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SainT

Upcoming Jaguar SD Cartridge

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On 8/1/2019 at 11:14 AM, SainT said:

 

A 16MB version is also possible with the JagSD.... ;)

How it's that possible? The 68000 can address 16MB and you need to reserve some address for cartridge and devices. If it's some kind of bank switching the limit can be much higher.

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On 7/31/2019 at 3:47 PM, CyranoJ said:

 

A part of me wants this to be the startup of the JagSD card, like a real ROM in it of this thing that always welcomes you, even better if it can be the animated background of the menu.

It'll drive people nuts but hey .... JagPowa.

 

 

Note: I really dig the Bad Apple video on all the consoles/old-computer it showed up .... catchy music!

 

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On 8/1/2019 at 7:46 PM, CyranoJ said:

As said above, when they are required, they will be made available..

 

It has not been an insignificant amount of work retro-fixing (pun intended) over 30 ROMs, and not something that was required to be done so forgive me for ignoring any and all self-entitled requests demanding them (not that this was one) - but while the device is not available I don't see any point in posting them at the current time. 

 

When Saint is ready, these will be ready.

Image result for rainman meme

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On 8/2/2019 at 2:54 PM, swapd0 said:

How it's that possible? The 68000 can address 16MB and you need to reserve some address for cartridge and devices. If it's some kind of bank switching the limit can be much higher.

 

You already gave the answer, bank-switching is the key which enables nearly unlimited space.

According the the documentation, the first 4MB ($000000 - $3FFFFF) is RAM bank one (only 2MB used on the Jaguar), the second 4MB ($400000 - $7FFFFF) is RAM bank two (not used on the Jaguar), then there is 6MB ($800000 - $DFFFFF) reserved for cartridge rom. The last 2MB ($E00000 - $FFFFFF) is reserved for boot ROM (128KB used in the Jaguar) but an 128KB windows in that area ($F00000 - $F20000) is for the TOM & Jerry registers and local RAM.

 

So in the 6MB cartridge space you could think of several different bank-switching layouts like 4 banks of 4MB or a single fixed bank of 4MB and the second 2MB spaced bank-switched with 6 banks of 2MB (12MB). I do not know what bank-switch layout Saint used but as the CPLD used is reprogrammable, you could create every bank-switch layout you can think of.

 

Also the cartridge port seems to expose 24 address lines, so in theory you could even use addresses that are normally reserved for RAM or unused IO space or unused boot ROM space. But this might interfere with the RAM interface if that still returns (random or mirrored) data even when there is no RAM.

 

Robert

 

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17 hours ago, rdemming said:

I do not know what bank-switch layout Saint used

Any of the 6x1MB banks at $800000-$D00000) can point to any of the 16 available banks in the SD "cart rom" - it is glorious :)

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1 hour ago, CyranoJ said:

Any of the 6x1MB banks at $800000-$D00000) can point to any of the 16 available banks in the SD "cart rom" - it is glorious :)

Well thats cool. How fast is accessing that vs main system memory?

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8 minutes ago, zezba9000 said:

Well thats cool. How fast is accessing that vs main system memory?

 Same speed as rom

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1 hour ago, SCPCD said:

and RAM is 2 cycle and ROM is 5 cycles min.

ROM is always 10 cycle for JagSD use (ie. standard commercial game spec).

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7 hours ago, SainT said:

ROM is always 10 cycle for JagSD use (ie. standard commercial game spec).

This is a hardware constraint or it can be lowered by software?, maybe it can be nice to have 1 cycle access time and put textures there instead of RAM.

 

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1 cycle isn't possible ; the speeds supported by the hardware are 2, 5, 6, 8 and 10 cycles. And 2 cycles is partially broken. Support for 5 cycles would be nice to give a speed boost to JagSD-only games.

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3 hours ago, Zerosquare said:

1 cycle isn't possible ; the speeds supported by the hardware are 2, 5, 6, 8 and 10 cycles. And 2 cycles is partially broken. Support for 5 cycles would be nice to give a speed boost to JagSD-only games.

OMG, do you mean that the Jaguar has hardware bugs? 😂

Edited by swapd0
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6 minutes ago, swapd0 said:

OMG, do you mean that the Jaguar has hardware bugs? 😂

Nope!

 

;-)

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8 hours ago, Zerosquare said:

1 cycle isn't possible ; the speeds supported by the hardware are 2, 5, 6, 8 and 10 cycles. And 2 cycles is partially broken. Support for 5 cycles would be nice to give a speed boost to JagSD-only games.

I don't believe it's possible, its pushing it a bit at 10. I'm using SDRAM, so there is some latency in random reads -- it's better suited for burst reads. Plus you have the refresh cycles to take into account for latency and the fact memory access is asynchronous, so there's no waiting for the cart ROM to return the correct value. You either get it there in time, or everything dies.

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12 hours ago, SainT said:

I don't believe it's possible, its pushing it a bit at 10. I'm using SDRAM, so there is some latency in random reads -- it's better suited for burst reads. Plus you have the refresh cycles to take into account for latency and the fact memory access is asynchronous, so there's no waiting for the cart ROM to return the correct value. You either get it there in time, or everything dies. 

Oh, the JagSD does not support 5 cycles rom access ? You did not test it?

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21 hours ago, SainT said:

I don't believe it's possible, its pushing it a bit at 10. I'm using SDRAM, so there is some latency in random reads -- it's better suited for burst reads. Plus you have the refresh cycles to take into account for latency and the fact memory access is asynchronous, so there's no waiting for the cart ROM to return the correct value. You either get it there in time, or everything dies.

That's unacceptable. I demand to get my money back!

 

 

Wait...

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9 hours ago, DEATH said:

Oh, the JagSD does not support 5 cycles rom access ? You did not test it?

Everything we have tested (and, believe me, that is a LOT) has worked.

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7 minutes ago, CyranoJ said:

Everything we have tested (and, believe me, that is a LOT) has worked.

Yes, it's my old mantra of supporting the software which exists, not the software that doesn't. It really helps to cut down the workload! :)

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11 hours ago, SainT said:

Yes, it's my old mantra of supporting the software which exists, not the software that doesn't. It really helps to cut down the workload! :)

It's like I was always told as a software developer - solve the problems you have, not the problems you don't have. ;-)

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A much enhanced version shall be waiting for you to test your shiney new SD cart with :)

 

320x200x4bpp + 21.9Khz 16 bit ADPCM audio
 

 

Video shows upload speed over USB

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15 minutes ago, LianneJaguar64 said:

Whoa, not reading through 97 pages... Can I get the cliffs notes version? 😁

Sure. There's an upcoming Jaguar SD cartridge.

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3 hours ago, madman said:

Sure. There's an upcoming Jaguar SD cartridge.

And there's no pre-order list, nor will there be one.

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