Retro Challenge - 2015/07 - Day 5

Installed SD Card

Dismantled the Compact and installed the GoSDC into the ROM slot.

TV Display

Tried to power the small TV display from the machine but found it requires 6v. Going to have to add another Step-Up to the power board to provide the 6v it requires.

Update: Wired in the extra Step-Up, Adjusted the voltages on the Step-Up boards so that one is 5v and the other 6v.

Connected the power board to the BBC externally and checked that everything works ok. Board is powering the screen, Gonbez board and the BBC from the battery.

Then tested the TV board, connected to the external video out and got the following.

You can just about make out the Acorn MOS and the command prompt. This looks better in real life the camera doesn't do it justice. Next step is to get it to run something on the screen.

Retro Challenge - 2015/07

The Problem...

I currently have a BBC Master setup on the desk in my office. The problem is that its not very portable, if I want to take it anywhere it requires a large CRT monitor or my recently acquired Gonbes VGA convertor board, a modern monitor and a set of power supplies.

You then also need to take either a disc drive or the DataCentre to give me access to disc images so that I can actually do anything.


I have a spare BBC Master Compact which I intend to make much more portable.

To do this I intend to add the following to the machine...

1) As the original BBC Master Compact uses a large desk unit to house the disk drives I need an internal method of storing software to run on the machine.

So I bought a GoSDC board which adds an SD card allowing me to store all of the software I need to use. The device plugs into a spare ROM socket internally in the machine.

John Kortink who designed the board was kind enough to supply one without the headers as he thinks the Compact may not have enough room inside with them attached. If this is the case I will need to wire a set of switched to the board to enable and disable it for updating the firmware.

2) So that I can run the machine away from any kind of power supply I want to add an internal rechargable battery.
Probably a lithium one with a charging circuit to provide a few hours of usage without needing a power supply. Obviously when the power is supplied it should cut off and charge the battery instead.

As part of this I will add in a power switch so that the machine can be easily turned off and will allow for charging without the machine being powered up.

3) To provide a VGA output I will fit the Gonbes board internally and provide a VGA socket on the back for connecting an external monitor.

This will require the power to the board and the TTL RGB output from the BBC to be wired to the board,

4) So that I can use the machine while on battery and without a VGA monitor or TTL RGB one I intend to provide a small screen built into the machine. This will probably be a 3-5 inch screen added to the top area of the case. Depending on the screen type this will either be wired to the composite out or to the second port on the Gonbes board.

This should be a mirror of what is output to the VGA / TTL RGB. I might put a switch in to be able to turn it off as it will display even when connected to an external monitor. If I have time it would be cool if when the external monitor is connected it displayed a cool logo.