CPLD replacement for ZX8301

[Derek_Stewart]

Hi,

Maybe more video ram could be added so that new screen modes would have dedicated ram, leaving the normal 128K ram uncontended.

But I am not sure how the operating system would handle this.

[lliont]

I am just thinking if a QL fellow is seeking for an ULA replacement and come across this discussion. May be you could consider to make a zip file, a bundle with the information to build a ULA replacement without any additional functionality. Just a 1:1 replacement with the original ULA. This may contain the Gerber, The CLD code, schematics and just 2-3 links where to get the oscillator and the CPLD and maybe 1-2 picture. Means one of the early but stable version you had on your project page but is gone due to further development. And then share in this Thread

Hi Stephan
The version I have published at hackaday.io can be used as just a 1:1 replacement, it has extra features but if one doesn't enable them it's just a replacement of the original. Also if one doesn't want the 16 color composite output then he can leave out the AD724, the crystal, the variable capacitor and all the resistors and still have a working standard ULA. At hackaday I have published everything needed to build the ula clone, the two new SBasic commands binary, a schematic and some instructions (link to my projects at my signature).

About the other suggestions, the CPLDs I have used (that I am able to solder and test) have reached their limits, I'll see what more can be done with them and maybe with more powerful ic's in the future (with a fpga I can do all and more but then it's a new project and much more expensive one).

[Peter]

Looks like all this project needs now is Aurora mode implemented to have an Aurora workalike in combination with an SGC

The Autora screen area is at $4C0000. So in this ULA-socket project, the Aurora modes can not be implemented.

[Peter]

At hackaday I have published everything needed to build the ula clone, the two new SBasic commands binary, a schematic and some instructions (link to my projects at my signature).

You have done an impressive job! And it is fully up to you how well you wish to support reproduction by others. I know how much work that can be.

But looking at the schematics and the depicted PCBs, they do not go together. For example, one IC in the schematics does not even appear on the PCB picture. Building your interface is not hindered by the amount of information you are willing to share. But inconsistencies caused by changes make things a bit confusing. If you could "freeze" one version where pictures, schematics, partslist and Gerbers fit exactly, less guesswork would be needed. Actually, I think you had already been there in the past.

And if you are interested in some feedback: As matter of personal taste, I would prefer a shrinked version which just replaces the original ULA. I was even considering making my own PCB for that reason. Didn't do that, as the logic is (understandbly) closed source and I'd prefer a smaller sized chip. Which is probably better as I have too many projects anyway.

[Peter]

About the other suggestions, the CPLDs I have used (that I am able to solder and test) have reached their limits, I'll see what more can be done with them and maybe with more powerful ic's in the future (with a fpga I can do all and more but then it's a new project and much more expensive one).

I see that the required 5V tolerance adds some resistor arrays, and some LDO regulators are needed. Which increases complexity but has little impact on costs. A 10 € ECP5 FPGA even includes your 64 KB RAM on chip. The current SRAM and obsolete PLD seem to cost no less.

[lliont]

I maybe forgot to update the schematic, I'll do that asap.
I'm thinking of a pcb with both cpu and ula sockets so I can then add 1MB ram totally controlled by the ula and then even more speed and other features will be possible.

[lliont]

I see that the required 5V tolerance adds some resistor arrays, and some LDO regulators are needed. Which increases complexity but has little impact on costs. A 10 € ECP5 FPGA even includes your 64 KB RAM on chip. The current SRAM and obsolete PLD seem to cost no less.

Yes but can I solder it ?
I see it comes at CSFBGA-285 package !
What programming software (is it free?) and adapter I'll need.
I already made a pcb with the not obsolete Xilinx cpld and I am waiting for parts to test it.

[lliont]

For example, one IC in the schematics does not even appear on the PCB picture.

No the schematic is ok, which IC doesn't appear ?
You confused the ULA socket with an IC ? Or you look the picture at the project logs that is the history of the project.
I'll add a new log entry so not to be confusing.
The version at hackaday.io is consistent and unchanged for 2 months now (I only updated the firmware 17th of February to fix a small bug).
I'll find a previous more compact version I had made and make it available again.

I'm still a Bent Pin Expansion Port

[Maskenlos]

I'll find a previous more compact version I had made and make it available again.

Thanks a lot Leon in advance. I really think this would be of great interest for not so H/W experienced users.

[Peter]

I see that the required 5V tolerance adds some resistor arrays, and some LDO regulators are needed. Which increases complexity but has little impact on costs. A 10 € ECP5 FPGA even includes your 64 KB RAM on chip. The current SRAM and obsolete PLD seem to cost no less.

Yes but can I solder it ?
I see it comes at CSFBGA-285 package !

I'm using the caBGA-256 package (14 x 14 mm). Personally, I have less problems soldering that manually than TQFP.
There is also a new TQFP-144 package.

What programming software (is it free?) and adapter I'll need.

Lattice Diamond, free, HW-USBN-2A for € 20 at eBay.