Parker Bros card with different banks scheme? A2600

[Thomas Jentzsch]

Thanks for the explanation. That seems to fit to the existing ROM's code.

 

Since the ROMs are 1:1 conversions from Parker's E0 bankswitching, they always switch only one segment.

[alex_79]

Yes, I can't imagine that "feature" to have any practical use. I think it's simply the result of this specific board design, and the code is supposed to only set either A4 or A5 or A6 to zero when bankswitching.

[Thomas Jentzsch]

I suppose this was cheaper to build than the original Parker scheme?

[alex_79]

I imagine it to be the case, although I don't know how the scheme was implemented in the original PB games.

 

[Thomas Jentzsch]

AtariProtos.com has a prototype board picture.

[alex_79]

Thanks. That proto uses 5 ICs compared to 4 in the board shown in this thread, so I guess it's a bit more complex and expensive to build.

[Thomas Jentzsch]

12 hours ago, alex_79 said:

Thanks. That proto uses 5 ICs compared to 4 in the board shown in this thread, so I guess it's a bit more complex and expensive to build.

And two of the 5 ICs might be more complex, no? They have 20 instead of 16 pins.

 

Here is another board, that looks pretty simple. Or is the IC something more expensive? Or maybe this early demo is only 4K?

Edited April 11, 2022 by Thomas Jentzsch

[alex_79]

1 hour ago, Thomas Jentzsch said:

And two of the 5 ICs might be more complex, no? They have 20 instead of 16 pins.

Yes, I think that larger ICs would typically be more complex and cost more, although the availability probably plays a role on the price too (Common parts are cheaper). I'm no expert, though.

 

1 hour ago, Thomas Jentzsch said:

Here is another board, that looks pretty simple. Or is the IC something more expensive? Or maybe this early demo is only 4K?

The latter. The 24 pin EPROM is 4K. The 74LS04 is an inverter used to invert A12, as EPROMs usually have an active low "Chip Enable" pin.

[alex_79]

I drawn a (hopefully correct) schematic of the Bankswitching logic found in the board shown in this thread:

schem_PB_Brazil.pdf

[Thomas Jentzsch]

Cool! Thanks!

 

@cetics (whenever you should come online again ) Do we know the brand which was using this board?

 

BTW: The two games are Montezuma's Revenge (01.bin) and Popeye (02.bin) (both 100% identical to the NTSC releases, except for the hotspots). Atarimania has no 2 in 1 with these two games listed.

Edited April 11, 2022 by Thomas Jentzsch

[cetics]

Thanks for the answers. I think I still have the cartridge in my collection, but it never worked, so I was afraid to invest and ask for a PCB to be manufactured in China. Because I wasn't sure if the dumps were good. I found a similar board (working) on the Brazilian market a while ago and thought I'd buy it to see what was wrong with mine, and try to export the working schematic. But the price they asked was simply impossible to pay back then. Today I looked and couldn't find it anymore. I'm thinking of redesigning the board and ordering a PCB in China for testing.

[cetics]

Fotos e DIP.zip

Here are the photos of the board I made at the time and an attempt to redraw the board in dip trace (with source file). It may be necessary to check as I may have made some mistake (no tests)

[cetics]

In this video (52:12) the owner of the channel shows a similar board working.

[Thomas Jentzsch]

Support for these ROMs will be added (as "03E0") with the next Stella release.

[xangel]

Catch my files - they are correct and were tested. Eagle CAD needed to open.

In this project I was using 39SF010 because I was thinking I would be able to put all E0 roms there. But unfortunately this cart uses different "hotspot" so we have only two games

 

So You can change 39SF010 to smaller and cheap 27C256 and You don't need rotary switch - You can use two-position switch for two games.

It fits to Sikor's plastic cases.

Probably edge connector should be 3mm shorter, because when it is so long it will not open trapdor in some Atari consoles (fat).

 

And pay attention to R1 resistor (1k). Not works without it. Probably new TTL chips don't like floating pins.

2600 Sikor E0.brd 2600 Sikor E0.sch

Edited April 18 by xangel

[Pilot99]

Nice! do you used the original roms posted by Cetics without any modifications?

[Pilot99]

On 4/18/2024 at 2:30 PM, xangel said:

Catch my files - they are correct and were tested. Eagle CAD needed to open.

In this project I was using 39SF010 because I was thinking I would be able to put all E0 roms there. But unfortunately this cart uses different "hotspot" so we have only two games

 

So You can change 39SF010 to smaller and cheap 27C256 and You don't need rotary switch - You can use two-position switch for two games.

It fits to Sikor's plastic cases.

Probably edge connector should be 3mm shorter, because when it is so long it will not open trapdor in some Atari consoles (fat).

 

And pay attention to R1 resistor (1k). Not works without it. Probably new TTL chips don't like floating points

 

Xangel, what you did in the RN2 4k7 area? Tryed to see on the PIC of the board but I can't see any resistor there.  You used a resistor network or there is a wire connecting ALL the 9 pins together?