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F18A MK2


matthew180

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Very nice! Having the extra vram for 80 column/text2 mode could be very beneficial for the programs that are too difficult to modify. If you allow for the blink attribute, even better.

 

V9938 potential aside, it seems to me the most important achievements are the updated electronics, reduced size, extra memory, and the more current video output method.

 

Thanks for spilling the beans!

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First, thank you to everyone for the kind words and comments. Now I just have to get through two pages of questions... I suppose that's what I get for posting this in the middle of the night and going to bed, then work all day. icon_winking.gif

Will this, in fact, replace the 9938 (i.e., can I plug it in and use 9938 dependent programs)?


Not with the firmware that will be in the first release. The MK2 boards that will hopefully ship in July will be the same core functionality as the current F18A. I am planning on a 38/58 compatible firmware, with hopefully some sort of way to also include the F18A enhancements. But I have not worked all of that out yet. Also, the MK2 pin-out is still that of the 9918A. For a true 9938/58 plug-in replacement, I'm planning on a carrier-board for the MK2 that will adapt to the 9938 pin-out. But I have a lot of work to do to get to that point.

I notice the micro HDMI connector on the F18A MK2... will there be a jumper/converter included cable included that will attach to a PC style plate?


No, you will need to provide you own HDMI cables, adapters, back-planes, etc. But because HDMI is so prevalent, and products like the GoPro use micro-HDMI, there are tons of cheap options out there. Right now for testing I'm using a short Type-D to Type-A HDMI adapter that I got from Amazon for about $8. But if you do an Internet image search for Micro-HDMI or HDMI Type-D, you will see piles of products.

If I were to put one in my Colecovision, could I swap it into the TI to do the firmware update?


Yes you could. However, as Tursi already mentioned, he ported the F18A updater to the CV already. I am also planning on a USB-update option via an extra board that could be purchased separately. That is probably not as appealing as the in-system update, but as much as I wanted to have on-board USB for the MK2, there was just not enough room.

Now, if he updated the core to support everything on the 9938, then that does open other opportunities.


There is a plan for 38/58 features support, but I have not worked out all the details on exactly how that will happen yet. I will probably be having some open discussions on that topic in the future.

Great news. Sounds like I will be able to finish my raycaster.


That would be awesome, then I don't have to do it. icon_winking.gif

What HDMI video mode does it use? (I'm hoping 720p60) Could you post a pic of how it looks on a monitor?


The HDMI specification very specifically says *all* HDMI displays *will* support 640x480@60Hz, so that is the HDMI mode. All the HDL I currently have, plus the HDMI core I am writing are designed for 640x480, and I'm trying to get things done and out the door rather than rewrite it all over again. Sorry. Nothing is gained by going to 720. I will post some screen shots soon, but it really does just look like the VGA display.

Hope the features do offer 4 times the pixels in Graphics modes like Bit map in 9938/9958???


With the 512KiB SRAM the MK2 has the ability to offer a 640x480 display with 256-colors per pixel. That would be a single buffer though, and a lot of pixels for the host computer to push around. As mentioned previously, I still have to work out if it will be possible to mix 38/58 functionality with F18A features, plus the new possibilities of the MK2.

Are the GPIO pins shared with the other pins?


One of the reasons the MK2 has taken so long to develop is because I could not leave things alone, like leaving all those extra pins unconnected. icon_winking.gif The MK2 uses 38 of the 40 pins on the package. The pins needed for the host interface, i.e. CD0..7, MODE, #CSW, #CSR, #INT, RESET, CPUCLK, GROMCLK, 5V, and GND are all as they should be, and those I/Os are all dual-voltage level shifted (unlike the F18A that used a single-voltage level shifter, and only level-shifted the inputs and CD0..7.)

The other pins on the 9918A were for interfacing with the DRAM chips, and conveniently they were all outputs from the 9918A, except for the 8-bit bi-directional data bus to the DRAM (which the 9918A actually controls via the #RAS, #CAS, and R#W pins to the DRAM). Thus, since these are outputs from the VDP in all systems that use the 9918A family, I can safely make those general purpose I/O on the MK2, since in a retro computer they will never be driven by the host (note that these extra I/Os are *not* level-shifted). The only two exceptions are the two XTAL input pins, and since I did not want to add "yet another level shifter" for those two pins, they are left unconnected.

All that to say, no, the 14 extra GPIOs are not shared with anything, and it has already been requested that they be exposed to the GPU. :-)

Wow! Now if it could do 50hz that would be really awesome, but I suspect not.

