SwTPcMP-B2 board

The MP-B2 is the mother board in a 6800 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. Because these machines were often sold in the form of kits, the traces are each labelled, allowing one to see which signal is on which line.

There are only a few IC's on the board, but mostly just the male Molex connectors onto which the computer boards plug in. Here is a list of the IC's:

  1. 7805 (5v voltage regulator)
  2. NS 8835 [x2] (don't remember, will have to hit the databooks)
  3. 7400 (quad 2-in NAND)
  4. 7402 (quad 2-in NOR)
  5. 74S138 [x2] (three-to-eight line decoder)
  6. 74367 (hex tri-state buffer)

Below are lists of the names attached to each line.

MP-B2 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 - ground
  26. GND - ground
  27. GND - ground
  28. 7-8 VDC UNREG - power line
  29. 7-8 VDC UNREG - power line
  30. 7-8 VDC UNREG - power line
  31. -12V - power line
  32. +12V - power line
  33. INDEX - no pin - prevents backwards insertion
  34. *M.RST - manual reset
  35. *NMI - (complement) non-maskable interrupt
  36. *IRQ - (complement) interrupt request
  37. UD2 - user-defined
  38. UD1 - user-defined
  39. *Phase 2 (complement) clock
  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. Phase 1 clock
  45. *Halt - (complement) halts the processor
  46. 110b
  47. 150b
  48. 300b
  49. 600b
  50. 1200b

MP-B2 SS-30 Signals

  1. UD3 - user-defined
  2. UD4 - user-defined
  3. -12 - power line
  4. +12 - power line
  5. GND - ground
  6. GND - ground
  7. INDEX - no pin - prevents backwards insertion
  8. *NMI - (complement) non-maskable interrupt
  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. Phase 2 - (not complemented?) clock
  21. R/*W - Read / (complement) Write
  22. +8 UNR - power line
  23. +8 UNR - 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


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