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SainT

Lynx Multi Cart

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You probably already know this, but pin 31 and 33 of the cartridge port have to be connected for the device to power on. It might be a way to shut it down (poor mans reset, where the user has to turn the device on again). Not sure what happens if you briefly disconnect it.

 

Also, there is a register in the Lynx (Sysctl1) that might be able to turn off the device programmatically from the 6502code running.

Hope this helps.

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Yeah, you will be able to load as many ROM images as you can fit on an memory card. So certainly every Lynx game ever made. The only issue will be sorting out the different ways of accessing 1MB images and save game information as there was no standard method of doing this.

 

I've given some thought to powering off the Lynx via the cartridge pins, but I'm pretty sure that it wont work. As soon as you lose power I believe you have to power it back on again.

 

So I have another cunning plan to get around it. :)

Edited by SainT

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On 6/26/2014 at 3:41 PM, Bill Loguidice said:

 

I'm interested in both the Enterprise upgrades, as well as the Lynx SD card.

 

Internal 512KB RAM expansion is £20 plus postage (installation instructions) if you want one! :) Still haven't finalised price on the memory card interface, although I do have working hardware. Just need to sort out some manufacture issues.

Edited by SainT

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I'm interested too if the price is right.

 

If possible you should make sure the flashcard is prepared to load games beyond 512 Kilobyte. Seeing how far Game Gear and Game Boy got I think that hombrewers will have to use more memory in the future for ambitious projects. :)

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Yeah, no idea about price yet, depends on how clever I can be. We'll see.

 

In terms of cart size, the Lynx will be able to communicate with the card, so you could effectively have the whole memory card at your disposal for homebrew.

Edited by SainT

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Internal 512KB RAM expansion is £20 plus postage (installation instructions) if you want one! :) Still haven't finalised price on the SD interface, although I do have working hardware. Just need to sort out some manufacture issues.

 

That's awesome, but my technical skills are not up to snuff. Considering how expensive it is to acquire an Enterprise, I'd rather not risk doing the work on mine (and yes, I know this is relatively straightforward, just not for me). Will the SD card interface require any internal modifications?

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On 6/26/2014 at 4:55 PM, Bill Loguidice said:

 

That's awesome, but my technical skills are not up to snuff. Considering how expensive it is to acquire an Enterprise, I'd rather not risk doing the work on mine (and yes, I know this is relatively straightforward, just not for me). Will the SD card interface require any internal modifications?

 

Nope, the memory card interface is plug and play! At it also includes 512KB RAM as well as 512KB FLASH expansion as well. If you have both plugged in you get 1088KB of RAM. I have done 1MB versions of the internal expansion too. Some nutters (mostly in Hungary) have some really souped up machines overclocked to 7MHz with a couple of megs of RAM. Old hardware is fun. :)

Edited by SainT
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Nope, the SD interface is plug and play! At it also includes 512KB RAM as well as 512KB FLASH expansion as well. If you have both plugged in you get 1088KB of RAM. I have done 1MB versions of the internal expansion too. Some nutters (mostly in Hungary) have some really souped up machines overclocked to 7MHz with a couple of megs of RAM. Old hardware is fun. :)

 

That is wonderful news! I'll definitely buy that when it's ready. 512KB is plenty for me! Good luck on all the projects.

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If you're serious about this then I think it's safe to work on the assumption that everyone here will buy one! What time scale are you allocating for this project? I really hope this can come to fruition as quick as is reasonable. The replacement lynx screen project has nearly been ongoing for two years for example.

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I've looked at this and got a draft design in my head. The only problem I can think of is how you force a reboot of the Lynx in order to boot from the selected cart. Ie. my design is to have a 'selection' rom that interfaces the lynx to a microcontroller, and the microcontroller sends has an io buffer area which allows the rom running on the lynx to nav SD file structure to select ROM. Then have a command code to copy ROM from SD to SRAM or EEPROM, and have something disable the selection rom with high impedance, connect the game ROM, and force a reboot. Just not sure if it's possible to force that reboot without a power cycle. It's the reboot that is the sticking point IMO.

