NeXT DSP Memory Expansion Module

[NeXTnewbe]

I would like to get one of this boards, if you guys are going to replicate them

let me know

Thnks

[Nitro]

I would like to get one of this boards, if you guys are going to replicate them

let me know

Thnks

I exchanged e-mails with Tom Holton of SFSU a long time ago and he said that he would look to see if he still had any of the original documentation for the memory module that they produced, but he didn't sound optimistic that he still had the information.  He did say that he still had his Slab though.   I sent him a follow up e-mail a few months later but didn't receive a response.  So the project is stalled at this point.  If anyone has the expertise to help with this project feel free to send me a PM or e-mail to admin at nextcomputers <dot> org.

Thanks,

[NeXTnewbe]

I think that we need to do a list of the tasks and research required, and then we can choose accordingly our skills

my electronics are a bit rusted , as I have a degree in Computer science, but haven't applied eceltronics in a very long time (as I work in Telecommunications and Network Security)

please let me know what you think?

[NeXTnewbe]

a crazy idea why not take an X ray on one of the DSP expansions to see the middle layers?


:oops:  :oops:  :oops:

[NeXTnewbe]

Hi everyone

I got a really fantastic news! I had contact Tim Holton the original designer of the NeXT DSP module few weeks ago, and today he has send me the diagrams a some other information to recreate the module

the only requirement is to keep his intellectual copyright of this work, he also told me that hi has send a copy of thesam information to other memeber of the forum

how can I upload the information

and who is interested in help me and recreate the module, lest organize a team, who's with me?


Yupieeeee

[pentium]

Wait, so you might have complete schematics?
Fantastic!

I'm totally in. I know people here who would gladly love a DSP module in their slab or cube.

[NeXTnewbe]

Wait, so you might have complete schematics?
Fantastic!

I'm totally in. I know people here who would gladly love a DSP module in their slab or cube.

here is a part of his email t

"Here is a pdf file of some of the info for the 576KB DSP memory module my student Joel Miller and I made for the NeXT computer many years ago. I have a very thick file on this, from which I'm sending you what I feel are the really relevant pieces: the schematic, which gives the pin-outs, and the mechanical fab drawing that gives the dimensions of the board. With this information plus a data sheet for the memory, a competent designer should be able to redesign the part with modern components. A redesign will be necessary because the particular Micron memory SRAM part we used is long gone. Although you might be able to find some of these parts on the used market, I would strongly advise against it based on my negative experiences with them. Most of these parts don't work. You're better off redesigning the module using more modern memory chips. I've enclosed copies of the foils of the layers just for your amusement.

   You are welcome to share this as you see fit, though from a purely legal standpoint we do retain the copyright on this work."

so how can we modify this, and all we need to do is keek him informed and make sure he and Joel are mentioned always as the original designers of the DSP

so how can we organised this?

[Nitro]

I e-mailed Tom about this project on January 29th, 2008 .  He sent me a belated response on September 14, 2009 with a promise to scan and send documents relevant to the NeXT DSP memory module.  I received a PDF document yesterday with most of those details.  Tom Holton and his student Joel Miller rightfully retain the copyright to all documents related to the original design.  The PDF file he sent has some nostalgic info and contains recommended reading:

http://www.nextcomputers.org/NeXTfiles/Projects/DSP_Expansion_Ram/SFSU_NeXT_DSP_Expansion_Memory.pdf

We thank Tom so much for taking the time to record this for the NeXT community!  

NeXTnewbe, would you like to lead this project?  Please, please, please!    The documents we have so far are located here:


http://www.nextcomputers.org/NeXTfiles/Projects/DSP_Expansion_Ram/

[NeXTnewbe]

I was the guy who made him remember your email Nitro, he mention that you have contacted him few years ago, but he was so busy that he totally forgot it.

I got some other technical documents with the old Micron memory and the hex inverter specification for the original Tim's module, and in fact this DSP expansion module is totally different, to the one we all know (at least in pictures).

Nitro, please we need to add a disclaimer, and giving all credit to the original module to Tim and Joel for the module, this should be a "Must", to make sure we are on le legal side all the time.

I will like to help with the project, but I need to know who is willing to help, and understand our skills.

I don't have too much time to spend on this, but definitively I want this module in my cube.

