MEGA65 FORUM

What will be the max amount of RAM ?

append delete adtbm

Hello,
first of all: I love this project !

second: the Pictures of the prototype are amazing !!! But...

...unfortunately, some people believe (not me) that the C65 you are showing is actually a real one, not your prototype, so i think it would be helpfull to show the people the nexys & widgetboard inside as well.

Now to my main question:
gathering all the available information together. The Original C65 was capable to be upgraded via the bottom expansion slot to a max of 8MB RAM. i think it should have worked via Bank switching and the DMAGIC should have done the trick. Are you planning to to use the same amount of RAM and the same way to access it. The Base RAM was 128KB.
This is the amount that you have put down for the Specs of the Mega65 as well. I think i have read something that you are trying to access DDR ram. Is this true ? What are your plans ? Will there be 8MB Bank switchable RAM ?Same quetion is on your facebook page.

Thank you very much !

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append delete #1. Meshuggah333

The system comes with 128MB of RAM, more than enough for anybody doing programs for the machine IMHO.
IIRC there will be a trap door under the MEGA65 for expansion, so even more RAM is possible I guess, maybe we'll see some crazy expansions with a second FPGA and/or crazy sound/graphic chips, etc... or maybe not :)

:: @Meshuggah333 added on 24 Mar ’16 · 12:02

Just checked the specs, the GS4510 CPU has a 28bits address bus, so that's a max of 256MB RAM (I don't know if there's reserved memory space for peripherals and the like, so don't quote me on that). Not bad for an 8 bits CPU :D

append delete #2. gardners

We are indeed intending to allow the use of 128MB or more of DDR type RAM as the bulk memory expansion.

The machine also already has 256KB of RAM, of which 128KB is used for the "ROM", but can infact be used as a 2nd 128KB of RAM -- the only problem is that the VIC can't see it, so it is a bit like 128KB chip RAM, and 128KB fast RAM, if we use Amiga terminology.

This comes back to a final point: on a real C65, the mostly non-existant RAM expansion boards allow the expansion RAM to be used by the VIC, by changing which 128KB it can see. We can't currently do that, and might not ever, because DDR RAM has horrible latency, which makes it really hard to make available in a way that the VIC-IV can see. It certainly isn't something that we will be worrying about for the first release.

append delete #3. Deft

First, regarding the "fake" prototype, this is super funny. I could just point you towards the few errors that still exist in the prototype housing (I have avoided to show them when making the photos but they still can be seen) but that would be too easy - find them yourselves! *evil laughter*

Second, this scond prototype has a new original C= keyboard and a new replica C65 mainboard, so no, there is no devboard inside. This replica mainboard also has some very tiny differences to the original mainboards besides it is missing all the C65-specific custom chips.

People have actually seen, touched and opened that 2nd prototype at Retrofair Spring 2016 in Mannheim Germany so I am not discussing whether I am lying or not ;)

This said, next bunch of photos will probably be beauty shots of our own mainboard and the *modified* final case, which will have more ports than the original.

Until then, keep up the conspiracy theories :D

append delete #4. LoveMega65

W..w....wait...are you saying the final release of Mega65 will have it's own motherboard not the Nexyy thingie miggic???!!

(stands up and dances)

append delete #5. Solei

Go̦̤dâ̘̝͚͙͐̈́̂̒́͘͢ͅm̻͈̗ͅmi͗͗t Deft, now you're teasing us too much. we wanna see that mainboard like,
....right now ;)

append delete #6. adtbm

Hi Deft, thanks for your answers !

It wasn't me who didn't believe the pics. honestly ! I am following the development now for quite a while and i KNOW that these prototypes are real.
I was just posting, what i was reading in several other forums, after they have seen the pics.
Of course, i have tried to convince them...but try to tame a troll....

I hardly can't wait to get my own mega65 into my hands...

append delete #7. gardners

Actually, it looks like we might have 512MB of DDR3 RAM available on the final units (but this could change completely), and so the CPU will end up with 32-bit memory mapping space in the end. However, right now we still haven't implemented support for the DDR ram on the Nexys boards, because it is a bit of a pain, and not our highest priority. C65 Bitplanes and 6502 illegal opcodes are much more important that buckets of RAM.

append delete #8. Deft

To clear things up: The PCB inside prototype #2 is in fact a replica of the original c65 mainboard but we do not intend to make any of those (again, the custom chips are absolutely unavailable). It only has the function to demonstrate that we have reached the point where Commodore stopped the project so we can continue and improve it. Our own mainboard is still under heavy construction and will be different. I am willing to make photos of the prototype board and also the case with the last "problems" that have now been removed in the digital models if that helps to calm down the trolls. But don't forget a troll is a troll so there probably is no point... however if you want to try please send a message over mega65.org.

append delete #9. LGB

Maybe it's a silly question, but: I thought originally that the original nexys board will be used, connected to another board. Is it the plan? Or a really own board also replacing the devel FPGA board, and the FPGA etc themselves will be soldered on the very own and unique board of the Mega65?

append delete #10. MIRKOSOFT

Same Q: Will be possible simply connect any <bridge?> containing ports to Nexys4DDR? I'm using it mainly for M65, sometimes for Apple II, trying programming in VHDL... I need not retrostyle, but real functional M65, in case of keyboard very nice looks last published 87-key prototype.

Miro

append delete #11. gardners

At the moment we are planning to make a complete new motherboard as the preferred solution. This will allow more physical ports than when using only the Nexys4 boards. That said, we still intend to continue to support the Nexys4 board.

append delete #12. LoveMega65

I want the new motherboard :)

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