The Sinclair QL Forum

possible issue with the edge connector (like a pin that's bent and shorting out maybe?)

ah - so the JM and Minerva ROM's are in 2 different QL's ?

The only possibility I can think if is if your Minverva also has TK2, and the floppy interface is set for the ROM port address...

Nice one

Well done on the progress with the DRAMS - so now probably just a single faulty chip?

The QL motherboard has pin 1 and pin 28 wired to 5V - so the 'expected' A15 signal is not on that pin - instead it's used as a chip select for the ROM's - the ROM's in the QL ROM set - one is active high and one active low - so A15 decodes whether lower 32K or upper 16K rom are selected. Either ROM ...

that could be down to either a ram chip not being writable (Data in on the RAM shorted or open circuit), or to a shorted or open address line on the DRAM chips - the regular pattern also suggests something like this. Such problems are hard to find. As you have surmised - the upper and lower banks ar...

those current draws are favourable. Letterbox - just that a keyboard and LCD screen combo may be a good way to do this - as it's one single case to make - no hinges. The letterbox LCD screens are available with HDMI input - but the resolutions are a bit strange - they are usually 400x1280 or 480x192...

Thoughts from the 40th QL Celebration. It was a late decision for me to attend the 40th Anniversary celebration in Dormagen, but I am glad that I did make that decision. Having been in and out QL ownership over most of those years, but strangely always having a couple of Sinclair products in my hous...

I've used 7V without a problem, not sure about 7.5V - It is dropped by one diode forward voltage (about 0.6-0.7 vols), and feeds the circuit that would normally see the 6V from the batteries. Very fresh batteries could provide close to 1.6V each - giving a voltage of 6.4 against the 6.9 you would se...