new 8MB XMM expansion board
AntoineDoinel
Posts: 312
http://www.rlx.sk/sk/storage-boards-memorystorage-boards-memory/2559-ramdisk-8mb-8mx8-8mbytes-with-8bit-parallel-access.html
I've acquired some of those 8MB memory modules to use as swap/ramdisk with RetroBSD running on PIC32.
Unfortunately it was not an easy fit for my platform (DuinoMite) without hacking some extra wires to the CPU board.
So I tried to have it working as external memory for Propeller instead: seems to work nicely, and it's quite roomy for that price!
If anybody is interested, I have xmem driver for gcc done.
I've acquired some of those 8MB memory modules to use as swap/ramdisk with RetroBSD running on PIC32.
Unfortunately it was not an easy fit for my platform (DuinoMite) without hacking some extra wires to the CPU board.
So I tried to have it working as external memory for Propeller instead: seems to work nicely, and it's quite roomy for that price!
If anybody is interested, I have xmem driver for gcc done.
Comments
Paypal?
No @%*$#! :frown:
I tried asking them, but no way... I had to take half day off work to do a wire tranfer.
But other than that, I have to say that it's very nice: it takes only 12 pins (or even 11 if you keep it always enabled).
Although it's not a speed monster (it uses 70ns PSRAM), the read/write loop still does one byte in 32 clocks, wich is not bad at all. I tested it on 100MHz clock protoboard, so it should be stable, expecially at 80MHz.
I would love to buy one, but hate to pay multiples of the price for banking and shipping.
But I still can't add the item to my Shopping Cart to see where that leads as far as shipping and payment. The icon "ADD TO CART" is missing for this particular item. I had figured that I might be able to order two or more and spread the shipping and other costs.
But it seems to not currently be on sale. It doesn't really matter as I did select a Propeller ASC+ and they don't ship to Taiwan. Never got as far as trying my credit card.
I ordered three memory modules and some other bits, so shipping fees were not a problem.
A lady named Lucia contacted me and asked if I was ok to wait for something in backorder.
They were somewhat secretive, and only revealed the info necessary for wire transfer when everything was ready for shipping. But apart from minor communication issues, everything went smoothly.
I suppose they're out of stock now.
As I understand it, the module was developed by two guys: "Jaromir" for the hardware and CPLD code, and "Pito" for the BSD driver. Expecially Pito seems active on RetroBSD forums.
I tried asking a question there, but that forum will not begin to work until your first post is approved by mods.
Maybe my post slipped under their radar, because it was not published.
Maybe we could ask on that forum if they plan another production run?
I have to say that I'm having a blast with this thing!
I know many here will raise an eyebrow and say the usual "you're treating a microcontroller like a microprocessor!"... but having a huge memory it's just too fun, including the limited speed!
Experiments include quick adaption of: MMBasic (DOS version), a CPM-68K emulator (based on Musashi), 8086tiny simulator and more! (not that they're actually "ported" or "working", but merely hacked "until first signs of life").
Plan A: I'll try again to get in contact and ask.
Plan B: you could make some more of your 32MB SDRAM expansion boards?
Maybe with a second latch to reduce pins?
Note they're using a tiny 32 macrocell CPLD, just enough for auto increment counters.
SDRAM might be harder to get timing right, but there is the advantage of embedded streaming and faster speed.
I guess it's possible to use propeller counters in gcc memory drivers, to make burst loop 16 clocks, but nobody tried yet... is this correct??
Plan C: XMOS seems to offer a plugin module with just the SDRAM chip on it. So I guess sharing address and data it's definitely possible, provided the /OE line is available. At that point it makes sense to "burn" some total 20+ pins but going to a 16bit bus. What do you think?
Attached the driver source to the first post.
I'm not including the .dat blob because I'm compiling it on linux, and while everything works there, the .dat file doesn't work when dropped in propeller-load dir on Windows.
It's way too small wrt the other drivers, there is something that I'm missing?
Taiwan may never be possible. My US credit card doesn't have any problems with purchases all over the world. On the other hand, PayPal on a US account seemed to be unwilling to ship outside the USA.
I suspect the vendor is a bit wary of wire transfers as you have to request some banking identity data, a SWIFT account and particulars about your personal account identity that might or might not be wise to hand out to just anybody. I use the wire transfer to move cash to Taiwan for living expenses about once a year, but that is all I use it for. It is not really intended for small transactions.
Parallax is selling the Propeller Memory Card.. easier to order.
http://www.parallax.com/product/40004
Like this?
Yes, I have two of Rayman's RamPage (v1) modules, which can be considered somewhat equivalent to Propeller Memory Card when paired with an SD card (except you have to juggle command bits around before sending to SRAMs).
Anyway we had medium sized XMM for ages now, but the only large solution was Jazzed's SDRAM card which I missed when it was on sale: I'm talking about ~1300KB code (hopefully choosen among many from SD card in the future, not only AUTORUN.PEX), plus some 4MB malloc'd from heap! :cool:
Yes this one! Did you get any of this 14pin version boards produced back then?
No, I didn't.
If there is sufficient demand, I could do a custom footprint. I'm a bit reluctant though.
A SIP Single Inline Pack 14 pins+VDD+VSS version could be usable on the Activity Board (or other boards).
A P2 design could use this too, but I think the number of pins available with that might make a non-latched version more attractive.