[Oct/21/2005]


Dwarfs Den by Electro-Sport
http://www.arcadeflyers.net/?page=flyerdb&subpage=thumbs&id=3993


DD hardware is weird and complicated. There's no dedicated DMA controller
for CRT.  When serial output pin of cpu is in high state, all reads from
work RAM are redirected to CRT:

005B: 3E C0      mvi  a,$c0
005D: 30         sim
005E: E1         pop  h ; 40 times "pop h" = transfer 80 bytes (line) from ram to crt fifo
...
0087: 0F         rrc
0088: 30         sim

$4c00-$4fff part of work RAM is adressed in different way than other blocks. No idea why
(this part of the pcb is a bit damaged).
Gfx decode is strange - may be wrong.
Gfx rom bank (6d/6b or 6a/6c pair) is switched by timer circuit - few 74161 counters connected to xtal.
Current implementations is just a guess, and doesn't work on test screen.

                                               ______________
  _____________________________________________||||||||||||||_______________________________________
  |         1         2         3         4         5         6         7         8         9      |
  |                                                                                      ________  |
  ||| L                                                   SN7445N74  74LS224N  7404-PC   |9L    |  |
D |||                                                                                    |______|  |
  |||                                                                   _____________    ________  |
  ||| K                         BATTERY         16-1-471  7400-PC       | M5L8085AP |    |9K    |  |
  |                                                                     |___________|    |______|  |
  |                                                                                      ________  |
  ||| J           74LS273NA                     --------  --------             74LS373N  |9J    |  |
C |||                                                                                    |______|  |
  |||                                                                                    ________  |
  ||| H           74LS273NA  SN7442AN  74107N   74161N    SN7432N    M3-7602-5 MDP1603   |9H    |  |
  |                                                                                      |______|  |
  |                                                                                                |
  ||| F           74LS273NA  7408N     7486N    OSC       7404                 MM2114N   MM2114N   |
P |||                                                                                              |
  |||                                  _____________                                               |
  ||| E                      SN7442AN  |iP8274     |      7400       74LS244N  MM2114N   MM2114N   |
  |                                    |___________|                                               |
  |                                    _____________      ________                                 |
  ||| D 16-1-471  MDP1603    7414      |AY-3-8910  |      |6D    |   74LS245   MM2114N   MM2114N   |
B |||                                  |___________|      |______|                                 |
  |||                                                     ________   _______                       |
  ||| C 16-1-471  MDP1603    7414      7414     7400      |6C    |   |7C   |   M3-6514-9 M3-6514-9 |
  |                                                       |______|                                 |
  |                                                       ________   __________________            |
  ||| B SN74175N             74174N    74LS374N 74LS374N  |6B    |   |                |  6-1-471   |
A |||                                                     |______|   |                |            |
  |||                        _______                      ________   |    ______      |            |
  ||| A DN74505N             |3A   |   74153N   74153N    |6A    |   |    LM324N      |  DIP-SW    |
  |                                                       |______|   |                |            |
  |                                                                  |________________|            |
  |________________________________________________________________________________________________|

  OSC = 10.595 MHz
  D,C,A = 20-pin connectors
  B = 26-pin connector
  P = 12-pin connector (seems power)
  Edge connector (top) is not JAMMA
  3A (63S080N) dumped as 82S123
  7C = non populated

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