The Sinclair QL Forum

Yes, one on should be able to implement DTACK.
Also there are two 74HC04 in there, one of which has 2 unused inverters, and the other has 3.
The one with 3, uses 2 for the floppy WD1772 clock and one to invert the RDWL signal for the ROM. If an integrated 8MHz oscillator is used, two of those ...

Using an 8 MHz clock oscillator saves one IC, two resistors and some space on the board...
It should be possible to also remove 4 diodes and make the whole thing faster with a few changes to the GAL programming, will look at the source...

BTW, is there a schematic diagram? Didn't see one in the github project...

Since static RAM is used, no need for address multiplexing or refresh. That being said, I have looked at the GAL sources and there still is a MUX input which really should not be there. And yes, it does use the ROM relocation trick like the original. There is also a bit of missed opportunity as ...

I used the public source smsq/e version and emulated the aurora registers and set the same vram addresses, I managed to make the smsq/e recognize my card as a gold card with aurora, machine=11. The standard modes worked using the aurora vram space. The higher resolution 512x384 didn't seem to ...

I used the public source smsq/e version and emulated the aurora registers and set the same vram addresses, I managed to make the smsq/e recognize my card as a gold card with aurora, machine=11. The standard modes worked using the aurora vram space. The higher resolution 512x384 didn't seem to work ...

I added 2 new screen resolutions
-512x384 256 colours
-1024x384 16 colours
I tried aurora emulation for smsq/e, it works but doesn't support the higher than 512x256 resolutions, no good so I quit trying.
It currently works with a pretty standard version of gold card smsq/e with the standard ...

I think the target was something like a SGC, like it was for the original Aurora. In that case the bandwidth is far lower, not evenb 2Mbytes/sev as it emulates the original 68008, and needs in theory up to 256k of screen RAM, but these days not nearlčy all Aurora resolutions make sense, so 192k is ...

The first 16550 version with working FIFO came in 1987.

I have tubes of later 16550-compatible ICs. I have never seen a QL driver to support them though - just the older and less useful 6850 that has an incompatible register structure.


The problem with even the original 16450 descendants ...

A reel of 500x RP2350B is 80 cents per piece and is available now. This chip is "5v tolerant*" and has enough GPIO to replace any of the QL chips
...
* 5V tolerant if it is powered up before any signals >4V appear n any GPIO pin.


This should be fairly easy to mitigate with a few protection ...