ZXblast - ZX81 memory extension plus USB

[blittled]

Did I miss a chance to get a ZXblast or is it still being developed?

[PokeMon]

Still under development, checkout here in about two weeks.

[PokeMon]

So it took some longer time to get the ZXblast work as it should. In the meantime loading and saving programs/data is implemented and working now and still missing a configuration utility for the ZXblast and a file manager. In the existing USB driver it is only loading and saving implemented but no subdirectory support and no directory listings. I will transfer this tool to the ZXmore later, too, when released for the ZXblast so you could expect an update here soon.

The big time delay is due to unexpected problems due to different hardware solutions inside ZXmore and a standard ZX81 (video logic). In the ZXmore the NMIs are catched at the last NMI and all register are stored before a task can change. This is not possible within the short sync time of the last (additional) sync NMI, even not with double frequency (6.5 MHz). This way I introduced a longer sync phase, taking two NMI while the line counter is activated later via a r/c timing combination.

I can not influence the video logic in a standard ZX81 in this way and can not use long NMIs cause they are generated internally. The technique to control is quite different and catches the very first NMI instead. So timing requirements are not that hard and would be much better than catching the penultimate NMI which would be different on PAL and NTSC (55 vs. 31 lines) and checking AF' counter is time-consuming as well and I like to spare the system resources (remaining cpu time). This required the development of a complete different hardware logic as well as completely new drivers and adapting the load/save routines for this. But fortunately solved now.

So how is it going on now ? I will work on the config tool and a convenient file manager with subdirectory support and will probably publish the first release around end of next week and then the ZXblast can be sold. So I will come back soon on this.

[mrtinb]

[andrewmunro]

Great News. Looking forward to the release.

[mrtinb]

This is the cool stuff we've been waiting for all summer.

[PokeMon]

I have still some issues when loading some files - for example HRG driver and after the driver a program using this driver (sinus.p for example) and one program refuses to be loaded/executed at all. So I am in a debug session and hope to find the problem soon.

[mrtinb]

Is it successfully moving forward? Are bugs being crushed?

[gammaray]

No rush though...

Is it successfully moving forward? Are bugs being crushed?

[PokeMon]

I am still on it while available free time was going down through heavy work load in my job.
I hope to release the first version very soon but want to have it quite stable in interest of the paying users.
The more testing the more you find some tricky timing bugs/crashes which occur sometimes and not easy to find.
But I am still working on it.