8302<>8049 communications...

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Dave
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Re: 8302<>8049 communications...

Postby Dave » Wed Feb 07, 2018 4:26 pm

I apologize humbly. I made a typo. I am trying to replace the 8049. Not the 8032.

I am looking to do this with an ESP32S. It is TTL friendly as output, and is 5V tolerant on some inputs. That said, a simple level shifter is justified. The keyboard matrix will happily run off 3v3. Serial can be moved to a UART. BEEP can be recreated.

The 8302 is also replaceable, but requires more work. We don't need to worry about serial or microdrives. The QLNET is useful. Clock and reset functionality is critical but trivial to shift off.
Last edited by Dave on Wed Feb 07, 2018 10:37 pm, edited 2 times in total.


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Re: 8302<>8049 communications...

Postby Dave » Wed Feb 07, 2018 4:28 pm

Pr0f wrote:That's slightly cheating as it has a couple of voltage translators on board. However, Dave is gifted in the hardware design area, so a 3.3V i/O based FPGA with some form of input conditioning, or a 5v tolerant device such as the device used in the QL_SD board (Lattice 4000 series?) - I know that's a CPLD, but the 4128 and 4256 have a good number of macro cells for building logic from.


It's not cheating! :P

Also, I would not say I am gifted. I would say Nasta was gifted.


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Re: 8302<>8049 communications...

Postby tofro » Wed Feb 07, 2018 10:11 pm

Dave wrote: The QLNET is useful.


The 8049 is not involved with QLNET.

Tobias


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Re: 8302<>8049 communications...

Postby Dave » Wed Feb 07, 2018 10:39 pm

tofro wrote:
Dave wrote: The QLNET is useful.


The 8049 is not involved with QLNET.


I did, of course, mean the 8302! I jumble them up a LOT. Both four digit numbers beginning with 4 and having a 0 in the middle. I see the 8049 as a simple IO expander for the 8302.

(Note: I mixed them up in this post too, and rechecked it before posting!)


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Re: 8302<>8049 communications...

Postby Peter » Thu Feb 08, 2018 1:57 pm

Pr0f wrote:
Peter wrote:
Pr0f wrote:There are a number of small FPGA boards arround that could probably fill the role of the ZX8302/8049 as a combo and be plug in compatible to the 8302 socket.

Examples would be welcome! I don't know any available FPGA board with 5V tolerance. Let alone a board which is small enough to plug into that DIL socket.

Peter


https://shop.trenz-electronic.de/en/Pro ... nik/GODIL/

Thanks. An FPGA board with level shifters indeed. Although I don't think it would be useable (price and dimensions).

I had at some time considered an FPGA board for th 68008 socket, allowing decent video, but the level shifter / space issue made it problematic.


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Re: 8302<>8049 communications...

Postby Pr0f » Thu Feb 08, 2018 2:44 pm

Peter wrote:
Pr0f wrote:
Peter wrote:Examples would be welcome! I don't know any available FPGA board with 5V tolerance. Let alone a board which is small enough to plug into that DIL socket.

Peter


https://shop.trenz-electronic.de/en/Pro ... nik/GODIL/

Thanks. An FPGA board with level shifters indeed. Although I don't think it would be useable (price and dimensions).

I had at some time considered an FPGA board for th 68008 socket, allowing decent video, but the level shifter / space issue made it problematic.


Yes - it's a nice idea, but with a limited number of pins - 40 or 48 and no access to the other pins on the FPGA, it does limit functionallity to what you can put in the FPGA. But the module does allow power and ground to be selected for several pins, so it will replace any 40 pin or 48 pin device. Dimension wise, they aren't much bigger than the DIP footprint they plug into.

But it's a good way of replacing / enhancing a ULA in an old retro machine...


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Re: 8302<>8049 communications...

Postby Dave » Thu Feb 08, 2018 8:12 pm

I have some 5v tolerant ispMACH 4000v devices - but there's an ever growing selection of level shifters... Also, resistor dividers for input or transistors for output can be very cheap these days. However, the device I chose is tolerant to 5.5v if run off 3.6v and 5.2v if run off 3.3v.



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