Sorry, no 50Hz. Too much of a hassle since it ties in to more than just video output. Video is not easy, and there really are other things I want to do in life other than implement all the possible permutations of all the video modes of all the retro computer systems. :-)

 

 

I did not proof any of this, so I hope it is all correct. ;-)

 

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Very nice! Having the extra vram for 80 column/text2 mode could be very beneficial for the programs that are too difficult to modify. If you allow for the blink attribute, even better.

 

V9938 potential aside, it seems to me the most important achievements are the updated electronics, reduced size, extra memory, and the more current video output method.

 

Thanks for spilling the beans!

 

Blink, bah! ;-) I implemented blink support way back when I was first implemented T80, and I removed the HDL. Just like the HTML blink-tag, blink should not exist. :-)

 

However, depending on how the 38/58 and F18A features are made to work together, blink will probably be included.

 

Definitely IMO the board-size and HDMI output are the most important new features from a compatibility and usability perspective.

 

Also, removing all the through-hole headers means I can have the entire board machine-assembled instead of having to solder all those headers. Yes, I hand-soldered all those headers on over 500 F18A boards! It was getting really old.

 

It really bothered me that the F18A could not be used in some computers due to the size. The MK2 fixes that.

 

The SRAM I took as a challenge. I was totally done with the design, but it was still lacking the memory necessary to implement the 38/58, as well as the higher color and pixel features I wanted to add. So I found a suitable SRAM chip, pushed things around on the board, and started routing. Somehow I managed to pull it off, but I had to really push the size down on everything.

 

The only downside so far is, because of the small size, audio input support, and external SRAM, the cost will not be any lower (and will probably be a little more) than the original F18A.

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Is the audio routed in a way that makes it possible for the F18A to modify it?

 

Of course. :-)

 

Pin 1 of the MK2 goes to an op-amp pre-buffer, then to an ADCS-7476 (12-bit) ADC. The FPGA samples the input audio at 48KHz and expose the data to the GPU in some yet to be determined manner. Mixing or sending that audio sample out the HDMI interface could be controlled by the GPU.

 

Some sort of audio register could also be implemented which means the MK2 can be used to produce and mix 16-bit audio into the HDMI signal. On-board sound synthesis and sample playback anyone? :-)

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Very nice! Having the extra vram for 80 column/text2 mode could be very beneficial for the programs that are too difficult to modify. If you allow for the blink attribute, even better.

 

V9938 potential aside, it seems to me the most important achievements are the updated electronics, reduced size, extra memory, and the more current video output method.

 

Thanks for spilling the beans!

 

If code was going to be added to bring it up to V9938, take it all the way to the V9958.

 

V9938 software to my knowledge is fully compatible with the V9958, and you get a bit of a boost in video graphic capabilities as I recall.

 

Beery

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If code was going to be added to bring it up to V9938, take it all the way to the V9958.

 

V9938 software to my knowledge is fully compatible with the V9958, and you get a bit of a boost in video graphic capabilities as I recall.

 

Beery

Don't you lose the mouse, as well as something else though. I think a selectable logic would be great. Take it to 9938 or 58 as the needs dictate. My 'two cents'. :)

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On a unit with a real 9938 that has the extra hardware for the mouse, yes, you would lose it. I did not see indication the MK2 brought out anything to use a mouse in the future.

 

Beery

You are probably right, but I was thinking that if it could emulate a 9938, that with a daughter board( would have to have something to fit the MK2 to the physical 9938 pinout on say, a Geneve, then the mouse stuff could be added.

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You are probably right, but I was thinking that if it could emulate a 9938, that with a daughter board( would have to have something to fit the MK2 to the physical 9938 pinout on say, a Geneve, then the mouse stuff could be added.

 

Hmmm, I see your point. Was not thinking so much about a Geneve upgrade as I was thinking of the TI-99/4A upgrade route. Still though, those mouse support going from an original 9918 device to a 9938/9958 device in our world would be very limited to a specific and very small Geneve user base.

 

On the other hand, if it were an upgrade from the Yamaho V9938 to a "super" V9938, then any of those devices that had been built with a 9938 would be able to use the mouse support if those devices had the other hardware designed into them. Myself, I am not familiar with other non Geneve 9938 hardware to know if there is market demand.

 

Beery

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I registered just to give a note of caution:

HDMI is regulated by HDMI Licensing, LLC. They're kinda lame. And when I say kinda lame, what I mean is "you wish you'd picked a fight with the Russian mob instead."

The license fee is $10,000 to per year, plus $0.15c per unit.

They will go after your home, your car, everything you own. They seem to get great delight in going after hobbyists.

They will utterly destroy your life if you release a product with an HDMI, mini HDMI or micro-HDMI connector on it.

In my designs I use a non-HDMI connector, then supply a licensed HDMI cable that has been modified. DVI is HDMI minus DHCP, but the standard connector is too bulky.

Good luck!

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