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• Here how 600 dg403dy look like

  Dmitry V. Sokolov • 12/20/2017 at 06:22 • 0 comments

  Some of them have 1990 on the label :)

• More on ternary memory (flip-flap-flops)

  Dmitry V. Sokolov • 12/19/2017 at 11:50 • 0 comments

  A flip-flap-flop can be made from two static memory cells wired in a master-slave configuration. Here is the schematics and accompagnying video:

  I use exactly this schematic in the program counter. The RAM is wired a bit differently, however the idea is the same. 

• Balanced ternary DAC

  Dmitry V. Sokolov • 12/19/2017 at 11:27 • 0 comments

  I'd like to play pong on my computer and I plan to use an old scope in the X/Y mode for the screen. So I need a digital-to-analog converter. Naturally, resistor ladders come into mind, however R-2R would not work directly.

  Let us try to find resistor values. Current intensities are tied with the voltages in the following way:

  You can try the following code snippet in the sage calculator:
  

  var("R,R1,R2,R3,R4,R5,R6,V1,V2,V3")
  A=matrix([[0,0,1,-1,0,0],[0,1,0,1,-1,0],[1,0,0,0,1,-1],[0,0,R3,R4,R5,R6],[0,R2,0,0,R5,R6],[R1,0,0,0,0,R6]])
  b=matrix([[0],[0],[0],[V3],[V2],[V1]])
  I=(A.inverse()*b).simplify_full()
  
  Vo=(I[5][0]*R6+I[4][0]*R5+I[3][0]*R4).simplify_full()
  Vo=Vo.substitute(R1==R,R2==R,R3==R)
  
  eq13=(26/27==Vo.substitute(V1= 1,V2= 1,V3= 1))
  eq12=(24/27==Vo.substitute(V1= 0,V2= 1,V3= 1))
  eq11=(22/27==Vo.substitute(V1=-1,V2= 1,V3= 1))
  eq10=(20/27==Vo.substitute(V1= 1,V2= 0,V3= 1))
  eq09=(18/27==Vo.substitute(V1= 0,V2= 0,V3= 1))
  eq08=(16/27==Vo.substitute(V1=-1,V2= 0,V3= 1))
  eq07=(14/27==Vo.substitute(V1= 1,V2=-1,V3= 1))
  eq06=(12/27==Vo.substitute(V1= 0,V2=-1,V3= 1))
  eq05=(10/27==Vo.substitute(V1=-1,V2=-1,V3= 1))
  eq04=( 8/27==Vo.substitute(V1= 1,V2= 1,V3= 0))
  eq03=( 6/27==Vo.substitute(V1= 0,V2= 1,V3= 0))
  eq02=( 4/27==Vo.substitute(V1=-1,V2= 1,V3= 0))
  eq01=( 2/27==Vo.substitute(V1= 1,V2= 0,V3= 0))
  
  sln=solve([eq01,eq02,eq03,eq04,eq05,eq06,eq07,eq08,eq09,eq10,eq11,eq12,eq13],R4,R5,R6)
  show(sln)

  Turns out that it is not R-2R. It is R-2R-4/3R! Let us plug my 3-trit counter to the resistor ladder:

  The sawtooth wave clocks the counter, and we have a nice staircase output. With few spikes, but those are easy to filter out.

• I/O board

  Dmitry V. Sokolov • 12/19/2017 at 11:16 • 0 comments

  On my photos you will often see the FR-2 brown board, I guess it would be good to show how it works.

  It has 9 lines that can be used both as input and output, here is the schema of one i/o line:

  So the board has 9 single pole triple throw slide switches connected to -5, 0 and 5V. When the switch is in the middle position, the line reads voltage. The common collector amplifier is an overkill here.
  

  Here is the layout of the board:

  In fact, this is exactly the circuit I have in my program memory, but it can be used for reading signals too.
  

• Random access memory

  Dmitry V. Sokolov • 12/15/2017 at 16:15 • 0 comments

  To build a single edge triggered flip-flap-flop I need 4 ternary multiplexers.

  It means that I need 2 trimux boards per trit to store. These are two 3-trit memory cells, therefore 12 trimux boards (6 boards per cell).

  TRIADOR will have 13 3-trit memory cells in total, let me show you the RAM board:

• It is Christmas soon!

  Dmitry V. Sokolov • 12/15/2017 at 14:08 • 0 comments

  My Christmas decoration: 

  This how the program memory looks like. Those are single pole triple throw slide switches. For the sake of visibility the position of the switches is highlighted with bi-color LEDs. Red light = -1, no light = 0, green light = 1.

  The opcodes have 5 trits, so I have 27 5-trit instructions per memory segment. One memory segment is composed of 5 copies of this circuit:

  Given a 3-trit address (hi,mi,lo), the 1:27 multiplexor (made with 5 1:3 multiplexers) provides one trit of the corresponding opcode. Thus one memory segment can be seen as a black box that receives a 3-trit address and provides a 5-trit opcode.

  Here I have soldered 2 program memory segments, 54 instructions total. The architecture supports up to 27 memory segments (27*27=729 instructions).  

• Ternary memory latch

  Dmitry V. Sokolov • 12/15/2017 at 10:14 • 0 comments

  WIth two multiplexers (one trimux board) it is possible to build a memory cell:

• Nixie tubes display for the ternary counter

  Dmitry V. Sokolov • 12/15/2017 at 10:04 • 0 comments

• Program counter

  Dmitry V. Sokolov • 12/15/2017 at 09:54 • 0 comments

  Our computer needs a program counter. So we start with a schema:

  Test it on a breadboard:

  And here is the final program counter that will drive the TRIADOR:

• Building blocks are ready

  Dmitry V. Sokolov • 12/15/2017 at 09:48 • 2 comments

  As I said, the only building block allowed is a ternary multiplexer based on DG403 analog switches. With two DG403 it is possible to build a circuit bearing two ternary multiplexers:
  

  Here is the layout:

  The total budget for this project is set to 300 trimuxes or 600 ternary multiplexers. Here are all the components soldered, cleaned and tested:
  

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