It's good to hear your system is booting.
The original kit microbees were powered using a 12VAC plugback to provide a negative voltage for the serial port and hence had a large filter cap and diode bridge on the baseboard to derive the 10VDC. This was changed to a 10-12VDC power supply to minimise 50Hz mains hum affecting the video output signal with the serial port losing its negative voltage. This new configuration meant that a smaller mainboard filter capacitor could be used because the main filtering cap and the diode bridge was in the external power supply. When switch mode power supplies are used the filtering cap may be further reduced as not to present transient short circuit upon power up. The single 1.5A TO-3 voltage regulator was replaced with 2 x TO-220 1A regulators which used the keyboard bracket as a heatsink. The single 5V rail on the baseboard was split into 2 separate ones - one for each voltage regulator. The diode bridge was replaced with an inline polarity protection diode. (These days we could use a MOSFET)
Someone didn't have much documentation on the Colour board.
The colour daughter board was just a tacked on the baseboard using wirewrap sockets, a few PCB mods and patch wires. (Not dissimilar to how the S100 TCT PCG was tacked on to the S100 DG640 VDU).
It is a horrible thing - particularly to repair.
In addition to colour capability, a video memory contention circuit was added to remove the annoying black flickers however this introduced CPU wait states so the firmware needed the appropriate adjustment for bitbashed functions such as Tape, Serial and Spaker. (The colour contention circuit was later redesigned twice - once as a motherboard revision for standard bees and another for the Alpha Plus (Premium Series). Implemented with Monostable Multivibrators with an RC network, the trimmer resistors are adjusted so the flickers disappear.
MW Colour BASIC also introduced a new COLOUR/COLOR statement but it isn't actually implemented as a tokenised keyword. It's handled in a quite different manner and can handle either spelling.
The original kit microbees were powered using a 12VAC plugback to provide a negative voltage for the serial port and hence had a large filter cap and diode bridge on the baseboard to derive the 10VDC. This was changed to a 10-12VDC power supply to minimise 50Hz mains hum affecting the video output signal with the serial port losing its negative voltage. This new configuration meant that a smaller mainboard filter capacitor could be used because the main filtering cap and the diode bridge was in the external power supply. When switch mode power supplies are used the filtering cap may be further reduced as not to present transient short circuit upon power up. The single 1.5A TO-3 voltage regulator was replaced with 2 x TO-220 1A regulators which used the keyboard bracket as a heatsink. The single 5V rail on the baseboard was split into 2 separate ones - one for each voltage regulator. The diode bridge was replaced with an inline polarity protection diode. (These days we could use a MOSFET)
Someone didn't have much documentation on the Colour board.
The colour daughter board was just a tacked on the baseboard using wirewrap sockets, a few PCB mods and patch wires. (Not dissimilar to how the S100 TCT PCG was tacked on to the S100 DG640 VDU).
It is a horrible thing - particularly to repair.
In addition to colour capability, a video memory contention circuit was added to remove the annoying black flickers however this introduced CPU wait states so the firmware needed the appropriate adjustment for bitbashed functions such as Tape, Serial and Spaker. (The colour contention circuit was later redesigned twice - once as a motherboard revision for standard bees and another for the Alpha Plus (Premium Series). Implemented with Monostable Multivibrators with an RC network, the trimmer resistors are adjusted so the flickers disappear.
MW Colour BASIC also introduced a new COLOUR/COLOR statement but it isn't actually implemented as a tokenised keyword. It's handled in a quite different manner and can handle either spelling.