Acorn Products Z80 SECOND PROCESSSOR 409 用户手册

"BBC Microcomputer 32k..." message displayed.

Predominantly caused by either power failure, misconnected or 

damaged plugs and/or interconnecting cable.

"Acorn TUBE Z80 64k ..." message displayed; no response to 

Keyboard.

If  this  message  is  displayed,  the  ROM  has  been  copied 

completely  to  RAM  ,  the  ROM  disabled  and  the  Boot  procedure 

begun.  Failure  to  respond  to  the  keyboard  means  that  the 

system has crashed due to either hardware or software failure. 

Possible causes may be:

Software

Hardware

Incompatible or failed

Tube register fault

DNFS or Boot ROM

Z80 fault 

DRAM error

A further consideration is that a component or components may 

have 

become 

temperature 

sensitive 

and 

are 

failing 

intermittently.  Check  by  first  replacing  IC1,  1C2  and  IC3  in 

turn,  then  check  operation  once  warm;  use  a  freezer  spray  to 

locate temperature-sensitive components.

Flashing Cursor in the top left corner of an otherwise blank 

screen (Total Failure)

This is the most usual result of plugging in a broken Z80 

second processor as the majority of

faults manifest 

themselves in this way.

Normal Operation until BREAK reset attempted; system fails.

Most probably caused by failure of reset circuit (IC15b, 

IC14 and associated components).

BBC Microcomputer fails when Z80 Second Processor connected to 

Tube socket

Probable  causes  are  misconnected  or  damaged  plugs/sockets 

and/or damaged ribbon cable; Tube IC failure or IC29 failed on 

Z80 PCB.

Diagnostic  Flowcharts  for  the  above  conditions  are  given  in  the 

Appendix.  These  should  be  read  in  conjunction  with  the  following 

Circuit Checks: