I/O Interface

Discuss the CreatiVision hardware: models, revisions, fixing, hacking and modding.
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Mobsie
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I/O Interface

Post by Mobsie » Mon Dec 09, 2013 4:34 pm

today i give the I/O interface to one of my hardware guru. This is the last he made for me, is the Enterprise 128 Diskcontroller.
Foto 1.JPG
So the CV I/O is easy.
Foto 2.JPG
Here is really not much to do.
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Mobsie
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Re: I/O Interface

Post by Mobsie » Mon Dec 09, 2013 5:03 pm

the big one on the pictures is a Hitachi HD468B21P PIA, also standard.
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Mobsie
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Re: I/O Interface

Post by Mobsie » Wed Dec 11, 2013 10:11 pm

i am finish now with the analyze of the I/O Interface. I have now the pinout for the big port.
I also make a interface to connect 3 led´s and write a program to let them blink. Not a big step but the beginning…
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Mobsie
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Re: I/O Interface

Post by Mobsie » Sun Dec 15, 2013 11:39 am

today i have success with reading from the i/o interface parallel port. This is great because not all centronics from old days are bi-directional. The PIA 6821 yes, but some boards have wrong buffer and bi-directional is not possible then.
On the CV we can use all 8 Data Pins as output or input, and any mix. My test-board with 4 LED on the output pins, and 4 transistor switch on the input pins work perfect. Now we can begin with high-speed communication.
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MADrigal
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Re: I/O Interface

Post by MADrigal » Sun Dec 15, 2013 6:11 pm

This is really great news indeed!

What are your plans? A modded version of the BASIC, capable of storing/loading data to/from a floppy disk drive?
Clockmeister
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Re: I/O Interface

Post by Clockmeister » Tue Dec 31, 2013 12:14 am

Mobsie wrote:today i have success with reading from the i/o interface parallel port. This is great because not all centronics from old days are bi-directional. The PIA 6821 yes, but some boards have wrong buffer and bi-directional is not possible then.
On the CV we can use all 8 Data Pins as output or input, and any mix. My test-board with 4 LED on the output pins, and 4 transistor switch on the input pins work perfect. Now we can begin with high-speed communication.
How are you reading/writing to the output pins? Poking/peeking specific memory locations?
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Mobsie
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Re: I/O Interface

Post by Mobsie » Tue Dec 31, 2013 8:12 am

the i/o interface use the PIA 6821, but ONLY PortB. PortA is not used. At the address $E800 and $E801 (59392 and 59393) you can program the PIA. Each of the 8 i/o pins can be defined at input or output. As Input test with an 1.1k switch. Thats all.
Clockmeister
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Re: I/O Interface

Post by Clockmeister » Tue Dec 31, 2013 12:05 pm

Easy. Thanks for that, time to experiment to see if my i/o interface works.
I have plenty of spare 6821's at hand...
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Mobsie
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Re: I/O Interface

Post by Mobsie » Tue Dec 31, 2013 12:06 pm

thats cool you have that pia. i have now ordered 10, not easy to find.
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