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You probably already know this, but pin 31 and 33 of the cartridge port have to be connected for the device to power on. It might be a way to shut it down (poor mans reset, where the user has to turn the device on again). Not sure what happens if you briefly disconnect it.

 

Also, there is a register in the Lynx (Sysctl1) that might be able to turn off the device programmatically from the 6502code running.

Hope this helps.

I think I've tried that register, and I think it just powers the Lynx off. =\

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On 6/26/2014 at 9:16 PM, GadgetUK said:

I've looked at this and got a draft design in my head. The only problem I can think of is how you force a reboot of the Lynx in order to boot from the selected cart. Ie. my design is to have a 'selection' rom that interfaces the lynx to a microcontroller, and the microcontroller sends has an io buffer area which allows the rom running on the lynx to nav SD file structure to select ROM. Then have a command code to copy ROM from SD to SRAM or EEPROM, and have something disable the selection rom with high impedance, connect the game ROM, and force a reboot. Just not sure if it's possible to force that reboot without a power cycle. It's the reboot that is the sticking point IMO.

 

 

The biggest problem with that setup with SRAM, micro and memory card is how you get the bootstrap rom image into the SRAM quick enough for the lynx to start reading it. Ideally you'd hold the lynx in reset and load the ROM into SRAM then release it, but we cant do this. And you cant power the lynx on and off at will either, as the power is controlled by the soft on / off and a signal from Mikey.

 

If you went that route you'd need a boot ROM and SRAM and switch between using a mux or something to switch the chipselect line. So all a bit messy.

 

I have a cunning plan to get around all this... just thinking it through. ;)

 

Oh and to reboot from software I believe you can just jump to FF80 with the Lynx ROM paged in.

Edited by SainT
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If you're serious about this then I think it's safe to work on the assumption that everyone here will buy one! What time scale are you allocating for this project? I really hope this can come to fruition as quick as is reasonable. The replacement lynx screen project has nearly been ongoing for two years for example.

 

Serious, yes, timescale, no idea. :) More like a couple of months than a couple of years, though.

 

I just do this sort of thing for fun as I like the challenge, however I don't have much in the way of spare time as I have a couple of young kids and a job. I've done a couple of projects like this already, however, so I feel quite confident in achieving it.

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A couple of months would be fantastic! Fully understand your time constraints. I wonder if you could make it compatible with both lynx models.

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I'm interested. I'm assuming MicroSD-based. But would you require another CPU and RAM like the AtariMax carts?

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Serious, yes, timescale, no idea. :) More like a couple of months than a couple of years, though.

 

I just do this sort of thing for fun as I like the challenge, however I don't have much in the way of spare time as I have a couple of young kids and a job. I've done a couple of projects like this already, however, so I feel quite confident in achieving it.

 

Well I hope you can handle the initial demand! Also, have you given thought to ease of inserting/extracting the cart from the Lynx I or II without damaging?

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Well I hope you can handle the initial demand! Also, have you given thought to ease of inserting/extracting the cart from the Lynx I or II without damaging?

 

I have other "homebrew" type carts for the Lynx like the BLL devkit loader (that was a long time ago!) and SIMIS which use just straight square edge PCB and they seem to work fine. Ideally the PCB could do with a chamfer on the mating edge, though.

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I'm interested. I'm assuming MicroSD-based. But would you require another CPU and RAM like the AtariMax carts?

 

Yeah, most likely the same as that.

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If I can get the fixerupper Lynx that I'm receiving to work, then I'm interested in getting one.

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Had a bit of time to do some messing with the Lynx and the time between successive reads is too quick (about 1.1 microseconds) to be clever about it any try and stream the data directly from the memory card to the Lynx. So I've given up on that train of thought.

 

I've also checked the boot sequence and you can happily cover a load of address / data lines on the cart with a bit of paper and turn the Lynx on and you get "Insert Game". If you remove the bit of paper the game then loads. So this sorts my bootup issue, just isolate the Lynx bus from the SRAM with some bus transceivers and program the SRAM with the micro, then allow the Lynx access to the SRAM when done.

 

So next it's down to picking a microcontroller.

Edited by SainT
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