ULA1 nextgen idea...

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Nasta
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Re: ULA1 nextgen idea...

Postby Nasta » Mon Sep 13, 2021 10:20 am

OK, this needs to step back a few steps - are we talking about an ULA1 pin-to-pin replacement or a new chip or board that goes into new hardware (new motherboard etc...)? Asking because a good definition is needed or the thread title might be misleading. If it is a compatible replacement, a refresher on how it connects into the rest of the motherboard circuit may be in order, the QL iss6 schematic with all corrections can be found here:
http://dilwyn.qlforum.co.uk/docs/hardware/QLissue6.pdf


Derek_Stewart
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Re: ULA1 nextgen idea...

Postby Derek_Stewart » Mon Sep 13, 2021 11:25 am

Hi,

Can you define what ULA1 and ULA2 is?


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Nasta
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Re: ULA1 nextgen idea...

Postby Nasta » Mon Sep 13, 2021 12:32 pm

ULA1 = ZX8301 ULA chip (Video and RAM control)
ULA2 = ZX8302 ULA chip (I/O, RTC, IPC comms)


Derek_Stewart
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Re: ULA1 nextgen idea...

Postby Derek_Stewart » Mon Sep 13, 2021 12:48 pm

Hi

Thank uou for the clarification.

I always wondered if ULA1 could be replaced with a new ULA with faster ram, this would only be used for Video Ram.

The idea was to eliminate the ram contension on the QL Board.


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Derek
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Re: ULA1 nextgen idea...

Postby Derek_Stewart » Tue Sep 14, 2021 9:24 am

This all sounds what I meant...

But you said it is not a QL anymore...

I have PCs, Amigas, Atari STs, Spectrums, ZX81s and many more...

The QL is the operating system, not the hardware it runs on.

If you impose the limitations of a the sole of the QL is a 128K with expansion to 640K, twin 100K MIcrodrives, QL Network, then nothing moves on.

I can write the same programme in Superbasic, Assembler, on a QL with 128K ram bulit in 1984 and run the same programme on a Q68 that was built in 2020.


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Derek
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Re: ULA1 nextgen idea...

Postby Pr0f » Tue Sep 14, 2021 12:52 pm

I believe that is what is known as an illustration - that the same program could be written on original hardware - new hardware platform and probably on the myriad of emulators out there - it was an illustration of what a QL is from a software layer perspective.

With regards to the topic itself - we started off talking about a possible enhanced but potentially plug in replacement for the ZX8301 - then it went off into I don't know what...

With this particular chip being prone to damage from plugging / unplugging monitors on the fly, and also from the fact that monitors that support the old broadcast scan rate with the QL's perverse timings for front and back porch, etc - it would be good to see if a plugin replacement - possibly offering more video modes, could be made that would drive VGA/HDMI directly, not be prone to damage when lived plugged could be developed.


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Re: ULA1 nextgen idea...

Postby Derek_Stewart » Tue Sep 14, 2021 2:23 pm

Hi,

My apologies for distrcting the thresd awy from the original topic.

Let me know when you have a working proto-type.

....now back sleep.


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Derek
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Re: ULA1 nextgen idea...

Postby Pr0f » Tue Sep 14, 2021 3:27 pm

Brane2 wrote:
WRT HDMI, I remmber seeing some serializer for it (NXP?), but can't find it now...



Seen a couple of these - black something rings a bell - I have details at home - I will post it when I get back - was based on a lattice FPGA I believe...


Nasta
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Re: ULA1 nextgen idea...

Postby Nasta » Wed Sep 15, 2021 1:42 pm

The original pinout of the 8301 limits things quite a lot, it would be interesting to define some ground rules of the project with this in mind... and then the general context, scope and limitations.



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