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Topics - michel_iwaniec

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EverDrive N8 / How do the map_cfg bits map to iNES header flags?
« on: February 03, 2018, 09:03 PM »
I'm trying to implement mapper30 support on the Everdrive N8, as a "Hello world" project to start off my mapper development ambitions - and give people the opportunity to run roms like Troll Burner on an Everdrive. It's pretty much a straight copy-n-paste of the mapper2 example provided by Krikzz, so not much complication getting the basic functionality working.

But I am running into trouble with my "stretch goal" to supporting both variants:
1) The original mapper30, which can be hardwired for either vertical/horizontal mirroring or single-screen mirroring
2) The infinitelives variation, which replaces all of that with 4-screen mirroring (using the last 8kB of the 32kB CHR-RAM for 4-screen mirroring)

The current proposal on nesdev for how to support both of these variants in one mapper number is to re-interpret bit3,bit0 (4-screen flag, mirroring-flag) of byte 6 in the iNES header as follows:
00: horizontal mirroring
01: vertical mirroring
10: 4-screen mirroring
11: single-screen mirroring

(this is not yet implemented even in most emulators but discussed in this thread:

From the mapper examples, I was easily able to see that map_cfg[0] usually denotes mirroring control, but I have not found any definition of the rest of map_cfg's layout. And I'm not even 100% sure there is a 1-to-1 mapping between both the relevant iNES mirroring flags and the map_cfg register.

So at the moment, I can only create a mapper30 file that is hard-coded to either use map_cfg[0] for horizontal/vertical mirroring selection, or hard-coded to do 4-screen mirroring, which is a bit of a shame.

Could anyone tell me a bit about exactly how the map_cfg register maps to the iNES mirroring flags?

EverDrive N8 / How
« on: February 01, 2018, 03:00 AM »

I figured I would finally try some mapper development on the Everdrive N8. But it seems I am stuck at the very first stage: Obtaining the software.

Namely, I thought I would use the official "Quartus II web edition software" from Altera which I found here:

But to even be able to download the software, the website requires me to register an account. And when I try to do this, the form always errors saying "Sorry. An error occurred when creating your account. Please try again.", with no information on what particular field it is refusing to parse.

Would anyone here happen to know how to get past that broken web form? Or if there is any suitable alternative software that can create bitfiles for the CycloneII FPGA in the Everdrive N8?

// Michel

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