ISA video board version 2

This board is a more advanced version, its 16 bit and has 24 adress bits. This is to make a larger framebuffer possible above 1Mb. This card will be used in a 80486 computer that will be running a DJGPP development enviroment.

Specifications

The board will have the following capabilites:

VGA resolution 640*480 at 60 Hz (with a 25.175MHz oscillator) or 640*480 at 68Hz (with a 28.3220MHz oscillator).
15 bit color with a real resolution of 320*240.
1024kb videoram for multiple video pages.
Wait state generation

The board will be built out of the following:

1 XC95288XL-C10 TQ144 CPLD
1 MB static ram simm memory module IDT7MP4145
1 * 74F573 Latche

Here are a few pictures. More information coming up soon.

Card setup attached to a LCD screen, the pattern is a generic x*x+y*y pattern.

This is a (Blurry) closeup from the card, the copper heatsink has been placed on the CPLD becouse i dont like things that are running hot.

Nice closup from the TQFP adapter.

Update

I have made some modifications to the pin outs, but more importantly i have attached the memory to the board. It consists of a Special Simm memory that consists of SRAM chips. I got mine off ebay that seemed to have a whole pile of them. They where quite cheap at 4 dollars a piece as i recall. They add 1Mebi(2 to the power20) bytes of memory, and is organised in 256K words of 32 bits. I am only using the upper half of the datawords, the other lines still need to be soldered on the board.

More action shots and underside shots coming up.

The Current verilog source code can be downloaded here. It contains the main VGA signal generation statemachine, and memory interface. The UCF file is added for completeness.
Videocard 2.0 sourcecode

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Last update at: 15-01-2006