Eprom Cartridge Rev 1.5

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Por Wierzbowsky

Guardian (3499)

Imagen del Wierzbowsky

09-10-2021, 01:06

To me it looks like the Gerber files generated from this project create a non-working cartridge board because the top layer's copper polygon overwrites most of the tracks that should go to important pins, CS_12 for example.

I created Gerbers and viewed them in a Gerber viewer of JLCPCB. And that's what I saw:

Does this look OK to you? To me it looks like a non-working cartridge board.

Do you still have unassembled boards? If yes, could you take a GOOD picture of the board from both sides? Then it will be clearly seen where the problem is.

Por SkalTura

Champion (360)

Imagen del SkalTura

09-10-2021, 09:09

Here is the cartridge schematic I have (old Elektor article).
I know for sure this one is working, made it many moons ago when I was just a little lad ;-)
MSX Eprom cartridge

Just check the connections between the PCB fingers and the Eprom pins, compared to the schematic in the article...

Por repetto74

Rookie (17)

Imagen del repetto74

09-10-2021, 11:58

Alexey wrote:

To me it looks like the Gerber files generated from this project create a non-working cartridge board because the top layer's copper polygon overwrites most of the tracks that should go to important pins, CS_12 for example.

I created Gerbers and viewed them in a Gerber viewer of JLCPCB. And that's what I saw:

Does this look OK to you? To me it looks like a non-working cartridge board.

Do you still have unassembled boards? If yes, could you take a GOOD picture of the board from both sides? Then it will be clearly seen where the problem is.

Here are the pictures and indeed some of those jumper settings are not connected (all to GND).

Por Wierzbowsky

Guardian (3499)

Imagen del Wierzbowsky

09-10-2021, 20:16

Yep, as I suspected, this board can go to trash. You are lucky you didn't set any other jumpers or you could have had a short circuit. I can offer you a few SGC boards designed by RBSC. Contact me if interested.

The SGC cartridge is reprogrammable if used with W27C512 EEPROM. I can also sell you the adapter (board+slot) for your EEPROM burner, so that you could reprogram your cartridge. The 65kb ROM image creation/conversion utility can be found here:

https://github.com/Wierzbowsky/SGC_ImageCreator

Por Wierzbowsky

Guardian (3499)

Imagen del Wierzbowsky

09-10-2021, 18:10

I've fixed the mess on the original board. That's how it should look like:

I can't share the project because the bloody EasyEDA doesn't allow me to do that. But I put Gerbers here:

https://podrezov.com/temp/Gerber_MSX_64kb_Cart_Fixed.zip

DISCLAIMER:
I just fixed the top layer's copper, bottom silkscreen and VIA sizes, but I didn't verify anything else. So you are using those Gerbers on your own risk.

DO NOT USE FOR COMMERCIAL PURPOSES!

Por repetto74

Rookie (17)

Imagen del repetto74

10-10-2021, 10:23

Alexey wrote:

I've fixed the mess on the original board. That's how it should look like:

I can't share the project because the bloody EasyEDA doesn't allow me to do that. But I put Gerbers here:

https://podrezov.com/temp/Gerber_MSX_64kb_Cart_Fixed.zip

DISCLAIMER:
I just fixed the top layer's copper, bottom silkscreen and VIA sizes, but I didn't verify anything else. So you are using those Gerbers on your own risk.

DO NOT USE FOR COMMERCIAL PURPOSES!

Thank you Alexey :D :D . I have already ordered a working PCB from the 8bitManshed. Glad that you are sharing the fixed version of this bad design ;) . I may source the pcb again and give it a try to have a spare in the future LOL!

Por capsule5000

Master (156)

Imagen del capsule5000

11-10-2021, 02:11

Hello good afternoon Alexey. This board is very interesting, but you know how jumpers work??

Por Wierzbowsky

Guardian (3499)

Imagen del Wierzbowsky

11-10-2021, 15:18

capsule5000 wrote:

Hello good afternoon Alexey. This board is very interesting, but you know how jumpers work??

It's not my board, but I know how these boards generally work because I designed the SGC cartridge. This board is designed for 27C128 (16kb), 27C256 (32kb) or 27C512 (64kb) EPROMs. By RD or CS jumpers you control the size and the location of the ROM in the MSX slot. By connecting of P27 and P1 to power, ground or address lines you can either use the full chip's address space or select 32kb or 16kb pages in it. For example you can put one 64 or 49kb game, two 32kb games or four 16kb games into this cartridge. This is only for simple games that don't use mapper.

Addressing and size in MSX slot:
RD=0x0000-0xFFFF, 64kb;
CS1=0x4000-0x7FFF, 16kb
CS2=0x8000-0xBFFF, 16kb
CS12=0x4000-0xBFFF, 32kb;

Address space/page selection:
P1=selects first or second 32kb of the 27C512 chip; if connected to A15, then the full 64kb can be used
P27=select first or second 16kb of 27C256 chip; if connected to A14, then the full 32kb can be used
If 27C128 chip is used, the P1 and P27 should be connected to power

I am not sure what happens if P27 is connected to A15 instead of A14. All the above describes how the properly designed cartridge should work, but I didn't thoroughly check this cartridge's design. If you want to have a cheap and simple reprogrammable cartridge that is verified to work, then SGC is your choice. Otherwise just buy Carnivore2, MFR or FlashJacks and enjoy having multiple games, sound cards, disk drives and extra RAM in a single cartridge.

Por repetto74

Rookie (17)

Imagen del repetto74

31-10-2021, 17:51

Hi Guys,

Coming back to you with this eprom cart issue I had on this thread. I have received the pcb from 8bit manshed, mounted it and burned a 27c256 with Goonies binary to test. Well, that does not work for me. My HX-10 will boot straight into the prompt and not from the cart slot.

Continuity check of solder joints is ok, jumper have been set accordingly to use a 27c256. Wondering now if I did not break the cart slot when testing the faulty pcb (shorted out something). oO

Por repetto74

Rookie (17)

Imagen del repetto74

02-11-2021, 16:54

Nope. I tried with another 27c256 eprom burned with the testram binary and another with the MSXDiag but no luck. Cannot start any program from the cart slot. Any idea where to troubleshoot? oO oO

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