The Sinclair QL Forum

Sorry for the delay

Yes , the interface is working ,

What i have changed since .......

7805 1 amp regulator , which is mounted on the copperside of the pcb .

The usb mouse must be "compatible" , i could not get the microsoft one to initialize properly , so after some testing a logitech M-BJ69 worked everytime i switched on the QL.


And not forget , it is not plug and play ofcourse .



techy

Hi All,

I would like to follow in the discussion as I am also interested in building this interface. I have studied the design, I'd like to ask as to which voltage regulator best to use.

Original design has 78L05, 5V, 100mA.
PIC is low consumption 2mA, multiplexers 4066 take micro Amps each, and mouse itself some 20 mA depending on the make.
Total current drawn by the circuitry is as I believe max. 20-30mA.

In terms of current 78L05 with 100mA should be enough, but how about dropout voltage, the data sheet says 1.7V

Does this mean the regulator has to be input with a voltage at least by 1.7V higher than the nominal output voltage 5V, correct?
But it is meant to be powered from the ROM port pin VCC 5V.

Please can anybody explain?

Many thanks

Tomas

flyer.gio wrote:I'm glad to share my last QL hardware project : The GC QL mouse adaptor.
This allow the use of a standard PS2/USB mouse with the QL.
It is connected to the QL via the CTL1 port (no hardware modifications are requested on the QL).
The 5V power come from a low power PSU or from the QL via the external ROM port.

A 78L05 is normally rated at 100mA
A 78M05 is normally rated at 500mA
Sometimes a 78M05 or 7805 is used instead of a 78L05 because they can disapate more heat.

The dropout voltage is the voltage across the regulator when it can no longer correctly regulate the output voltage as the input voltage falls. So if the input voltage drops below 5V+[dropout voltage], the output will fall below 5V.

For a 78x05 regulator, you should normally supply it with at least 7.5V so that the regulator has some headroom.

Mark

Mark,

Thank you for explaining.
What would be the voltage of VCC pin measured at ROM port?
If I decided to supply it from ROM port, am I safe to connect it to the regulator input, would not the output voltage be dropping too low for the circuitry?

Many thanks.

Tom

The ROM slot is fed with +5V downstream of the QL's 7805, to reduce component count and heat inside any external ROM cartridge. Since this is a post-regulator +5V, there is no need to include a regulator if taking power from there.

All you need is the expected decoupling caps.

If you are taking power from the QL ROM slot, that is a +5V supply, so no need for a voltage regulator.
If you are using an external supply, that's when you need the regulator.

Mark

Back in the early 90's I built my own mouse out of a Radio Shack TRS-80 Color Mouse. That mouse had a weird mechanism where it basically had potentiometers that would end at min and max, so I just wired the Control port cables for up/down/left/right plus space for the button. So it acted like a joystick but you had to move the mouse to neutral to get it to work properly. I briefly used it with ICE and it kinda worked. The mouse itself had a nice black matte plastic look that fit the QL.
I was reminded of the mouse I built when I saw a picture of this AT keyboard extension card for the ROM slot:
Anyone ever try to create a small foot-print ROM socket for PS-2 on the QL? Something like this (it's a not-to-scale mock-up I quickly created :-/):
Would be nice to be able to, at times, hook a keyboard up and just use the ROM socket as the means (and have there be a pass-through). I know there were a ton of other keyboard extensions out there that required all sorts of fiddling (daughter boards for internal chips, etc...) but a nice ROM plug-in with just a PS-2 port would be clean an elegant -- it worked for AT keyboards so is PS-2 much more complicated? And yes, that card was pretty big but I would suspect a modern rendition could be nice and small.

bwinkel67 wrote:Back in the early 90's I built my own mouse out of a Radio Shack TRS-80 Color Mouse. That mouse had a weird mechanism where it basically had potentiometers that would end at min and max, so I just wired the Control port cables for up/down/left/right plus space for the button. So it acted like a joystick but you had to move the mouse to neutral to get it to work properly. I briefly used it with ICE and it kinda worked. The mouse itself had a nice black matte plastic look that fit the QL.

That Tandy mouse looks very much like the Spanish StarMouse with its ball of iron. viewtopic.php?f=2&t=3061

bwinkel67 wrote:I was reminded of the mouse I built when I saw a picture of this AT keyboard extension card for the ROM slot:

I have one of those and it's all very well (but it actually only works - at least my type does - with the older/rarer XT keyboards). With it attached you have to plug the main QL ROMs into it. But the biggest issue for me is that it can't be used with the Tetroid device because the Tetroid renders the ROM port useless. It also requires a connection to the interrupt, so you do have to open the QL to solder that and to remove the ROMs. A bit fiddly. And then it sticks out of the back in a cumbersome fashion - it was mainly intended for custom case QLs with an internal backplane.

bwinkel67 wrote:Anyone every try to create a small foot-print ROM socket for PS-2 on the QL? Something like this (it's a not-to-scale mock-up I quickly created :-/):

ps2-rom-socket.jpg

Yes, but I wasn't able to fit the PS/2 support into the CPLD I used for my external QL-SD (https://www.kilgus.net/2020/03/28/ql-sd ... arly-days/). And if I had to include a µC then I'd probably go USB, but one thing at a time. Also, I'm mainly aiming at moue support.

Marcel

mk79 wrote:And if I had to include a µC then I'd probably go USB, but one thing at a time.

Oh, I thought USB was more difficult to support that's why I was asking about PS2. I would love a USB ROM-socket interface that allowed for keyboard/mouse support.