z64 and 64M SIMM
This is an old discussion originally published on the dextrose forum
z64 and 64M SIMM
ashitaka
For a Lark the other day I tried it cause I had a 64M SIMM sitting around. It has never been confirmed here that someone has actually done it, so I tried. It gives a memory error upon booting. So in case anyone was wondering it doensn't work.
_kid
I tried the same thing (with the same result) around one year ago.
Nobody seems to care... Every other month someone comes around with a
"new bios" that will really play 512M game.
ThanatosM
Yea but maybe the next one really will work......
Actually no it won't. It is clearly not possible to fix with software updates so how about you all forget about trying it. Stop flogging the damn horse. Stop kicking the Z when it is down. Just Stop. The Z64 is 256MBit and that is that. An end. This does not requite a response unless it is just a general message without point or reason, in which case I would have no time for it anyways. If anyone ever really get's it to work then yes I would be impressed, but until the next coming of the christ child I don't see this happening.
Oh yea hi _kid long time no see ;p
CoYoTe99
hehe.. 64mb ram in a Z.. Can't even find Pinout for the Processor.., let alone schematics on how to modify the Z..
Like ThanatosM Said, It ain't gonna happen
Darkflame
I wouldn't just dismiss the possibility of 64MB support in the z64 with an iron clad fist...Given the right approach and skills, i'm sure it could be done...it's just no one got around to it yet...The only ones who could honestly say "no it couldn't be done" is the folks who designed the z64..but they're too busy swimming around in their pools of $$$ to take a minute to actually look into the situation...
CrowTRobo
Actually, back when 512mbits first appeared and this whole thing began, Harrison actually said on this forum that the Z64 couldn't support anything higher than 256mbits without another hardware version.
_kid
Even if you found that (and in fact it's easy) you'd discover that the ram of the cart emulator is not part of the address space of the Z64 CPU...
_kid
It's quite easy to dismiss that:
first, in theory, if the Z64 was able to take advantage of the larger column of a 64M simm, it would be, without a bios update, atleast able to use the first 32M, and it does not.
second, it is relatively easy to prove that the Z64 is not actually able to correctly refresh a memory larger than 32M, being the DRAM refresh part of the asic that performs all the cart emulation related functions, and being that device an OTP part, no bios will be EVER able to change this behavior.
of course you COULD add another 32M of the Z64 via a specially designed "CART" to use in place of the common boot cart. In that device you'd have to fit the "high" 32M decoding, refresh logic and (of course) either a passthru for a bootcart or a CIC+EEPROM. At that point all you'd need to do is modify the bios to use the extra space... This is feasible, but hardly worth the effort...
luna_securit
yeah so buy the carts you tight arsed bastards much cheaper
Mr.Mucho Romz
well said luna
/MMR
Darkflame
So as long as a external device could possibly be added to the cartridge port easily says that is could be possible for the z64 to support 512Mbit games...as long as there are ports accessing the cartridge and that a 512Mbit cart could be played using the original 512Mbit cart shows that the z64 addresses anything above 256Mbit from the cart proves my point....and _kid has the same thought I had, except I was thinking of something along the sides of an sram card....I have 2 32MB pcmcia sram cards and thought maybe it could be possible...who knows..
ss_forces
whats the bandwidth on sram? I don't know myself, but it can't be that of ram/rom
(whether it's still more than the n64's requirements i don't know either)
CoYoTe99
umm. The Processor Does Support 64mb Ram (in banks) .. Besides.. Where did you find the Pinout of the Processor? I looked Everywhere..
And like Luna Said..
5 games? I would rather just go buy them..
??hmm. Is that a PC/104 Bus I see on the mb?
I am Curious To see how the Z64 app access's the Cart & Lcd Screen. I have other SBC systems that I have played with. I was trying to Find a Way To connect a Display to the Z, (no reason for it, just for dev & playing with other apps.) However, the Z64.exe Runs on any PC.. Justs Beeps Like it was on the Z. But how does it talk w the cart & n64 & lcd screen. See. I was Given the Z64 from a Site who use to sell them, and had a N64 Laying around From one of those Blockbuster Pokemon Snap Stations.. (by the way, it was just a Normal Pokeman Snap Game off the shelf)
Sarah
Ummm, the z64 uses a very specific voltage ram. You can't drop just any voltage ram in it.
_kid
The processor supports 2G of address space. The builtin sram controller is able to address, control and refresh up to 16 megabytes.
If you want to add more, you need an external memory controller.
You just need to write an email to Acer Labs, Inc, asking for the datasheet of the part. Note: the V3.x hardware has a custom version of the chip, which includes extra logic inside the die, for that one you CAN'T get the pinout AT ALL. most of the pins are in common with the pc-on-a-chip part found in V1.x and V2.x hardware.
Yes, only the interrupt and dma control lines are not connected. Assuming you want to use it for a ne2000-like network card, you could route pin 149 of the CPU to pin 45 of the pc104 connector to enable the IRQ5 line.
