jumper JP3 sets 768 (1-2) or 832 K (2-3) bytes total memory.
When JP3 is set to 1-2 (768K) then Qubide rom must be placed at address E0000h
( SV2 I I I : : )
When JP3 is set to 2-3 (832K) then Qubide rom must be placed at address F0000h
( SV2 I I : : : )
SV4 is used to place a card connected to the expansion connector to the correct slot by setting the SP0..SP3 to high or low level.
"The position of each peripheral device in the overall memory map of the QL is determined by the select peripheral lines: SP0, SP1, SP2 and SP3. These select lines generate a signal corresponding to the slot position in the QL expansion module, thus for a device to be selected the address input from address lines: A14, A15, A16 and A17 must be the same as the signals from SP0, SP1, SP2 and SP3 respectively."
When using 832K SP01..SP03 should be in high level so connecting pin 2,3,4 and pin 6 of SV4 takes care of this.
In practice I noticed that when no connection is made my floppy controller card reads the SP0..SP4 as high level so no problem but it is better to populate the R1 with 4.7K and connect pin 6 to pin 2,3,4 if you intend to connect another card to the expansion connector. Pin1 may be connected to gnd (pin 5).
Use a low profile ide cable and cable connector (maybe just the pins without the plastic) because the card won't fit the height to enter in the ql and you will need to open the case to fit it and then close it again.
You may also use a 90 degree angled ide connector that solves the height problem but then you won't be able to add the expansion connector to use another card so it's convenient if you don't plan to use this qubide clone with another card. In this case you can connect a flash card board directly on the card without using a cable.
This card must be the first connected to the QL.