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Hacking Interfacing the Boxford 190VMC


Long ago this CNC was controlled by a BBC Master from Acorn.

I just found a disk with the software used to control the Boxford 125 tcl lathe that happens to have a very similar electronic board as the 190VMC. To emulate the BBC master on a Windows7 sytem I have used "BeebEm 414"---> and the disk can be downloaded from here:

It could be a starting point for decoding the initial handshake to control the drivers. The documentation suggests that it uses standard gcode (ISO)--->

Yesterday I was able to connect to the cnc via serial(b:9600 d:8 s:1 p:none) and get its model but could find any code that actually moves the motors.


DataSheets for the existig electronics

  • DS80C310 High-Speed Microcontroller, driving each motor:

  • Lense Speed controllers 530 series Spindle:


  • microstepping

  • Serial cabling db25 and db9

[[parallel_port_pinout.jpg ]]

The cnc sends 5 blocks of 7 chars, the structure as follows:

P000000// Z axis
p000000// feed rate
 s 0000// spindle rpm
00000E5// X axis
@000000// Y axis

Null modem cable with loop back handshaking does not make any difference when sending regular GCode


I was able to make the cnc move by sending 7 nibbles(each one with #A) and then gcode although it is not really stable.


line00: AA AA AA A \CR (hex)                    1010 1010 1010 1010 1010 1010 1010
line01: G00 X05 \CR (ASCII)

line00 needs further investigation as each bit should be enabling something on the uC

must be worth it to read from the eeprom



Software controller sends "=" (asci) 3D (hex)before sending the actual gcode and then it waits for the CNC to:

  • Reset
  • Cancel Manual mode
  • Press both + and - axis buttons for each axis.