The Z64 has a 8255 mapped to ports 0x0168-0x016b, port A points to LCD D0-D7, port B bit0: pin E, bit1 pin R/W, bit2 pin RS. The LCD has the standard Hitachi interface. The 3 buttons are accessed via port C, bit0 = large button, bit1 = down, bit2 = up.
The cart emulator DRAM and the physical cart port are accessed via I/O ports 0x0160-0x0167.
You can put a PC104 vga on the expansion slot. The z64 bios (the PC bios) will configure and use it. There's even a point on the motherboard where you can attach a PS/2 keyboard...
CoYoTe99
_kid..
You the Man!
With those Port Assignments, It looks that it was Dev'd On a Normal PC first....hmm..very interesting..
on another note.. Have you tried to Build an External Memory Controller?
thanks.
_kid
The Z64 is in fact a complete PC by itself (it runs an MSDOS clone too), and it would be technically relatively easy to build a Z64-on-isa card to attach to a normal pc.
Building an external memory controller would be more or less pointless, the Z64 has more than enough memory as it is -- you can even expand the internal ram to 1 megabytes (from its original 512k) by simply soldering in a chip; this is useful, if you plan to add a network interface to the Z64.
just64bits
if 512mbits games had come out earlier (like 2 years ago) then there is a chance that this support would get done by Z64 folks because it is definitely, technically possible from hardware but now it's really history.... history ...
_kid
There are a lot of reasons it would have been even harder: the upgrade from 128MBits to 256Mbits required a complete motherboard replacement (because the pld that did the cart emulation was soldered instead of socketed), the same lack of flexibility was carried even further: the new versions of the Z64 do have the cart emulation circuitry incorporated in the CPU: this required a relatively big production run (and was, most likely, done to allow a reasonably priced upgrade path), at that point running a new serie of cpus with the upgraded cart emulation hardware is completely out of question.
The thing that makes me wonder is *WHY* they didn't support, say, 4 or even 8 banks simms from start, as it would have taken just half a pagefull of code in the pld definition, given they'd commited the desing to be the "last ever".
CoYoTe99
Hey thanks for the posts man.. You def. know the H/W .. I didn't know there was actual Emulation Hardware Designed into the Cpu..
How hard would it be to constuct a ISA or PCI Emulation Hardware? Isn't The Z pretty much just feeding the Data the N requests to it?.. However the only part that would need to be constructed was a Pass though for the CIC chips.. But this could be simple acomplished by Sticking the on the Board and Adding some Software Controled 4053 or Other sim logic device to Switch between the Correct chips?
There isn't any schematics layin around that references the Address & Data Lines & Access SPeeds on the Carts Or a PC LPT Port <-> Cart Adapter Schematics Anywhere is there?
I understand the N is pretty much dead now.. I be very late in the game. But would be fun to attempt to play around with the concept since I have the interface board the Pokeman Snap Stations Used to Switch between carts to play with (has a nice 50 Scsi Header on it)....
_kid
The hardware in itself is quite simple, unless you plan to do fancy thing like transparent access to the memory by the N64 and the host system at the same time. There's even a site where you can find the complete schematic and pld code for a V64jr clone (www.pro.com.ru)
Not exactly. The cart emulation circuit does that. The Z64 cpu is more or less idle when the game is running.
The CIC chips can be simply switched by means of a ttl signal: all you have to do is to OR every clock line of each CIC with an active low chip select. This is probably the simpler part. The DRAM Bank controller and the refresh logic are the most complex component.
The site i mentioned contains enough to build your own V64jr, or even a simpler, flash based device.
Hardware hacking is fun even after years.
CoYoTe99
Thanks..
CoYoTe99
Does anybody have the content from www.pro.com.ru I now own a logic analyzer and want to play around.. cause i am bored -)
..never mind i found it.. derr ;o)
tcdev
Apart from the extra row/column/bank to which someone in this thread has already alluded, differing sized memory modules have differing geometries - you can even get the same size module in different geometries (ie.row/col/bank).
It's not trivial to produce a linear memory map from a mixture of geometries. The ASIC is hard-wired to expect a certain geometry, and anything that doesn't match simply won't work. The BOIS has *nothing* to do with it (as someone pointed out). And may be the reason why not *all* 32MB SIMMS don't work (rather than the questionable "special voltage" claim that someone made).
That aside, ppl have been musing over the possibility of designing some h/w of their own, much like PVbackup. And it certainly isn't that difficult.
The N64 doesn't execute of out cart ROM - it DMA's blocks into RAM in the N64 and then executes from there. This is why N64 'backup' units aren't simply EEPROMS - they need to be DMA targets. Of course, you need the CIC support as well.
I'm currently working on a board that plugs into NES, SNES & N64. Rather than RAM-based, it's flash-based, which means it doesn't need to be connected to a PC in order to play games. And it's portable without requiring re-programming! On the down-side, it's also more expensive. But, it's primarily for development/hacking work rather than ROM pirates!!!
I only got into the N64 scene very recently (as with NES, SNES) but I'd have to agree - hacking is fun, even if it is late!!!
Regards,
