The Crumar GDS Restoration Blog...

[HideawayStudio]

I am currently in total bewilderment of the incredible hulk of 35 year old digital uber unobtainium that I'm staring at having just booted in my workshop after 20 intense hours straight

The jaw has hit the floor!!!



Following the popularity Novachord 346# restoration blog I've been very tempted to do the same with the GDS...

[Zamise]

An operating system that runs under 64k off a floppy in 1980? Looks DOS based? >LOAD STARWAR!

[silikon]

That kiddies, is the Crumar GDS. Unobtanium indeed. Runs on DOS' predecessor, CP/M; not unlike the Synergy (which is a direct descendent of this machine).

..I can't recall if the GDS uses 8" floppy disks or 5.25", but somehow I believe it was the larger of the two.

Outstanding, this.

Dan, what did you end up having to do to get that beast running?

[HideawayStudio]

That kiddies, is the Crumar GDS. Unobtanium indeed. Runs on DOS' predecessor, CP/M; not unlike the Synergy (which is a direct descendent of this machine).

..I can't recall if the GDS uses 8" floppy disks or 5.25", but somehow I believe it was the larger of the two.

Outstanding, this.

Dan, what did you end up having to do to get that beast running?

Just a single 8" floppy disk drive mechanism from the GDS is as big as a three modern laptops on top of one another and the spindle motors run on 220 volts AC!

This is just the start of a major restoration exercise as part of a feasibility study so naturally managing to make the host computer boot up at this stage is very exciting.

There is a heck of a lot to do and I am tempted to blog it as I did with my Novachord on VSE.

The GDS is extremely rare - only 10 were ever built at $30,000 each in 1979. I have managed to make contact with almost the entire surviving development team who have been extremely helpful and have found a small mountain of documentation, drawings and even digitally archived data for me.

...but it it's even more special than that...

In the paperwork that came with the instrument are letters from the dev team to Klaus Schulze which completely line up with past events described on both the US and German sides!!

[Bitexion]

What the h**l is it? Some kind of ancient sampler with software like the Fairlight CMI?

[silikon]

[desmond]

What the h**l is it? Some kind of ancient sampler with software like the Fairlight CMI?

There's this cool thing called Google which lets you find out stuff. For example, it gave me these:-

http://en.wikipedia.org/wiki/Crumar
http://www.analogindustries.com/b42/
http://synthmuseum.com/synergy/index.html
http://www.synthony.com/vintage/dkigds.html
http://www.muffwiggler.com/forum/viewto ... d2bdf23435

They are quite interesting.

[HideawayStudio]

What the h**l is it? Some kind of ancient sampler with software like the Fairlight CMI?

The GDS was decades ahead of it's time - its a 100% 16-bit digital synthesizer with 32 oscillators offering a mix of both additive and FM/Phase Distortion synthesis based on the Bell Labs Synth by Hal Alles from even earlier and who helped directly to commercialize the concept as the GDS and then the Synergy....

It was used by both Wendy Carlos (still with Wendy) and Klaus Schulze (this one).

Hear my demos of the Synergy - it is the exact same synth engine:

[madtheory]

!!!When did you get Klaus Schulze's GDS?!?!?! Please blog about it The Novachord blog was great. This GDS could not be in better hands.

[HideawayStudio]

!!!When did you get Klaus Schulze's GDS?!?!?! Please blog about it The Novachord blog was great. This GDS could not be in better hands.

Its been on the cards for several months now but it wasn't something that could be made known at the time.

I am deeply indebted to surviving members of the original GDS design team in the US including Hal Alles and Stoney Stockwell for helping me with this project. I am now in an unusually strong position to tackle the restoration of such a rare instrument.

What they are telling me is that only around 10 were ever built but maybe as little as 2 to 4 were ever sold to customers as outright sales.

Needless to say that I have to handle some aspects of this instrument with extreme kid gloves until backups have been made - eg. the contents of the IPL boot code PROM in the host computer.

I will blog progress for sure.

[desmond]

Looks a really interesting project - will follow along for sure if you blog it - and the Internets will owe you for it!

[HideawayStudio]

The mighty GDS Keyboard console with its plethora of control sliders:


The rear of the IMS8000 host computer with the custom synth boards currently removed:

[HideawayStudio]

I really like these stories behind the development of interesting gear, particularly the human stories, and the challenges of making something great with very primitive (by today's standard) tech...

Well the first tidbit is that this is the very example that was used to make the album Dig It.

http://www.discogs.com/Klaus-Schulze-Di ... ster/29542

[silikon]

I really like these stories behind the development of interesting gear, particularly the human stories, and the challenges of making something great with very primitive (by today's standard) tech...

Well the first tidbit is that this is the very example that was used to make the album Dig It.

http://www.discogs.com/Klaus-Schulze-Di ... ster/29542

Question: beyond the fact that it boots from an 8" floppy, how similar are the innards of the actual host cabinet to your typical S-100 bus system?

[HideawayStudio]

I really like these stories behind the development of interesting gear, particularly the human stories, and the challenges of making something great with very primitive (by today's standard) tech...

Well the first tidbit is that this is the very example that was used to make the album Dig It.

http://www.discogs.com/Klaus-Schulze-Di ... ster/29542

Question: beyond the fact that it boots from an 8" floppy, how similar are the innards of the actual host cabinet to your typical S-100 bus system?

Actually although the computer technology is indeed primitive by today's standards, the unique method of implementing highly accurate phase controlled digital oscillators is remarkable and quite tricky to implement even in today's technology as the latency figures are tight so you can't simply throw CPU power at the problem and expect it to work properly. It's really a task for a carefully coded DSP.

There simply wasn't enough processing power available in those days to do it the belt and braces way in 100% software so basically the whole oscillator board is implemented in logic as a custom discrete ALU performing all of the maths to calculate, interpolate, manipulate and sum/multiply 32 oscillators on the fly in real time.

The host computer itself is a stock IMS8000 CP/M machine with S100 cards for Z80 CPU, I/O, 64K DRAM and Floppy Controller. There are then additional custom cards sitting on the S100 bus designed by Crumar/MTI handling the keyboard, keyboard control circuits and the interface to the high speed oscillator board which is very large and mounted directly under the top lid in the computer chassis. The the development of this subsystem is truly remarkable - it is basically the result of costing down some 1200 circuits of the equivalent oscillator bank in the $100,000 300 pound Bell Labs Synthesizer with some great minds applying a great deal of ingenuity, clever use of programmable logic and sheer determination. This pcb is the very same oscillator card that was eventually mounted under the keybed in the Synergy.

To be honest this is about as nerdy as synth design ever gets - it was truly groundbreaking stuff.