SwTPcMP-B3 board

The MP-B3 is the mother board in a 6809 system. It has a set of fifty parallel traces to carry the signals of the SS-50 bus, and another set of thirty for the SS-30 I/O bus. Probably as a legacy of their earlier systems which were sold as kits, the traces are each labelled, allowing one to see which signal was on which line.

There are a few IC's on the board, but mostly just the male Molex connectors onto which the computer boards would plug in.

Below are lists of the names attached to each line. Note that the meaning of S1 through S4 are dependant on the configuration of the other boards. With one setup, these are four address lines, bringing the address space up to a Megabyte. With the other setup, these four lines carry baud rates.

MP-B3 SS-50 Signals

  1. *D0 - (complement) data bus line 0
  2. *D1 "
  3. *D2 "
  4. *D3 "
  5. *D4 "
  6. *D5 "
  7. *D6 "
  8. *D7 - (complement) data bus line 7
  9. A15 - address bus line 15
  10. A14 "
  11. A13 "
  12. A12 "
  13. A11 "
  14. A10 "
  15. A9 "
  16. A8 "
  17. A7 "
  18. A6 "
  19. A5 "
  20. A4 "
  21. A3 "
  22. A2 "
  23. A1 "
  24. A0 - address bus line 0
  25. GND power line
  26. GND "
  27. GND "
  28. +8V "
  29. +8V "
  30. +8V "
  31. -16V "
  32. +16V power line
  33. index-slot - no pin - prevents backwards insertion
  34. *Memory Ready
  35. *BSY/*NMI - (complement) non-maskable interrupt
  36. *IRQ - (complement) interrupt request
  37. *FIRQ - (complement) fast interrupt request
  38. *Q - (complement) the "quadrature" clock signal
  39. *E - another clock signal
  40. *VMA - (complement) Valid Memory Address
  41. R/*W - Read / (complement) Write
  42. *Reset - (complement) Reset or power-up
  43. BA - Bus Available for DMA
  44. BS - ???
  45. *Halt - (complement) halts the processor
  46. *Bus Req - (complement) bus request
  47. S3 - either a baud rate (which?) or A19
  48. S2 - either a baud rate (which?) or A18
  49. S1 - either a baud rate (which?) or A17
  50. S0 - either a baud rate (which?) or A16

MP-B3 SS-30 Signals

  1. RS2 - register select 2 - like A2
  2. RS3 - register select 2 - like A3
  3. -16V power line
  4. +16V "
  5. GND "
  6. GND power line
  7. index-slot - prevents backwards insertion
  8. *FIRQ/Q
  9. *IRQ - (complement) interrupt request
  10. RS0 - register select 0 - like A0
  11. RS1 - register select 1 - like A1
  12. D0 - data bus line 0
  13. D1 "
  14. D2 "
  15. D3 "
  16. D4 "
  17. D5 "
  18. D6 "
  19. D7 - data bus line 7
  20. E
  21. R/*W - Read / (complement) Write
  22. +8V power line
  23. +8V power line
  24. 1200b - 1200 baud clock signal
  25. 4800b - 4800 "
  26. 300b - 300 "
  27. 9600b - 9600 "
  28. 110b - 110 baud clock signal
  29. *Reset - (complement) Reset or power-up
  30. Board Select

17-Feb-1999
yakowenk@csx.unxc.edu
(remove all "x"s to get a valid address)