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NeXT DSP Memory Expansion Module
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barcher174



Joined: 07 Dec 2012
Posts: 556

PostPosted: Sat Jul 15, 2017 12:52 am    Post subject: Reply with quote

Hi Rob, did they give you a cost estimate?
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bobo68



Joined: 03 Jun 2015
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PostPosted: Sat Jul 15, 2017 5:48 am    Post subject: Reply with quote

Rob Blessin Black Hole wrote:
So I no have the NeXT DSP memory expansion module and would like to proceed with using it to make modern clones of the chip. Any thoughts?


Very cool, Rob. Is it a NeXT 96K module or something else (like the one from the SF State Uni)?
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Rob Blessin Black Hole
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Joined: 05 Sep 2006
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PostPosted: Wed Oct 04, 2017 3:02 pm    Post subject: Reply with quote

Hello NeXT Community: Apologies for not posting , my dad's is been in the ICU for 3 weeks , today he has finally moved to a regular bed long story.
I thought you all may have an opinion on what I have stumbled upon. I found I had some old Apple 512K 64 pin rom's from 1988, thought huh , NeXT DSP is 64 pin , the idea of the Apple was to address 32 bit upgrade from earlier 24 . I said what is the worst that can happen lol , well no fireworks check out video she boots. Now I'm trying figure out if it is actually doing something https://youtu.be/rgmYGCdPCO4 , so now to look for bench marks or something , any help appreciated ,
I bought 2 more from eBay ,they are from 89 , may be I'm onto something as I seem recall wayback hearing about this I swear stuff warps in here all the time .
Now I am in a unique position to test it with my original NeXT dsp expansion chip as well and with no chip in the expansion slot .

May be our answer was hiding in plain site this whole time .
If they are dormant and in place can they simply be reprogrammed?

Brian, helped me out on this one as apparently it is the same packaging but electrically not compatible with NeXT . SO a NO GO?

I thought may be because of the time 1988 and many Apple engineers working at NeXT were from Apple , may be they had a plan to do this , It was interesting how closely everything NeXT paralleled Apple in terms of specs , the main difference being DSP and yet NeXT used a DSP expansion port that was 64 pin which matches the Apple 512K Rom. The Apple Rom has VLSI Chips on it which in turn can be used for DSP ? Here?
http://read.pudn.com/downloads138/ebook/594519/biomedical%20digital%20signal%20processing/chapter14.pdf Best Regards Rob Blessin
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Rob Blessin President computerpowwow ebay sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93
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cuby



Joined: 12 Jan 2006
Posts: 164
Location: Coburg, Germany

PostPosted: Thu Oct 05, 2017 3:43 am    Post subject: Reply with quote

Rob Blessin Black Hole wrote:
Hello NeXT Community: Apologies for not posting , my dad's is been in the ICU for 3 weeks , today he has finally moved to a regular bed long story.


Ouch. All the best...

Quote:
I thought you all may have an opinion on what I have stumbled upon. I found I had some old Apple 512K 64 pin rom's from 1988, thought huh , NeXT DSP is 64 pin , the idea of the Apple was to address 32 bit upgrade from earlier 24. I said what is the worst that can happen lol , well no fireworks check out video she boots.


The ROM SIMM itself won't work for the simple reason it's a ROM, not a RAM. Another difference is the bus width, the 68k needs 32 bit, the DSP56k has a 24 bit address bus.

However, the situation is worse and you probably got lucky that the "magic smoke" didn't leak out, since the pinouts of the modules are different The JEDEC pinout for ROMs and RAMs is very similar (see
The Mac ROM SIMM pinout can be found here: https://wiki.68kmla.org/ROM_SIMM_Pinout. Steve Chamberlin has created a reprogrammable Flash ROM version https://www.bigmessowires.com/mac-rom-inator-ii/.

The NeXT DSP RAM extension connector is detailed here http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Schematics/Turbo_cube/Cube33-09.pdf.

As you can see, the pinouts have almost nothing in common, so you probably got quite lucky that everything survived...

Best,
Michael
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Rob Blessin Black Hole
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Joined: 05 Sep 2006
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PostPosted: Thu Oct 05, 2017 6:29 am    Post subject: Reply with quote

Best,
Michael[/quote] Thanks I removed it from the NeXT DSP slot . Best Regards Rob Blessin
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Last edited by Rob Blessin Black Hole on Mon Oct 16, 2017 10:31 am; edited 1 time in total
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SlateBlue



Joined: 23 Aug 2015
Posts: 75

PostPosted: Sat Oct 14, 2017 11:44 am    Post subject: Reply with quote

bobo68 wrote:
Rob Blessin Black Hole wrote:
So I no have the NeXT DSP memory expansion module and would like to proceed with using it to make modern clones of the chip. Any thoughts?


Very cool, Rob. Is it a NeXT 96K module or something else (like the one from the SF State Uni)?


It's the same 96k module you and I were working with. I had to part with my NeXT collection for a few reasons... Sad
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bobo68



Joined: 03 Jun 2015
Posts: 194
Location: Germany

PostPosted: Sat Oct 14, 2017 2:00 pm    Post subject: Reply with quote

SlateBlue wrote:
bobo68 wrote:
Rob Blessin Black Hole wrote:
So I no have the NeXT DSP memory expansion module and would like to proceed with using it to make modern clones of the chip. Any thoughts?


Very cool, Rob. Is it a NeXT 96K module or something else (like the one from the SF State Uni)?


