Issue Tx boards discussions

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Derek_Stewart
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Re: Issue Tx boards discussions

Postby Derek_Stewart » Fri Nov 29, 2019 8:57 pm

Chr$ wrote:That's incredible!

So let me get this straight... this is basically intended as a replacement motherboard product? It will technically be about the same spec-wise as the original (but with proper D-SUB added, better video out and more convenient power requirements) but you'll still need to use your original custom chips like the ZX8301 and ZX8302 (because those aren't available new)?

Could the 8302 and 8301 be replaced by a FPGA or CPLD?

This could allow the core of each chip to updated.


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Derek
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Re: Issue Tx boards discussions

Postby stephen_usher » Fri Nov 29, 2019 11:03 pm

Derek_Stewart wrote:
Chr$ wrote:That's incredible!

So let me get this straight... this is basically intended as a replacement motherboard product? It will technically be about the same spec-wise as the original (but with proper D-SUB added, better video out and more convenient power requirements) but you'll still need to use your original custom chips like the ZX8301 and ZX8302 (because those aren't available new)?

Could the 8302 and 8301 be replaced by a FPGA or CPLD?

This could allow the core of each chip to updated.


But then you're starting to build a whole new machine, surely? If you're remaking the ZX8301 and ZX8302 why not widen the bus to the full 16 bits and use a full 68000?... etc. The rabbit hole becomes deep quite quickly.


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Peter
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Re: Issue Tx boards discussions

Postby Peter » Fri Nov 29, 2019 11:05 pm

Derek_Stewart wrote:Could the 8302 and 8301 be replaced by a FPGA or CPLD?

Yes, but not directly as a chip in DIL case. You'd need a chip in a totally different case, voltage regulator(s), and in case of an FPGA, voltage level conversion for the inputs. This could be placed on a PCB which plugs into a ZX8301 / ZX8302 socket.

But for my taste, that would affect the retro appeal of this board.


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Re: Issue Tx boards discussions

Postby swensont » Sat Nov 30, 2019 4:16 am

On the US QL, both serial 1 and serial 2 were male connectors. Serial 1 was DTE and serial 2 was DCE. All this means is that pins 2 and 3 were swapped. For compatibility reasons, I think this should be the same on any new boards. If someone needs serial 2 to be DTE, a simple serial jumper adapter can be made with a female DB-9, male DB-9, two bolts, a number of nuts and some short bits of wire (I've done this to adapt serial 1 to a serial mouse).

Tim


Derek_Stewart
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Re: Issue Tx boards discussions

Postby Derek_Stewart » Sat Nov 30, 2019 8:44 pm

Peter wrote:
Derek_Stewart wrote:Could the 8302 and 8301 be replaced by a FPGA or CPLD?

Yes, but not directly as a chip in DIL case. You'd need a chip in a totally different case, voltage regulator(s), and in case of an FPGA, voltage level conversion for the inputs. This could be placed on a PCB which plugs into a ZX8301 / ZX8302 socket.

But for my taste, that would affect the retro appeal of this board.

Not quite what I meant, what if the 8301 or 8302 chip become unavailable, there would no replacement parts.

I have seen the Spectrum and ZX81 ULAs reproduced into a modern part.

The 8049 can be replaced by a Hermes chip, just the 8301 and 8302 with no alternatives.

Could this be done with the QL custom chips?


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Derek
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Re: Issue Tx boards discussions

Postby stephen_usher » Sat Nov 30, 2019 11:03 pm

Maybe if you asked Charles Ingley (@Bloodnok) nicely he could look into it?

Of course, someone would have to give him a complete functional spec. for each device.


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QLvsJAGUAR
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Re: Issue Tx boards discussions

Postby QLvsJAGUAR » Sun Dec 01, 2019 4:28 pm

First, keep the great work going, Vitaliy!

From my opinion the Tx issues are much more that just retro QL, while the 1983-1986 THORN EMI Datatech Dxx issues and the SAMSUNG USx(.y) issues both share some bad Sinclair design and feature decisions. Looking at the Tx issues as 2019/2020 state of the art QL, I see the need that:
tetroid wrote:1. SER and CTL M/F types and pinouts

Both SER ports should have male DE-9 with pin assignments 1:1 to common PC standard, so that one can buy/get a PC RS232 device (mouse, printer, null-modem-cable, etc) and use it without hassle (as long as baud rate matches).
Both CTL ports should be "ATARI" compatible for both Joysticks and Mice (the SAMSUNG USx(.y) issues were ok for Joysticks but did not have the power for Mice).

tetroid wrote:3.Discussions about more significant changes for the next versions ( not for T2 ).
Possible we need to remove the internal microdrives?
In any case we can use external microdrives and v-Drive QL.

Possible we need to remove the NET connectors or change it to sound connector ? I see the attempts to use the AY3-89x chip on QL.

Please keep the internal Microdrives.

Please also keep QL NET. It is very useful to connect QLs together and also share data with QXL-PCs and CST Thors.

Regarding the AY3-89x, nice would be an on Tx board implementation of a let's say AY-3-8910A similar and compatible to the QSOUND expansion card. See thread viewtopic.php?f=2&t=1587
Regarding the firmware, a later version 1.31 can be found in the Toolkits section of the SBASIC/SuperBASIC Reference Manual (e.g. in THE DISTRIBUTION in the folder/file \doc\basic\SBASIC_SuperBASIC_Reference_Manual\Toolkits\QSOUND_V1_31).

QL forever!


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thorsinclair
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Re: Issue Tx boards discussions

Postby thorsinclair » Mon Dec 02, 2019 8:11 am

In order to reply to open questions regarding the Tx could there be taken in consideration the issue 8 project of Nasta and Dave? Or only to get some inspirations?

By the way I like the naming ... T1, T2 ... reminds "The Terminator" :D :evil:


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Peter
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Re: Issue Tx boards discussions

Postby Peter » Mon Dec 02, 2019 3:50 pm

QLvsJAGUAR wrote:Both SER ports should have male DE-9 with pin assignments 1:1 to common PC standard, so that one can buy/get a PC RS232 device (mouse, printer, null-modem-cable, etc) and use it without hassle (as long as baud rate matches).

That would also make it fully compatible to Q40, Q60 and Q68. Still I'm reluctant to recommend the PC pinout - I understand the Tx as a strict retro board, so it makes some sense to keep original QL equipment like printers, printer interfaces or QL-taylormade serial cables directly usable.

QLvsJAGUAR wrote:Please keep the internal Microdrives.

Yes please. It's essential for a board like this.

QLvsJAGUAR wrote:Please also keep QL NET. It is very useful to connect QLs together and also share data with QXL-PCs and CST Thors.

Yes please. Not to forget the Q68 - which probably has more active users than QXL and Thor these days.

QLvsJAGUAR wrote:Regarding the AY3-89x, nice would be an on Tx board implementation of a let's say AY-3-8910A similar and compatible to the QSOUND expansion card.

I differ here - to only integrate new sound seems a totally arbitrary choice. Others might prefer QIMI (or other mouse port) integration, others memory expansion integration, others better video, etc. If a relatively rare card like Qsound is added, then where does the choice of features start, and where does it end?

For my taste, this board should remain close to the QL, a replacement with moderate improvements for quality and manufacturablity, but no feature creep. I'm not against a new mainboard that massively upgrades the QL - but that would be a totally different project in my opinion.


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Cristian
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Re: Issue Tx boards discussions

Postby Cristian » Mon Dec 02, 2019 7:16 pm

thorsinclair wrote:By the way I like the naming ... T1, T2 ... reminds "The Terminator" :D :evil:

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