Floppy Drives with TrumpMini3 Woes

[t0nyt]

You have to be careful sometimes. It's quite possible that one machine code program is reloading another, and in that case, the absolute file path is already included in the code, e.g., "mdv1_something_cde." Unfortunately, a new image won't help in that case.

Have got most of my games running ok from QIMSI (some needing the folder substituted to appear as FLP or MDV). It's mainly the few that need pretty much all of 128KB, but don't like more, that I run from FLP/MDV

It's fun trying to get them to run (modified or unmodified) from QIMSI, but sometimes it's not worth the effort or seemingly impossible

My plan to have a boot file on vDrive that initialises the MT3 Trump ROM has worked ok too, just not ideal

Am wondering if I could make a simple board to sit between QL and QIMSI with a switch to disable it rather than wearing the contacts on the QIMSI or SD Card

[Dave]

Put the switch on the ROMOEH line and the port will never be selected. Everything else just passed through.

While you're at it, you could place the socket pointing up so the card slots are sticking up behind the QL instead of 2cm further backward. A new 3D printed case would blend right in and be much more slimline.

[t0nyt]

Put the switch on the ROMOEH line and the port will never be selected. Everything else just passed through.

While you're at it, you could place the socket pointing up so the card slots are sticking up behind the QL instead of 2cm further backward. A new 3D printed case would blend right in and be much more slimline.

Thanks Dave

Do you mean the switch should just be in series, to make/break the ROMOEH line please?

Many thanks
Tony

[t0nyt]

Have found a simple alternative it seems

I've found my little SD card extension unit which means I can avoid wear and tear on the QIMSI SD Port & SD Card

Turns out I only have 2 games that needed the QIMSI itself removed when I went back thru the list

And have now resolved QL Hyperdrive so it only needs the SD card, not the whole QIMSI, removed

Just one more to try and sort (Sam the Little Spaceman)

Thanks
Tony

[t0nyt]

Would I be correct that the pin highlighted by the (rather large) arrow is the ROMOEH line please?

If so, is it the upper or lower pin please?

Many thanks
Tony

P1012029.JPG (40.03 KiB) Viewed 298 times

[Dave]

The outer pin on row B is indeed the ROMOEH pin.

[t0nyt]

The outer pin on row B is indeed the ROMOEH pin.

Thanks Dave

So in theory I could cut the leg and fit a switch across to give me a way to enable/disable the ROM port please? The extra wire wouldn’t cause any timing/whatever problems please?

Many thanks
Tony

[Dave]

That’s correct.

The signal is active high. This is perfect as disconnecting it with a switch negates the signal. I’d add a resistor to limit current so the switch doesn’t act as a direct short to ground. Limiting the current would protect your hardware. A 100 ohm resistor should be enough. Maybe higher.

Active low signals would be negated by pulling them up to high. That’s more tricky as you have to disconnect the line and apply 5v to the device side but not the CPU side.

[t0nyt]

I’d add a resistor to limit current so the switch doesn’t act as a direct short to ground. Limiting the current would protect your hardware. A 100 ohm resistor should be enough. Maybe higher.

Thanks Dave

To be honest with my lack of knowledge on electronics I can’t claim to understand where the resistor should be in the circuit please?

Also is 100 ohm = 100R please?

Sorry for the dumb questions!

Many thanks
Tony

[Dave]

100 ohms is 100R, yes.

Obtain a single pole double throw switch. It has three pins. The middle one goes to the ROMOEH pin on the QIMI card. The left one goes to the ROMOEH pin on the ROM port (the QL side). The right side connects to GND.

If the switch is slid left, the QIMI receives ROMOEH signals and can operate. If it is to the right, ROMOEH does not get through and the pin is always low (negated). The QIMI is never addressed.

It still has access to power so it will not be damaged by having power applied to other pins. Anyone thinking of disabling the AIMI by turning off the power line, this is a very bad idea. QIMI's tolerance to voltages on pins is going to be very reduced if the chips are unpowered. I'm fairly sure this is a situation that wasn't considered in the design.

I'm working right now, but this evening I will publish the board and schematic on EasyEDA so anyone can order PCBs and assemble one.