____________________________________________________________________
UHT |  _______   ____      ____     ____    ____    ____    ___________  |
OUT_|_|       | |____|    |____|   |____|  |____|  |____|::| BASIC ROM | |I
  |_ _| ASTEC | |____|    |____|   |____|  |____|  |____|  |___________| |I T
    | |UM 1233| |____|   :|____|   |____| I|____|   _____  |           | |I U
VID | |_______| |____|    |____|   |____| I|____|  |_____| |___________| |I B
OUT_|_          |____|    |____|   |____|   _____  |_____| |           | |I E
  |___|           ____    |____|   |____|  |_____| |_____| |___________| |I
    |            |____|   |____|    ____   |_____| |_____| |           | |
RGB_|___    _     ..               |____|   ___________    |___________| |
  |_|   |  | |    ____     ____     ____   |           |:  |  O/S ROM  | |I 1
    |   |  |_|   |____|   |____|   |____|  |___________|   |___________| |I M
   _|   |   _                       ___________   _____        _____     |I B
RS|_|   |  | |    ____     ____    | 5050 2186 | |_____|      |_____|    |I U
423 |   |  |_|   |____|   |____|   |___________| |_____|      |_____|    |I S
   _|   |  ---   _______________   _______________   _______________     | 
  |_|___| |   | |      6845     | |      8325     | |      8303     |    |  U
CAS |  ____---  |_______________| |_______________| |_______________|    |I S
    | |____|                                                             |I R
    |    ___________   _________     ____    ____    ____    _____       |I P
    |   |    8314   | |   8319  |   |____|  |____|  |____|  |_____|      |I R
    |   |___________| |_________|                  ...  ..               |  T
ANLG|___                   I         ____    ____    _::_     ____       |
IN _|   |  ___________     ____     |____|  |____|  |____|   |____|      |
  | |   | |    7002   |   |____|                              ____       | 
  |_|   | |___________|    ___I      _______________ I ____  |____|      |I P
    |___|                 |____|    |      8305     |I|____| |_____|     |I R
    |                ____ |____|    |_______________|I ____   ____       |I N
    |               |____| ____                      I|____| |____|      |I T
    |                ____ |____|     _______________ I ____   ____       |I E
    |               |____| ____     |               |I|____| |____|      |I R
    |                ____ |____|    |_______________| |____|    __       |
    |               |____| ____          ___________   ____    |__|   I  | 
    |                     |____|        |           | |____|             |I D
   _|                                   |___________|                    |I S
   _|                                I   ___________   ____              |I C
ECO |                                 I |           | |____|             |I D
NET |   __                      ____    |___________|         ____       |I R
    |  |__|                    |____|                 I      |____|      |I V
    |____________________________________________________________________|
    |                                                  |                 |
   _|                  POWER SUPPLY                    |___              |
  | |                                                  |   | AUX POWER   |
  | |    ==========================================    |___|  OUTPUT     |
ON|_|    = Acorn BBC Microcomputer Model B (1981) =    |                 |
OFF |    =  Motherboard layout by David Wooding   =    |                 |
____|    =    Key:  III connectors ::: jumpers    =    |                 |
____|    ==========================================    |                 |
    |__________________________________________________|_________________|