FPGA replacment for the ZX8301 ULA and more

[Peter]

I got a true dual bus internal video ram that fpga accesses at 16bit words totally independent of the cpu that can simultaneously read and write at it.

So you are using FPGA block RAM for the whole video memory? How large is it?

[lliont]

We wrote simultaneously, I added to my last post.
QL video memory is only 32K so it fits.

[lliont]

I think I solved all the timing issues I'll go with the up-scaled 1024x768 @60hz

So to summarize till now we have

10 Mhz 68008 with no stolen cycles performs at least 2X of the standard QL
2MB of ram
QL-SD interface for 1 SD card with 8 drive images (win1 to win8)
VGA output up-scaled at 1024x768 60Hz
256x256 with 16 colors mode, 8 palettes predefined from 64 colors
512x256 with 4 palettes
60 hardware sprites 15colors + transparency
512k flash that for now only contains the QLSD driver and the toolkit in a plcc socket to be easily reprogrammed, it will also contain the various commands about the sprites and the 16 colors and speed control etc

to be done

one or two extra sound channels (maybe also a variation of ones from my Lion computer)
programmable frequency 64bit counter (I promised I'll include one)
read of the current scan line and anything else I'll think that may be useful
I don't have an idea about the real time clock but can I do something about it or it is a totally separate thing?
maybe a blitter ???
maybe because I have some memory left in the fpga make color tiles for the 512x256 mode

compromises

Although it will be a real QL the following will change

I don't believe most of the expansion cards will work mostly because of the 10Mhz cpu speed, if I had to slow for them any speed advantage would be lost. Maybe again I can add a switch to lower the clock to 7.5Mhz to make them work.
Minerva second screen won't work because of lack of another 32K of free internal fpga memory.

[lliont]

I finished adding one more sound channel, square wave output with pwm volume control.
a 40bit counter with half cycle of variable number of 1/10Mhz steps,
and hardware vertical scrolling of the whole screen with 1 line resolution.


https://drive.google.com/file/d/1TzNN2Z ... sp=sharing

[martyn_hill]

You've excelled yourself (again) Leon!

Whilst I've always liked the idea of Minerva's second screen, I've never actually used it nor played those few games that make use of it...

[lliont]

Well I also found the way to use the 16 colors with basic.
I saw that it can be done in the m68008's demo and searched the ql documentation, it was obscure by I figured it out.
I made the fink command that takes a value from 0 to 15 and sets the ink.
I'll see if this works with the paper also.
I am so pleased with this.

[martyn_hill]

...and so you should be Leon!

Really marvellous - I soooo want one (or four!)

[lliont]

we are getting close

fpaper works as expected

[Chris_68]

Amazing work Leon, well done!!

[Derek_Stewart]

Hi,

This looking great, look forward using one.