Changing JagGD cart speed to 2-cycle?

[Clint Thompson]

Thought I made a post about this somewhere a while back but can't seem to find it.

 

I'm coming back around to creating goodies on the Jag again but seem to find myself in a bit of funk. It appears the JagGD is forcing 5-cycle while the Skunk can do 2. (Someone correct me if I'm remembering this wrong but I'm pretty sure that's how it can play commercial ROMs fine by basically double-speeding the 16-bit cart width, no?) Which once again brings me to, can you or is there a way to force the GD into 2-cycle like that of the Skunk? I can't imagine the 16-bit Skunk having slower access than the JagGD.

 

Can you please confirm @SainT

 

Seems whatever the GD is doing it automatically overrides my code to 5-cycle regardless.

Edited July 20, 2022 by Clint Thompson

[SainT]

The JagGD cannot do faster bus access, it uses standard 10 cycle / 32bit (commercial ROM) access. The reason the skunk uses 5 cycle is because it uses a 16bit bus, therefore operating theoretically at the same speed as the 10 cycle 32bit access.

[Cyprian]

2 hours ago, SainT said:

The JagGD cannot do faster bus access, it uses standard 10 cycle / 32bit (commercial ROM) access.

just for clarification, 10 cycles 26MHz?

[SainT]

 

This is related to TOM cycles, so ~26Mhz, yes.

[Cyprian]

ok

[Clint Thompson]

Thank you for clarifying. 

On 7/20/2022 at 2:32 AM, SainT said:

The JagGD cannot do faster bus access, it uses standard 10 cycle / 32bit (commercial ROM) access. The reason the skunk uses 5 cycle is because it uses a 16bit bus, therefore operating theoretically at the same speed as the 10 cycle 32bit access.

 

[DEATH]

To be exact the skunkboard runs faster than a classic ROM at 10cycles because there are many accesses that can be done in 16bit (notably by the 68000, or Jerry why not). In fact, 16bit accesses are done in 5 cycles with the skunkboard while they remain in 10 cycles for a normal ROM.
It seems to me that there is a video showing Doom running on a ROM and the other on the Skunboard and there is a noticeable difference in speed.

 

Edited January 8, 2023 by DEATH