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uPD7220 GDC prototype PCBs

NobodyIsHere

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Dec 21, 2006
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2,394
Hi! I just received a batch of the N8VEM ECB uPD7220 GDC boards. They are the second iteration prototypes based on the feedback and correcting the errors found in this last summer's first uPD7220 prototype board.

The new board is SRAM based with four bit planes for 16 colors and also uses a RAMDAC for display. This is a prototype board so there are only about ten boards total of which three have already gone out.

If anyone is interested in some uPD7220 GDC experimenting here is your chance. There are not many uPD7220 GDC video boards out there any more and this is the only one using SRAM AFAIK.

The uPD7220 GDC was popular early in the microcomputer era (late 1970's early 1980's) as an intelligent graphics controller. Unfortunately it was subsumed by the rise of the IBM PC and CGA graphics card although the concept reappeared about 10-15 years later as accelerated graphics boards and GPUs.

There were at least a few uPD7220 GDC based S-100 graphics boards although *none* of the manuals/schematics have been preserved as far as I can tell. They really are a rare creature and it made researching this board quite a challenge.

Eventually this will result in a "production" N8VEM ECB board as soon as we work out out the kinks in this design. The modifications necessary to fix the first iteration board were pretty dramatic so I am hoping this one will go smoother.

Thanks and have a nice day!

Andrew Lynch
 

NobodyIsHere

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Dec 21, 2006
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Hi! Good news on the uPD7220 V2 prototype board! This week it finished build and test. It works fine with some very minor corrections. It produces a beautiful 640x480 at 16 colors with VGA monitor compatibility. It can also run 800x600 with an oscillator upgrade and some software changes.

There are some photos on the N8VEM wiki. Please note the wiki is in the process of a long overdue reorganization and clean up. You'll find the files in the board support > ECB > ECB uPD7220 V2 directory.

Next hopefully we will be porting GSX (a CP/M relative prior to GEM) to the uPD7220 board so that will be neat. Let me know if anyone is interested in joining up. This is going to be a fun project!

Thanks and have a nice day!

Andrew Lynch
 

NobodyIsHere

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Joined
Dec 21, 2006
Messages
2,394
Hi! Since the uPD7220 V2 board is working nicely now I would like to kick off the GSX porting project. For those unfamiliar with GSX, it is a graphical user interface for CP/M and a predecessor to GEM. There are both CP/M-80 and CP/M-86 versions of GSX and both are possible for the N8VEM project. The N8VEM SBC V2 would run GSX-80 and the SBC-188 would run GSX-86. Both would use the uPD7220 although I suppose ports to the SCG (TMS9918) or PropIO would be possible at least in theory.

There are some GSX files about on the internet and I have additional information if you are interested. If we are successful this port of GSX could help other computer projects revitalize this tangential OS development. Almost all CP/M systems I am aware of are text only so this could be quite exciting!

Thanks and have a nice day!

Andrew Lynch
 

NobodyIsHere

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Joined
Dec 21, 2006
Messages
2,394
Hi! I am giving away the remaining uPD7220 GDC prototype boards. If there is anyone interested in working on a 7220 GDC project please let me know. These boards are designed for ECB although will interface to any Z80 quite easily. Other systems would take some work but still possible.

Also, there is a page on the N8VEM wiki for the uPD7220 V2 prototype board with schematics, PCB layout, test software, etc. There will be a new board coming out soon but these prototype boards work fine with some very minor tweaks.

For more details see here

http://groups.google.com/group/n8vem/t/2b566d452dd7b460

Thanks and have a nice day!

Andrew Lynch

PS, pair this board up with an SBC-188 or your homebrew 8088 board and we could have a completely free/open FreeDOS/OpenGEM solution!
 
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