The Sinclair QL Forum

Hmm, that doesn't match what i've read so far. Tapes hold ~220 sectors with 512 Bytes each. These are 112640 bytes or 901120 bits (ignoring any headers and GAPs). Reading all of them in 7.5 seconds would result in a bit rate of more than 120 kbit/s. The real value will be even higher due to gaps and ...

BTW: How long does a random sector access take at most? 100k+overhead at 100khz should be something over 10 seconds. Is that correct?

Emulators typically first try to mimic the original machine perfectly and on top of that start to implement add-ons. That's why I'd like to add a microdrive to my hdl implementation as well. I'd really like to see something that gives me the original feeling.

Yesterday i made my HDL implementation ...

I meant the 174930 byte images. That's the qlay format?

It seems a little odd that microdrive images are barely used in emulation.

Thanks again. Very helpful!

Looking at the 174930 bytes drive image i see some differences:

- There's another 10*0+2*ff preamble before the header and the data
- nml seems to be 10
- there's another 2 bytes at the end of the header. Perhaps a checksum? You header does not have one which is hard to ...

While working on the HDL QL i had to understand the keyboard encoding. Here it is.

Sinclair QL keycode table Till Harbaum V1.0 - 08/04/2015
-------------------------------------------------------------------------

This table shows how the 64 keys of the Sinclair QL are wired and how their
codes ...

3. wait for a gap interrupt
4. start reading from $18022/$18033 - if it's a header, check for sector #21
5. goto (4) if it's not the correct sector header (basically wait for sector header #21 to come by)


Really go back to 4? Not to 3?

Also is there also a gap between the sector header and the ...

Thanks again. That all makes sense and shouldn't be too difficult to implement.

I think I have a working 50hz irq. I'll have a look at this on monday. I can watch the cpu inside the fpga running using signaltap. So it'll be possible to see why the cursor is not there ....

Excellent information. Especially about the interrupt register.

I have some basic keyboard stuff running and f1 and f2 now sort of work and I can get to the main screen.

I am still missing information on the bit 3 in the first nibble returned in the answer to ipc command 8. This seems to be 1 on ...

Hi,

the MESS sources actually contain the best explanations i've seen so far:
https://github.com/mamedev/mame/blob/master/src/mess/machine/zx8302.c

Doing IRQ handling the way these comments suggest seem to be ok. Next will be to decode the IPC requests to be able to reply with keycodes. In the end ...