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Lynx Multi Cart


SainT

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Well, that was an interesting evening of debugging! As far as I can tell the programming side of things is working really nicely after a fair bit of debugging. Reads the image from the memory card and programs the SRAM fine. Now the pisser is that I thought I was being clever by powering the 4040 counter which I use to generate the low 11 bits of the address (just like the Lynx itself) with the 3.3v regulator. I assumed if the IC was not powered (I turn off the 3.3v reg after programming) then it would not interfere with the signals still connected to its output pins.

 

This doesn't appear to be the case. As soon as the Lynx bus is activated, the 5v applied to the counter output pins actually appears to be powering the chip?! Really weird. The upshot is either adding another 245 like chip to isolate the counter or find a counter with chip select (which I couldn't before, I did look!).

 

On the plus side, most things are working... :)

Edited by SainT
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Usually having higher voltage on the pins than on the VCC destroys the chip. Perhaps they have protecting diodes that pass the overvoltage from the inputs to VCC to protect the chip. That would explain why it gets powered up.

 

In any case congrats to get it this far.

 

--

Karri

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It's a high voltage tolerant 4040, but apparently due to the diode arrangement on the output stage if the voltage is higher on the output pin than vcc this gets fed through to the power rail. Oh well, something I've learnt!

 

I'm pleased with the progress though, this would appear to be very close to actually working. I'm going to switch the 4040 for a couple of tristate 8 bit counters cascaded together and that should fix the problem. It does mean getting new pcb's made up and the inevitable wait as they come over from china, though... ah well!

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There will be a way to save stuff to the memory card, but the game will have to be modified to support this. Not a trivial job, but someone with good knowledge of the Lynx should be able to do this. My main concern is supporting the library of commercial games out there, none of which use saves, niceties like game-saves for existing games will have to be provided by the community.

 

Also any games made in the future can make use of the extra features of this card like accessing the memory card directly for effectively infinite sized roms and save data.

Edited by SainT
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The real question is, (not taking away from the flashcard's worth), would that be a viable option for Lynx games to be sold? I mean, is anything like a very high price keeping devs from creating game cards that use some flash memory or even cheap run-of-the-mill SD cads instead of ROM chips?

 

Functionality would be no different for the player than playing on the flashcard, but dedicated fans like to have physical releases of games, so I think that the flashcard technology of having access to huge amounts of memory cheaply available at any electronics shop could be viable for single game releases as well.

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People can make carts themselves if they want, sure. If it's just a flash rom and a small eeprom then it'll be cheaper than all the stuff on my card. This is just a convenient way to play the whole Lynx back catalogue on one cartridge, it just also happens to give additional functionality for new titles should people be interested in using it.

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I changed the address counter used for programming from a 4040 to 2 x 590's cascaded together and re-layed out the board tonight. The 590 has a separate output enable so I can disable them when I hand over the bus to the Lynx.

 

I'll do one final check over tomorrow, then its time to get another batch of boards ordered. :)

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I believe that this could open up the Lynx to new kind of programming. You could generate streamed landscapes where trees and and monsters get in memory while you approach them. Also unlimited space for sounds and music would be great.

 

But the application that is most needed is the Desktop for the Lynx. If the SD can contain a library of games we need a way to run them from the card. This means a need for some kind of Desktop. In MegaPak 1 the Desktop mimics PSP. Should this look like Windows 8 or some kind of MAME frontend with animated icons for each game.

 

This is not really in Lynx resolutions:

post-2099-0-88329300-1414129609_thumb.jpg

 

Or like PSVita:

post-2099-0-26415000-1414129849_thumb.jpg

 

Or like MegaPak 1:

post-2099-0-43865200-1414130052_thumb.png

 

The games could also be identified by some kind of small hash. So that every game on the SD could automatically find the right animation on the Desktop.

 

Or is the SD accessed by file names? Who knows...

 

In any case this is a most interesting new toy for the Lynx community :)

Edited by karri
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Yeah, the next step after getting a ROM running is the game selector. I was thinking to update the Lynx ROM images and create a new file format which contains an icon for the game potentially with screenshot or something so you can pick the game via icon from the Lynx. I think something like the cross media bar from the original PSP or PS3 could be good -- there's potential for save game management as well if that's useful. I'm not a fan of the Vita's interface. ;)

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I actually implemented the cross media bar in MegaPak vol1. The sections were:

 

Setup - Backgrounds - Jukebox - Games

 

The columns were:

 

Setup

- EEPROM

- ComLynx baud rate

- Color scheme

 

Backgrounds had

- lots of pictures to choose from

 

Jukebox had

- lots of tunes

- you got Lynx-coins from finishing games that you could use to buy more tunes. Not all tunes were "free".

 

Games had

- lots of minigames

- plus a hidden game that you could unlock by finishing some other games first. (A Scott Adams adventure by permission of Scott Adams himself)

 

If you want I can extract the sources for MegaPak vol1 cross media selector so that you have some frame to start building on.

 

It is written in cc65.

 

About the header format...

 

I kind of like the idea to change the background to a full screen taken from the game when you move your selection over the games name. That would also be simple to implement. We could re-map all the screens to the default palette to avoid color clashes and flickering.

 

Another good thing is that you don't need lots of artistic talent like you would if you create icons.

 

A simple implementation would be to prepend each image with a 160x102 literal sprite.

Edited by karri
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New layout tweaked and next batch of prototype PCB's ordered. Now to wait a fortnight. :sleep:

 

When I finally get this thing running ROM's I'll give you a shout Karri, perhaps you can give me a hand with the menu selection code. Been many years since I've played with Lynx code. :)

 

And on a different note, if anyone has a working or broken Lynx 1 they would like to donate to me for testing how well this cart fits in the Lynx 1 cart bay before I finalise PCB's for production, that would be appreciated. I've been keeping an eye out for one on eBay, but I don't wan't to pay much as I've already got a couple of Lynx 2's and have spent a fair bit of money on the PCB work so far. ;-)

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Thanks. I'd love help with the game launcher.

 

Do the interested parties have suggestions what it would look like?

 

My thoughts today would be like in MegaPak but when we highlight the game the background changes to a screenshot of the game.

 

All game would be in an alphabetic list.

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Thanks Karri. :)

 

One nice thing is that the menu will be loaded from the memory card just like any other ROM, so it can be upgraded or different menus created as people like... :D

 

Edit:

One thought on the menu side -- a few people have expressed interest in helping (LX.NET for one). It's worth setting up an opensource project or something so multiple people could collaborate and improve or even fork and have different menu types. I'll do a low level API for talking with the flash cart allowing you to load images from the memory card into the SRAM, then the menu code (or game) will just talk to that.

Edited by SainT
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Yeah, I've been toying with the idea of making it all opensource. Certainly all of the Lynx code will be (that I do anyway), but the schematics / layout and PIC firmware will remain closed initially. Once its all up and running I may open it all up... I've not decided yet.

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