The original Tim's DSP memory uses the following modules

6x Micron MT5C1008 at 35 ns
1 x 74ALS04B Hex inverter
and some ceramic capacitors


so we need someone to help us to find the most modern memory modules compatible with the original modules. then the question to the forum member is who among us have the skills/experience to help us.

this is the first and most hard part, once we have the design we wee to produce a part to test and the cost is something we will need to agree how to split the cost for the fist module and the subsequent modules

Nitro, how can I upload information to the Filearchive? I will put more bits that I got regarding the module

Thanks

[cuby]

I got some other technical documents with the old Micron memory and the hex inverter specification for the original Tim's module, and in fact this DSP expansion module is totally different, to the one we all know (at least in pictures).

Electrically, they seem quite similar - U7 is a hex inverter, the RAMs used are identical. I'll have to check which module actually is used in my Dimension Cube.

so we need someone to help us to find the most modern memory modules compatible with the original modules. then the question to the forum member is who among us have the skills/experience to help us.

The Micron part is a pretty standard asynchronous 128kx8 SRAM with 35ns access time. I'm not sure if the DSP really requires 35ns parts, but nowadays, async SRAMs with 10ns are available, so speed is not a problem. Using SMD parts, a e board might even be a bit smaller.

Farnell has the following IC's:

CYPRESS SEMICONDUCTOR CY7C109D-10VXI (128kx8, 10ns)
INTEGRATED SILICON SOLUTION (ISSI) IS61C1024AL-12JLI (128kx8, 10ns)

There are larger memory capacities available, but I'm not sure how much external RAM can be attached to the DSP56001.

this is the first and most hard part, once we have the design we wee to produce a part to test and the cost is something we will need to agree how to split the cost for the fist module and the subsequent modules

The layout is rather simple - the original design uses a 4-layer-board, which would have to be manufactured (i.e., I can't do a prototype in-house here). Not sure about the current prices for 4-layer PCB manufacturing, 2-layer boards were about 50 Eur/board (160x100 mm^2).

-- Michael

[cuby]

Hm, according to the DSP56001 data sheet, only 16 address lines are available. So, only half of each 128kx8 chip is used (the A16 line is tied to GND in the schematic). What a waste of resources!  

EDIT: actually, three of the 128kx8 RAMs (data RAM) are used to 100%, A16 selects between X and Y memory accesses. Only the program RAM is 50% unused.

However, the following question is still valid :-):

Did anyone consider building some kind of bank-switching logic for the DSP?
I'll dig a bit deeper into the data sheets, last time I worked with the 56001 is nearly 20 years ago...

-- Michael

[NeXTnewbe]

I actually got some plans to use the DSP on my cube, and the DSP memory seems perfect fit,


I know, I know I can do much with modern HW but the fact to see my beloved cube doing something else is just exciting

[pentium]

I'm still willing to to do the testing and I can go as far as assembly and design of the new SIMM however I have no means to produce the PCBs.
two of the designs for the new SIMM that I thought up were piggy backing two PCBs (similar to what SGI Origin 2000 ram looks like) and the other was making the board in a weird L-shape.

[NeXTnewbe]

I was checking some static RAM the CYC109BN,  CYC1009BN and the IS62WV1288DALL/DBLL and the IS65WV1288DALL/DBLL are the exact type of memory as modemr component, the diference is the speed.

but for the IS6xWV1288DALL available speeds in 35ns too

for the Hex inverter as simple and still in the market, my thoughts on this two chips, that can be use to replicate the same original design without any change

can anyone confirm this, please?, if so, it would far easy

so far I recreating the schematic in cad, but I don't have the skills to do the PBC circuit diagram at scale (who can help ?)

[cuby]

I was checking some static RAM the CYC109BN,  CYC1009BN and the IS62WV1288DALL/DBLL and the IS65WV1288DALL/DBLL are the exact type of memory as modemr component, the diference is the speed.

but for the IS6xWV1288DALL available speeds in 35ns too

for the Hex inverter as simple and still in the market, my thoughts on this two chips, that can be use to replicate the same original design without any change

can anyone confirm this, please?, if so, it would far easy

This should work, just make sure the parts you use are 5V-compliant (modern parts often run on 3.3V signal levels).

so far I recreating the schematic in cad, but I don't have the skills to do the PBC circuit diagram at scale (who can help ?)

Which CAD system are you using? Eagle offers a limited free version (up to 100x80 mm^2 PCB area, 2 layers) of their PCB CAD system for Linux, Windows and OS X. While the original design uses four layers, a first prototype on two layers might be possible.