DSP Cache memory upgrades?

Started by helf, April 05, 2007, 07:13:35 AM

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helf

Anyone ever seen any of the memory upgrades for the DSP on NeXT systems? They apparently were able to max it out at 576KiB of RAM...
After an apparent 15ish year hiatus... I'm baaaaack! :D (12/12/2023)

MacG4

Quote from: "helf"Anyone ever seen any of the memory upgrades for the DSP on NeXT systems? They apparently were able to max it out at 576KiB of RAM...
heard about em, but have never actaully seem them
"keeping the NeXT legacy alive one day at a time"
-NeXTStation Mono, NeXTStation Turbo Mono, NeXTStation Turbo Color-

Andreas

Quote from: "helf"Anyone ever seen any of the memory upgrades for the DSP on NeXT systems?

Yes i have seen one in original package on eBay. I have also bidden on that but with no chance, so i assume it was gone for a lot more than a few hundred dollars. (if i remember correctly i have bidden about $200)

da9000

WOW! That's a crazy amount!

What I'd be more interested is the programming manuals for the DSP subsystem. Are these available someplace?

tech_head

I did some DSP programming. For audio mostly.
I also designed a custome A/D and Digitial I/O board.

Quote from: "da9000"WOW! That's a crazy amount!

What I'd be more interested is the programming manuals for the DSP subsystem. Are these available someplace?

da9000

Quote from: "tech_head"I did some DSP programming. For audio mostly.
I also designed a custome A/D and Digitial I/O board.

Hey tech_head, that's pretty cool! Could you please give us some more info on the development tools and manuals for this? Also, is the DSP programmed via memory mapped I/O, can it do DMA to the main memory, etc ? Give us as many details you can/want for the stuff you did with on the NeXT/DSP.

Thanks in advance for the info!

Nitro

Quote from: "helf"Anyone ever seen any of the memory upgrades for the DSP on NeXT systems? They apparently were able to max it out at 576KiB of RAM...

Here's a picture of the original NeXT DSP memory expansion module.



Source: http://www.geocities.jp/next_freak/next-funto3.html

It's a standard JEDEC 64-pin SIMM footprint.  I tried a 1Mb 64-pin SIMM designed for an Apple Mac IIfx or LaserWriter, but my Turbo Color Slab would not boot with the SIMM installed.  So apparently it's a unique design.  At some point I'd like to start a project to clone both the original 96Kb NeXT part (N7013) and the 576Kb part made by San Francisco State University.  There was mention of such a project on comp.sys.next.hardware ~7 years ago, IIRC.
Nitro

korneluk

The DSP expansion memory has a special layout as described below:

"Off-chip DSP memory on the NeXT computer exists in two address ranges, each of which spans all of the 8K words of external memory. In the first address range (8K to 16K), x, y, and p memories are overlaid; that is, an external memory reference points to the same off-chip location regardless of the memory space specified. Note that in this address range, there is no l memory space support. (The high and low words are mapped to the same word.) In the second address range (40K to 48K), x and y are split into separate 4K partitions, and p overlays the entire 8K. This address region allows external l memory use, and supports algorithms (such as the Motorola benchmarks involving complex data) which expect x and y memories to be physically separate".

I found this info on an article by Julius O. Smith from Next and Stanford U.

idylukewild

Nitro-

Have you got the circuit design from the SFSU team? If they produced a finished, working, DSP expansion there may be someone willing to get the circuit diagram and art for the boards to you. That stuff tends to stay around forever now that it can be contained in digital form (unless everybody associated with the project has passed away and/or didn't care enough to back up their files). I can't see why anybody would hold back from freely giving you that information, especially if you make it clear that it is for historical purposes only and that nobody will profit from the information. Then you'd have to get the correct chips...

Luke

korneluk

I'll gladly layout the PCB if someone can provide the schematic.

-- josé k.

Nitro

I sent an e-mail to Tom Holton of SFSU this afternoon requesting information and/or schematics of the module they designed.  The e-mail didn't bounce, so I'll keep my fingers crossed that he's still there.  I also sent an e-mail to Julius O. Smith requesting information about the NeXT RAM module, so hopefully he still has information on the subject.
I've done quite a bit of investigation over the past few days into building a new module.  The pin layout of the DSP expansion socket is on page 9 of the Turbo Slab schematics.  

http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Schematics/Turbo_slab/CSlab33_Schematics.tar.gz

I also have the part numbers of the SRAM and multiplexer chip used on the original NeXT module, so it should be possible to build a new RAM module with currently available cross-referenced parts.  However, I'm not an Electrical Engineer, so I may or may not be able to figure out the board layout/wiring.  :)  I'll start a community project in the NeXT worklog section and maybe we can get a collective effort going to build a new module.  Thanks for the informative responses.
Nitro

korneluk

Well, I am an engineer - or at least "I play one during the day".

Good idea with the community project. It would also be extremely cool if we could find more info on the Ariel Quint DSP / QuintProcessor.

http://www.nextcomputers.org/forums/viewtopic.php?t=871

-- josé k.

blackcube

I have one of the DSP SIMMs in my Dimension Cube.   I'm pull it as I  start to unpack stuff.
www.blackcube.org - The Texas State Home for Orphaned and Wayward Computers

korneluk

Could you loan me the SIM for one week so I can trace the circuit and get the part numbers off of it? I'll pay for postage both ways.

Thanks,

-- josé k.

idylukewild

I sent the following to [email protected] on Feb. 16, 2006:

"Mr. Holton-

Is your DSP memory expansion module for
a NeXTstation still available? I realize it has
been over ten years since the documents that
point to you have been written, but thought it
might be worth a try.

Luke"

The email address came from the NeXTFAQ bit
on the DSP expansion card. The mail did not
bounce back and I never got a reply. I did notice
there is a different email address for him on the
SFSU website:

Discipline: Digital
Office: SCI 170
Phone: (415) 338-2741
Fax: (415) 338-0525
Email: [email protected]