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 Post subject: Problems flashing 1/8 MBit Carts on some Computers
PostPosted: Fri Dec 17, 2010 8:13 am 
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Joined: Fri Dec 17, 2010 6:46 am
Posts: 5
Hi @ all

If you have Problems flashing Carts on your Computer , please read this.

The reason is the PHI2 Signal, is on some Machines too long for the Atarimax Carts. My 800XE Pal recognized the 8MBit Cart(black Case) often as 4MBIT. Erasing works, but when you begin to flash, then you get an Error "Verification fail "!

You can fix the Problem with a simple Wire-Bridge on the 74LS08.

Look @ that:

The 02 (phase two) clock signal that comes out of the computer through the cartridge (and PBI) port(s) is buffered from the signal coming directly from the CPU. This buffering adds a small but measurable delay. By the time the signal gets out of the computer and on to your PBI devices, there is more inductance and parasitic capacitance to further delay this signal. When the delay gets too much out of hand, WRITES to the PBI device get corrupted, because the data bus is no longer valid on the trailing edge of 02. I used to swap out the 6502, which would generally fix the problem. However, I found a solution that would work with ALL processors: add in the phase 0 clock input (that goes into the 6502's clock circuit) into the 02 buffer gate. the phase 0 signal is the same as the phase 2, only backwards in time slightly. It so happens that the 02 buffer gate is an AND gate, and has an unused input. Tying this unused input to the phase 0 signal ends up bringing the high-to-low transition back in time, giving us a little more grace for the extra delays that will happen in the outside world.

ON 600XL COMPUTERS: Solder a wire from pin 4 of the 74LS08 to pin 2 of this same chip

ON 800XL COMPUTERS: Solder a wire from pin 4 of the 74LS08 to pin 13 of this same chip

ON 65XE/130XE COMPUTERS: Solder a wire from pin 4 of the 74LS08 to pin 2 of this same chip

It works great for me !

errors excepted, im not responsible for internal damage !

Greetz
Zaxxon-HH


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