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Microbee Add-on boards

Additional functionality could be added to some Microbee models though optional add-on boards.
 

Standard Colour option

This is a colour board option for Standard model Microbees with a 3.375MHz CPU clock. It provides 32 foreground colours determined by IC 7 (a PROM) on the colour board and up to 64 different background colours although only 8 different combinations of background colours are possible at any one time.
 

Board Number Board Colour Component Side Image Solder Side Image
  • Notes
MB1217 Type 1
  • Provides both digital and analog output signals.
  • Some schematics are marked as "standard" (digital).
  • Drawing Numbers: MB1217 (D) and MB1217 (AD).
MB1217 Type 2
  • Provides both analog output signal only.
  • Some schematics are marked as "analog".
  • Drawing Numbers: MB1217 (D) and MB1217 (AD).
1217-54-09W Green 1217-54-09w_top 1217-54-09w_bottom
  • Picture shows fitted to underside of 1248-4-02W mainboard. Would need de-soldering to remove.

 

Viatel upgrade option

This board option allowed the use of Viatel software (followed by Videotext later) to provide the 40 character wide screen mode.
 

Board Number Board Colour Component Side Image Solder Side Image
  • Notes
8346-1-03CR Green 8346-1-03cr_top 8346-1-03cr_bottom
  • Un-populated board. See its Manual for construction and fitting.

 

Real Time Clock option

This board option allowed Standard and early Premium models to have a Real Time Clock (RTC).
 

Board Number Board Colour Component Side Image Solder Side Image
  • Notes
8335-2-01

 

50 Way Expansion Kit

This is an add-on board designed for Standard models. It provides a 50 way Expansion Interface for connecting external peripherals and also provides video de-glitch functionality. The two functions are not related to each other and may be independently and optionally implemented during installation. The 50 way interface is identical to that normally provided by Static RAM (SRAM) Core boards and may be used to provide a second interface for those machines. The board is particularly useful for adding expansion capability to models that are fitted with Dynamic RAM (DRAM) Core boards since these do not incorporate a 50 way interface.

This board is installed beneath the Standard Main board and connects via an extended pin/socket arrangement as well as requiring a set of separate fly wires. See the 50 Way Expansion Kit Manual for construction and fitting details.
 

Board Number Board Colour Component Side Image Solder Side Image
  • Notes
8342-3-04CR Green 8343-3-04cr_top 8343-3-04cr_bottom
  • Picture shows fitted to underside of 1248-4-02W mainboard. The component side is viewed by unplugging the board and swinging to the side, no de-soldering is required.
  • The board pictured here is fitted with video de-glitch circuit components but this function has not been implemented during installation.