I/O Interface

Mobsie · 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.

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

the big one on the pictures is a Hitachi HD468B21P PIA, also standard.

Mobsie · 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…

Mobsie · 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.

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 · 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?

Mobsie · 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 · 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...

Mobsie · 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.

@username@ · Post by **@username@** » Thu May 23, 2024 4:32 pm

Forgive me if it's already posted here - is there a datasheet for the creatiVision I/O interface?

Just curious to know if the secondary interface tracks back to the PIA.

Cheers!

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