a DIY home build project...

The Thor, Aurora, Q40 and Q60 etc. are discussed here.
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Pr0f
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Re: a DIY home build project...

Postby Pr0f » Thu Jan 11, 2018 11:34 am

I am using a 68901, which could and probably will.eventually go in the fpga with video, the reason for using the separate chip to start with is ease of testing. This acts as interrupt controller for the QL, totally replacing the zx8302. It has a serial controller on board, 4 timers, and 8 programmable interrupt lines. It's this device that talks with the propeller over a much faster serial interface, moving 8 bits not 4 bits as in the zx8302. Extint can be programmed for level or either edge, and all interrupt sources are maskable. The usb fifo full and empty also use 2 of the lines. So I needed something that would work with existing zx8302 and the 68901, hence the propeller.


Oh, and the DUART is the 2nd generation Philips upgrade of the Motorola DUART, giving baud rates up to 230K, independant for both tx and rx on both channels, plus programmable stop and parity, fifos are 8 bytes, but are closely linked to hanshaking, unlike the 16550. Its a tried and tested chip :-) also perfect for 68k bus.


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Re: a DIY home build project...

Postby Dave » Thu Jan 11, 2018 4:36 pm

I'm particularly interested in the DUART - which one is it, and have you a functional driver or schematic for it yet? I need a faster serial on the QL for this internet card, which works through serial and 9,600 doesn't cut it.


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Pr0f
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Re: a DIY home build project...

Postby Pr0f » Thu Jan 11, 2018 9:04 pm

This is the one:

https://www.google.co.uk/url?sa=t&rct=j ... 8D-llqEBoh

It has some distinct advantage over the 68681 part it is descended from. Deeper FIFO's but also more choices of baud rates and higher rates all from the same 3.6MHz crystal. Another advantage is this chip doesn't suffer the restriction the earlier models had on bus clock cycle limits, which means it will happily interface to faster processors.


Dave
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Re: a DIY home build project...

Postby Dave » Fri Jan 12, 2018 5:11 am

I'll email you about this.


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Peter
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Re: a DIY home build project...

Postby Peter » Mon Jan 15, 2018 1:02 pm

Dave wrote:The serial communication 8049 -> 8302 is a real bottleneck.

Not, if SER is implemented separately anyway, and all you want is the matrix keyboard.

Dave wrote:Propeller or FPGA? Not the most important question. Certainly shouldn't be a show stopper that prevents people developing and moving forward...

My point was overall development time, on the basis that the design will later include an FPGA anyway. If mainly the first step is in view, and Pr0f is very familiar with that Microcontroller, it makes sense to just use it and move forward.

In some way (except the CPU debugging) the Q68 was easier to design than this, because more wiring was done inside a chip, less on PCB. And I know how long the Q68 took...


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Re: a DIY home build project...

Postby tofro » Mon Jan 15, 2018 1:20 pm

Peter wrote:
Dave wrote:The serial communication 8049 -> 8302 is a real bottleneck.

Not, if SER is implemented separately anyway, and all you want is the matrix keyboard.


That is still somewhat a state-of-the art concept - modern PS/2 and USB keyboards still do it more or less the same way.

What is a bottleneck is the serial ports and sound, which is clearly a nuisance on the QL - Even the Spectrum's main-CPU-driven sound is nicer to program. Some of the stuff the Spectrum guys do with their single bit is really amazing and beyond all capability of the QL's 8049 (current favourite: http://converter.dev.artweb.ee/music/50 ... 6_secs.mp3 ).

Tobias


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Pr0f
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Re: a DIY home build project...

Postby Pr0f » Mon Jan 15, 2018 1:59 pm

There is code available for download to the propeller that emulates ay8910, Commodore SID chip and a WAV player, so more interesting sound options are there, a driver would be required to push the data down to the propeller, but using an 8 bit fast serial link running at 1M, you can shift a lot of data. Emulation of the QL sound was just a requirement for compatibility with Basic.

Not quite sure what you meant by 'state of the art concept' - you'd have to explain that.


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Peter
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Re: a DIY home build project...

Postby Peter » Mon Jan 15, 2018 2:10 pm

tofro wrote:What is a bottleneck is the serial ports and sound, which is clearly a nuisance on the QL - Even the Spectrum's main-CPU-driven sound is nicer to program. Some of the stuff the Spectrum guys do with their single bit is really amazing and beyond all capability of the QL's 8049

Totally agreed. That's (among other things like not using 16 colours) why I do not find the QL a clever hardware design, compared to Sinclair standards of that time. IMO the 8049 has complicated, enlarged, price-increased and delayed the design with no practical gain.



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