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Protecto-80 cartridge for the VIC-20

CommodoreZ

CommodoreZ

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Not long ago, I was fortunate enough to find a Protecto-80 cartridge for 40 and 80 column modes on the VIC-20.

Problem is that I only get a gray screen, black border, and black cursor on screen, which leads me to believe that I've possibly got a dead character ROM. My research indicates that these mask ROMs (C2H017 or DT8538A) are pin compatible with the 2716 EPROM. I tried to dump both, but only got the one marked VID PAK CG to dump properly. The other one throws PIN DETECT errors, which leads me to believe it's corrupted or damaged. It seems to act like it's partially working, as I can blindly type a simple 10 PRINT "HELLO" 20 GOTO 10 loop, which it seems to comply with, even if I can't see the text on screen. I dropped in a random ROM for the aforementioned ROM that dumped correctly, and saw garbled nonsense on screen, but again, functionally, it followed commands for blindly typed programs correctly. Still, the current hunch is that the character ROM is the point of failure.

Are there any other Protecto-80 owners present who have the ability to dump the ROMs so I can verify one of mine, and possibly recreate one or both to restore this beast back to working order?
 
wow, what software was there in the 80s for 80 column mode?
 
Probably more along the lines of a new video generator chip that supported 40/80 column mode. The best you could get with the stock Vic chip was Screen-40 (which was pretty impressive IMO)
 
The HD chip on the board is 6845 compatible. It was used in various CBM 80xx computers as well. And these have 80 columns as well. The 6845 was used on various video cards for the PC, so no surprise here.
 
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