The Sinclair QL Forum

I like it. Congrats for successful development

For what the serial port?
Would not save resources (in this case) to use the Arduino Nano? for power and signal level compatibility.


The serial port is there mainly so that I can debug the USB HID (keyboard and maybe joystick) support via the ...

And the RS232 works... though when the board is powered by the PicoATX power supply the 74LS244 didn't get power as it seems that the Pico doesn't power the VBUS line if powered by VSYS, so a bodge wire was necessary.

The boards arrived just after lunch, so I quickly built one up. Just a minor issue with the DB9 sockets I bought overlapping one of the header positions, but nothing a pair of wire cutters couldn't fix.

The good news is that it works at least as well as the breadboard version so far. I've not ...

The OPD is not running QDOS and the OS treats the RAM as a set of 4K fixed size data pages in a database which it controls.

The machine is acting more like an early 1970s minicomputer than a micro.

My diagnostic ROM can do this, at least for memory up to 768K. I don't know what the memory map above that looks like and whether there's a risk that the memory test code might hit I/O ports etc. and give false reports of bad RAM.

What ever happened to this project?

The Telestore was also another target but I don't think anyone managed to read the EPROMs as they are soldered to the board?


It's on Github for everyone to enjoy. :-)

https://github.com/stephen-usher/OPD-Computer-One-Disk-Interface

The Telestore with the ...

You can read the two bytes which contain the 8 pixel group and then mask the value to determine of the bits are set.

Each scan line of the screen contains 128 bytes, or 64 pairs of bytes. In mode 4 each byte is a bit map of pixels, the first byte is red and the second green (from memory).

You ...

Over the last week I've been working upon a way of talking to a bare BBQL motherboard from another system.

Well, as of today I can do so with a prototype system...


IMG_4524.jpeg


Currently I can plug the Pi400 into the PIco's USB port and use minicom so that I can type on the machine as if I'm ...

Well, that's annoying... This is the output from J11 as seen by a logic analyser (ignore the labels)...


IMG_4516.jpeg


Not only do the output pulses overlap but they're not quite in order. The former part is the problem as I can't use them as a simple clock logic clocking the data out from the ...

If you don't want to buy the whole machine then there's a Spectrum case compatibleish PCB option for £150 or, if you have a KS1 Next, a replacement Next motherboard for £180. Might save you some pennies if you don't want the whole shebang.

Looks like the main differences between the KS2 and KS3 ...