The Sinclair QL Forum

Very impressive! Will you be able to make some kind of virtual microdrive that could replace the original one inside the QL?

vanpeebles wrote:Very impressive! Will you be able to make some kind of virtual microdrive that could replace the original one inside the QL?

That is the idea, using a small and cheap microcontroller.
Maybe the new LPC812 connected to a (micro)SDcard and a simple linear voltage stabilizer to create 3,3 Volt from the raw 9 Volt.
The LPC812 is a small but fully 32 bit ARM CPU with internal clock and PLL and runs at 30 MHz.
It needs very little power (less than 10 mA) and is 5 Volt tolerant on the IO pins.

To overcome the 255 sector limit there are several options:

• emulate multiple devices MDV1-MDV8 (still limited to about 8 * 100k)
• use for example MDV8 as communication channel to select images for the emulated MDV1-7
• Bootload a driver which can then access individual sectors via a new protocol over the MD bus

It's an exciting project which would be a great boost to the QL scene. Even a plain stock QL with no floppy drive or interface(the first problem new users come across) could be turned into a very usable machine with one(or both) of the microdrives replaced for one of these

gertk wrote:Well, result! Yes... My first directory generated by the mbed and recognized by the QL..
(snip)
Next step is to attach te sdcard to the mbed and get the sectors from there instead of my (huge) include file with the Quill MDV image...

Very interesting project - please keep us informed of progress. Good luck with your work on this device.

Connection to the SD card made, reading and writing works at the moment to a .MDV image file in the main directory of the (micro)SD card !

This sounds very promising! My favorite would be an external solution to be connected to the QLs MDV port on the right.

Yes - this looks good work - the main issue going forward is going to be to try and get around the 255 sector limit.

I would also aim to have this as a replacement which could fit in either the QL's microdrive slots, or a ZX Spectrum microdrive unit - that would open it to the widest possible market!

RWAP wrote:Yes - this looks good work - the main issue going forward is going to be to try and get around the 255 sector limit.

I would also aim to have this as a replacement which could fit in either the QL's microdrive slots, or a ZX Spectrum microdrive unit - that would open it to the widest possible market!

I am already thinking of some ways to do this:

* emulate multiple MD images (still limited to 255 sectors) Images for MDV3 up to 7 could be selectable by sending commands to for example MDV8 (by using GET/PUT)

Getting around the 255 sector limit is only possible by bypassing the original driver after booting from a normal Image.

* Bootload a driver which can handle direct sector requests and is not limited to 255 sectors

The latter option would also speed up loading and saving because you don't have to wait for the virtual tape to go round.

Given the limitations of microdrives, if you're replacing the hardware that sits in the microdrive bays ANYWAY, why not use a floppy driver-based system? Given the extra simplicity and reliability, and roughly equal cost, it's an easier development path.

This is a cool project though.

From this point of view, the ideal peripheral device was the ROMDisq (four expansion ROMs, e.g. Toolkit II, and flash-memory based storage). Pity, it was limited to 4 MB.
With larger space on flash, or with SD card, this will be unbeatable expansion.