It's the same 96k module you and I were working with. I had to part with my NeXT collection for a few reasons... Sad


What a pity. I hope things are changing for the better for you.
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Rob Blessin Black Hole
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Joined: 05 Sep 2006
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PostPosted: Mon Oct 16, 2017 10:40 am    Post subject: Reply with quote

The ROM SIMM itself won't work for the simple reason it's a ROM, not a RAM. Another difference is the bus width, the 68k needs 32 bit, the DSP56k has a 24 bit address bus.
https://wiki.68kmla.org/ROM_SIMM_Pinout. Steve Chamberlin has created a reprogrammable Flash ROM version https://www.bigmessowires.com/mac-rom-inator-ii/.

The NeXT DSP RAM extension connector is detailed here http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Schematics/Turbo_cube/Cube33-09.pdf.

Light bulb?

Now call me crazy but how programmable is the "rominator" so obviously we need 24 bit addressing not 32 what I'm getting at is it has a flash program would it be as simple as flashing
or rom burning it with the right code.
I've asked Steve:
If we can make modifications easily as it looks like he has a programmable chip solution and if rom to ram is emulation possible.
Steve has the 64Pin PCB template and a manufacturer in place to make 64 pin simms hopefully,

My thought all we need is to matchSteve's 64 pin PCB board by mounting compatible programmable DSP chips

and then program them with DSP ram burner code may be it is built in to NeXTSTEP? ,

his rominator has a lightening connection so in theory we can burn the dsp code needed for NeXTSTEP to handshake with our modules to the compatible DSP chips and

So we draw up the routing on the 64 pin PCB to address 24 not 32 bit addressing using the schematics from NeXT and give this to the manufacturer and

We just use the specs from the SFSU 512K expansion module as it is done already ? Best Regards Rob Blessin http://www.nextcomputers.org/NeXTfiles/Projects/DSP_Expansion_Ram/SFSU_NeXT_DSP_Expansion_Memory.pdf What happens if we use this to read a DSP CHIP? https://www.bigmessowires.com/shop/product/rom-simm-programmer/
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303-741-9998 Serving the NeXT Community since 2/9/93
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Rob Blessin Black Hole
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Joined: 05 Sep 2006
Posts: 591
Location: Ft. Collins, Colorado

PostPosted: Sat Oct 21, 2017 1:40 am    Post subject: Reply with quote

Hello NeXT Community:
I found this Kingston 64 pin ram stick , it is unusual as not a lot of 64 pin stuff apparently some 1989 Macs maybe used 64 pin ? My guess is this simm is Ram not ROM and probably cost $500 .
Question it was in with a bunch of NeXT stuff and
I pictured it NeXT to a NeXT DSP Chip obviously I don't want to smoke a board or the chip or both but would this possibly be compatible with the NeXT DSP expansion slot . I'm not trying to be stupid here but curious .
and

Steve Chamberlain and BMOW pointed me to a company that potantially will produce 64 pin simms , in small quantities, source the components and laser etch the custom pcb boards but the catch is I need a nice schematic for the DSP . Would anyone be able to clean up the DSP schematic in the archive or draw up what we need to make chip. I think now the technology has caught up to where we have a chance to make these for a reasonable price https://www.elecrow.com/pcb-assembly.html Any thoughts? Best Regards Rob
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cuby



Joined: 12 Jan 2006
Posts: 164
Location: Coburg, Germany

PostPosted: Sat Oct 21, 2017 5:03 am    Post subject: Reply with quote

Rob Blessin Black Hole wrote:
Hello NeXT Community:
I found this Kingston 64 pin ram stick , it is unusual as not a lot of 64 pin stuff apparently some 1989 Macs maybe used 64 pin ? My guess is this simm is Ram not ROM and probably cost $500


That's a DRAM SIMM for a Mac IIfx - completely different, sorry...

Quote:
Steve Chamberlain and BMOW pointed me to a company that potantially will produce 64 pin simms , in small quantities, source the components and laser etch the custom pcb boards but the catch is I need a nice schematic for the DSP . Would anyone be able to clean up the DSP schematic in the archive or draw up what we need to make chip. I think now the technology has caught up to where we have a chance to make these for a reasonable price https://www.elecrow.com/pcb-assembly.html Any thoughts? Best Regards Rob


The DSP SIMM ist's complicated - I can try to convince one of my students to design one (would do it myself, but I don't have that much free time at the moment). The SFSU board uses a four-layer design, that will make the PCB a bit more expensive. Perhaps we can get a two-layer board to work.

The RAMs themselves are simply 32 k x 8 or 128 k x 8 SRAMs (giving 96 or 384 kB extra memory, since the 56k memory bus is 24 bits wide - or twice the amount if separate RAMs for program and data space are used, as in the SFSU board). The only additional part on the SFSU DSP memory expansion board is a simple inverter.

A quick check of the inventory at mouser shows suitable SRAM chips (IDT 71024S20YGI8 20ns) available for less than 3 in single quantities, the inverter (74ALS04) costs about 0.60.

-- Michael
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cuby



Joined: 12 Jan 2006
Posts: 164
Location: Coburg, Germany

PostPosted: Sat Oct 21, 2017 5:11 am    Post subject: Reply with quote

Here's a picture of a DSP56k memory expansion for some ancient Motorola eval board - I have a number of old DSP56k board in my lab here and even a 56k in-circuit emulator (which requires a PC with an ISA slot, however...).



-- Michael
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Rob Blessin Black Hole
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Joined: 05 Sep 2006
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PostPosted: Sun Nov 05, 2017 5:25 pm    Post subject: Reply with quote

Hello NeXT Community: http://www.nextcomputers.org/NeXTfiles/Audio/DSP/DSPbug/ would be very useful for designing the chip and looking at the current one Debug 56 app bundled under NeXTSTEP 2.1 , amazes me when I find cool old apps that have been there all along! Best regards Rob
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