|
Text Card
The
video displayer circuit is based on a
2k*8 dual-port RAM for video, A
programmable sync generator, and an 8k*8
character font ROM.
I originally made this project for
the old VIC-20 bus. Later, I migrated it
to the ISA bus and 8051 MCU bus.
|
|
Here is the ISA/MCU version.
|
| A QBASIC program is provided to
communicate with the card through the ISA
bus. For this purpose, the 2*31 header at
the bottom connects to an ISA edge board
converter. Firmware is provided for the
MCU with an equivalent to the QBASIC
version plus a game.
|
| The circuit also has a 128*100
graphic capability.
click here to
download all project files
parts used: 74ACT715 IDT7142
|
 Graphics
Card
This is a
circuit that uses discrete logic to
generate color graphics. The
video memory map is compatible with
that of a CGA video adapter.
|
The right side
screens show a circle drawn by Qbasic
command in CGA compatible video modes on
standard PC video hardware. The left
side screens show the result of copying
the video frame buffer directly from the
standard frame buffer to the frame
buffer belonging to the hardware that I
built.  
|
Here is the graphics
card, built on an ISA protoboard. Like
the text version, this one is also based
around a dual-port RAM and a 74ACT715
sync generator.
click here to
download all project files
74ACT715 74HCT670 CY7C006 GAL16V8
GAL22V10
|
