ULA replacement basic board

[Peter]

It depends on whether you want to set up a production and sales channel for a wider audience.
If you do, I think you would sell most as 1:1 replacement for the ULA as spare part. Just my personal guess.

Hmmm. Not so sure. As I tend to break my ULAs rarely I'd rather like the enhanced colours. And I don't care so much for exact replication of timing, probably. When there's a picture, there's a picture. When there's a nicer picture, it's nicer

Expert tinkerers like you are exactly the kind of users I did not mean with "wider audience"
The ZX8301 is known as the most vulnerable IC of the QL and there are almost no replacements left.

[Peter]

This design is only the minimal basic design to replace ULA. If I understood it correctly there are other designs in the pipeline with more advanced features. Or at least that’s the way I understand it.

Yeah. That's why I'd leave the basic board as 1:1 replacement, and go for feature & speed improvements with the "high end" board.

[lliont]

No problem I made a version without optimizations but since it's firmware one can choose what he wants.

[lliont]

The optimizations in a system with extra ram for the simple board are tiny and they affect only the accesses at the low memory (that includes screen ram) that the zx8301 performs, the accesses of ram of an expansion card are not affected. I believe it's about 5% faster at low memory accesses.
The board with the 128K static ram has a significant increase of the low memory (and screen) access speed. I believe it's about 30% percent faster.

The simple board with no memory works fine as far as I can test it and a few (maybe 5) boards will be available when parts arrive (may take a month may take longer) for the ones with problem with their zx8301.
No guaranties or responsibility for any damage etc. try it at your own risk, I'm a hobbyist not a company but of course I'll help if needed.

The board with the extra ram also works fine but with standard js rom when ql powers up it won't see the qubide card but after a reset it sees it and works fine, with minerva rom it boots fine from the beginning with out needing a reset. I'll try to figure out why this is happening.

[Peter]

The simple board with no memory works fine as far as I can test it and a few (maybe 5) boards will be available when parts arrive (may take a month may take longer) for the ones with problem with their zx8301.

Many thanks. If there was a well known distribution channel, I think this would sell very well. Please reserve two for me.

[Maskenlos]

Hi Leon,

The simple board with no memory works fine as far as I can test it and a few (maybe 5) boards will be available when parts arrive (may take a month may take longer) for the ones with problem with their zx8301.

Are you going to solder these 5 boards by hand?

Stephan

[lliont]

Hi Stephan

yes, and I'll test them after

[lliont]

I think the original with the qubide ram measures about 1.3 so at 1.586 it's just a little faster but not fast enough to cause problems with games so I'll leave the optimizations on.

Here in the first post I made a mistake and the difference with the optimizations is much smaller than I stated, I remembered wrong figure, it's less than 5%, so there is no point to have 2 versions of firmware for the pcb without ram, I'll keep it close to the original.
But the 128K ram pcb is significantly faster (about 30%) and I hope the small problem with the power on will be solved.

[Derek_Stewart]

Hi,

This is such great enhancement to the QL, I think there will be a demand for more than 5.

I would like one please, I have the the 2 otjwr boards working in a Issue 5 and 6 QL, they also work with QIMSI, Tetroid Trump Card.

Have you thought about getting the SMD components soldered to the PCB by a PCB company, so that all that is required soldering any through hole components and programming the CPLD. This is how I produced the Q68.

While SMD is straight forward, soldering many boards gets a little tedious.

[lliont]

Hi Derek
I think one of the boards you have is the one with the 64K ram that is similar to the 128K board I made now, you must have noticed the faster scrolling on that QL.
Ok till now 2 for Peter and 1 for you.
I'll make more if the first 5 go.