Ttpilot
Experienced Member
Now that the North Star Horizon motherboard and power are sorted, along with the Compupro CPU-Z and RAM-17 boards, it's time to try to revive the DJ/DMA fdc. Actually, I have two of the boards, so I'm hoping I can get at least one working. I'm starting with the one that I bought off Ebay a year ago. The board works by taking over the bus on startup or reset, using it's onboard Z80 to load the first sector off a floppy and boot from that.
Well, it doesn't boot. The drive doesn't even come on, even though I know it's in working order. The two 7805 regulators are working okay, and the chips are getting power. I checked the Z80 on my breadboard test rig and it's working okay. I checked all the 74 series chips on my TL866 II programmer and they all passed. There are some chips I can't check, such as the 81LS95 and 81LS96. I have a couple of spares of those, so I swapped them out. There is a 2732 EPROM. The programmer can read that, plus the one on the other board, and the stored data matches between them. There are several other chips, including:
Well, it doesn't boot. The drive doesn't even come on, even though I know it's in working order. The two 7805 regulators are working okay, and the chips are getting power. I checked the Z80 on my breadboard test rig and it's working okay. I checked all the 74 series chips on my TL866 II programmer and they all passed. There are some chips I can't check, such as the 81LS95 and 81LS96. I have a couple of spares of those, so I swapped them out. There is a 2732 EPROM. The programmer can read that, plus the one on the other board, and the stored data matches between them. There are several other chips, including:
- 82S105 (labeled DJDMA 2C) (at location 2C on the board)
- 16R4 PAL (labeled DJDMA-2B) (at 2B) This can be read on the programmer as a 16G8 GAL; it looks like it consists of nothing but 1s. The programmer saved it as a .jed file. Tomorrow I'll compare it with the 16R4 on the other board
- 6305 (labeled DJA-3D-2) (at 3D)
- 9401PC (at 4C)
- 6305 (labeled DMA-11C) (at 11C)
- 6301 (labeled DJ-12B) (at 12B)