GT-6144 Graphics Board, the Apple I could display primitive black and white graphics.

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Datanetics pricing

Datanetics

February 16, 1978
78-DH-S1558

Mr. Joe Torzewski
51625 Chestnut Road
Granger, IN 46530

Datanetics Corp Keyboard

Apple I - Datanetics keyboard

The keyboard most commonly used with the Apple 1 was the Datanetics Corp keyboard.

Apple I - Datanetics logo

The Datanetics Corp logo.

Apple I - Datanetics date

Expanding the Memory to 20k

INSTRUCTIONS FOR EXPANDING THE APPLE-1 MEMORY TO 20K

The procedure consists of replacing one row of type 4096 memory chips (the X
row) by 4116 chips, each of which has a capacity of 16384 bytes rather than

Upgrading the Memory

Apple I board

Note the bread board area at the left of the top-most blue capacitor.

Apple I - breadboard area

The 74153 and 74139 chips on the bread board area on the Apple 1 computer, as mentioned on the next page.

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