Handy and educational electronics for vintage computing enthusiasts.
Test vintage parallel ASCII keyboards with ease and see how they actually work.
It uses LEDs for display. See the
8-bit data and
strobe signals coming from the keyboard. Watch the
strobe signal going high to low (or vice versa). Additionally, the
clear signals can be tested for the Apple-1 and Apple ][.
The board needs a 5V power supply as a minimum, but some keyboards need -12V and/or +12V to operate. Onboard is a passthrough power out connector for the keyboard. Connect an Apple-1 or Apple ][ keyboard directly using the DIP-16 connectors. The extra data-in connector can be used to connect uncommon or custom keyboards.
Use the bread board area to add your own experiments!Manual New Schematics Bill of Materials Order now!
Display the hex value (two digits,
0-F) of any parallel 8-bits TTL input.
Mount it on top of the ASCII Keyboard Tester, or use it stand alone. The jumper can be used to enable (or disable) the 8th bit. Using this jumper, both ASCII values (7 bits) and full bytes (8 bits) can be displayed correctly. The board needs a 5V power supply when used stand alone.Schematics Bill of Materials Order now!
Discover how an Apple-1 or Apple ][ generates a single character for display.
The character is displayed on the
5x7 dot matrix display. See the
row address LEDs counting and how the display is being built up by stepping through the seven horizontal scan lines. The clock speed can be adjusted manually when the stepping function is disabled. Connect an Apple-1 or Apple ][ keyboard directly using the DIP-16 connectors, or use the ASCII Data In pins. Verify the ASCII input to the character generator using the
character address LEDs.
A power supply with +5V and -12V is needed as a minimum. The -5V is regulated on the board itself. Provide +12V when this voltage is needed by the attached keyboard. It supports a variety of character generators: the
2716 EPROMs and
2816 EEPROMs. Connect the
8-bit counter output to use the output of the clock with the ASCII Keyboard Tester and/or the One Byte Hex Display.
The process is old-fashioned simple.
You can choose for a plain PCB (purple, green on request) or a complete kit. The kit contains the PCB and all parts needed (unsoldered). See the bill of materials for the parts included.
|ASCII Keyboard Tester
|One Byte Hex Display
|Character Generator Tester New
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