in the dive computer stone age ...

• a long time ago, i.e.: shortly after the disappearance of the saurians, there have been dive-"computers" as well ...
• N.B.: i didn't dive with these things and they are as well not in my museum
• but also I wanted to share with the diving community ...
• I recieved this information from my friends Karl E. Huggins, Catalina Hyperbaric Research;
• and from Ron Nishi, then DCIEM and, as well
• directly from the U.S.N. NEDU reports, the reports of United States Navy Experimental Diving Unit
• sources: pls. cf. below
  
• this animal is the "Decomputer Mark I"
• a pneumatic thing with 2 compartiments (t_1/2: 40 and 75 Min.) made by FOXBORO
• the allowed super-saturation ratio for both compartments was 1.75 : 1
• it has been developped in 1955 and then given to the NEDU in order to test
• it didn't became widely used because the stop times diverted by much from the USN table

• this is probably worldwide the first electronic dive computer
• it is from 1963 and has been developped by TRACOR, a subsidiary of the Union Carbide Corp.,
• in conjunction with the NEDU
• the display shows the safe ascend depth in feet
• it utilizes a 10-fold RC mesh for the simulation of a simple diffusion equation
• due to the strong temperature dependancy it never left the test bed at NEDU
  

  

  

• this thing is a desktop computer, developped by the DCIEM and CTF, Inc.
• it's the: XDC-1 from 1970
• it worked in conjunction with a "pneumo hose" (an air hose open on one end)
• this pneumofathometer was attached to a diver
• so the depths could be monitored on-line
• there was a Kidd-Stubbs Model inside, and with the dive time
• it gave the decompression times for this serial 4 compartment model

• the next one features a follow-up to the XDC-1, it is the:
• XDC-2, this one is still in use (2012) in the Hyperbaric Chamber of the Sacre Coeur Hospital in Montreal!
  

  

• I recieved these pictures from:
• Marc Essertaize, Chief Operator
• you see the front with the displays
• and the back with the connections to various power sources
• and the pneumo hose (Pressure Input, 0 - 150 PSIA) which is good up to 10.3 Bar

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• this thing i found in my favourite deco-book [102] Decompression Sickness from Hills, B.A. on p. 133:
• you could use up to 4 gas mixes per dive profile
• the depths are coded in 10 feet increments, the dive time in 1, 2, 5 or 10 min. increments
• via little pegs in a control board
• it is approx. from the beginning of the 1970's and was able
• to check the deco-obligations and as well it checked the ox-tox dose
  

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• This little drawing is from an US Patent of the year 1975!
• it is from Kirk E. Jennings, Kaneohe, Hawaii, US Patent No. 4005282,
• already that time with a trend-setting design:
  
  

• already around 1979 entered the Cyberdiver Series the american / canadian market
• this one is the Cyberdiver or resp. the XDC-3, the direct predecessor
• this is, worldwide, the first real divecomputer, i.e.:
• this box calculates via a microprocessor a full-blown decompression model in realtime under water!
• up to 4 h operation with a four(!) 9 V blocks, already a hose for a HP connection to the tank
• it displayed the tank pressure and the decompression status according to the canadian models
• more than 700 units were sold until the early 80's
• as well in 1979 there was the XDC-4 for mixgases up to 600 ft!
• It was a sophisticated Multi-CPU system and could handle different deco models: it did not make it to the market
• all these machines have been developped and built by DCIEM and CTF Systems, Inc.

• Already since summer 1977 (according to FACEPLATE) the USN had a little diver portable system
• it was called: Underwater Decompression Computer, UDC:
  

• it was used intensively in 1983 and 1984, especially to validate the new decompression model:
• the VVAL18, which is an E-L model for the UBA MK 15 / 16
• for us regular folks, who have not been diving in the USN:
• UBA = Underwater Breathing Apparatus, E-L = Exponential on-gassing, linear off-gassing,

• Sources for these Informations:
• Green, N. H., Woodward, B. The Evolution of Divers' Decompression Computers (1995), Society of Underwater Technology, Vol. 19, No. 1, p 9 - 23
• NEDU Report 1-63, R.D. Workman: Evaluation of a Decompression Computer developed for Divers
• NEDU Report 11-80, NAVY EXPERIMENTAL DIVING UNIT, REPORT NO. 11-80, TESTING OF DECOMPRESSION ALGORITHMS FOR USE IN THE U. S. NAVY UNDERWATER DECOMPRESSION COMPUTER, PHASE I Edward D. Thalmann, CDR, MC, USN
• NAVY EXPERIMENTAL DIVING UNIT, REPORT NO. 1-84, PHASE I1 TESTING OF DECOMPRESSION ALGORITHMS FOR USE IN THE U. S. NAVY UNDERWATER DECOMPRESSION COMPUTER Edward D. Thalmann, CDR, MC, USN, JANUARY 1984
• NEDU Report 10-86, TEST AND EVALUATION OF 2 PROTOTYPE MODEL UNDERWATER DECOMPRESSION MONITORS
• Microprocessor Applications to Multi-Level Air Decompression Problems, Karl E. Huggins, 1987, Michu-SG-87-201
• Proceedings of the AAUS Dive Computer Workshop, September 1988, USCSG-TR-01-89
• The Dynamcis of Decompression, Workbook, FIRST EDITION, KARL E. HUGGINS, THE UNIVERSITY OF MICHIGAN, ANN ARBOR, MICHIGAN, 1992
• Developing the NEW US Navy Tables (a copy from: aquaCorps Journal N8, p. 55 - 60)

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