QL upgrade versus Q68

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Peter
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Re: QL upgrade versus Q68

Postby Peter » Tue Mar 14, 2017 2:01 pm

Yes, it is certainly a good idea to have the digital video signals avaiable. I missed this a lot on the Q60, when CRT Multisync became rare. When I designed the Q68 prototype, I used a 2.54 mm grid for the DAC resistors, giving the option of using the pins for a connector.

Unfortunately, when I moved on to the SMD oriented series production version, I forgot about this. I also made the unlucky decision to exchange the 1.2V votage generator for a cheaper/smaller one, which has now become minimum order quantity 3000. And I forgot an extra capacitor for the power supply at the FPGA Bank responsible for sound output. However, every PCB redesign bears some risk of making a new mistake, so I decided to leave the successfully tested layout untouched for series production.

I doubt that it is already a good idea to abandon VGA in favour for HDMI on the Q68. This is retro computing, so many will prefer traditional 4:3 screen format. This increases the likelyhood that an older monitor is used. I even fear that the Q68 will still be used with CRT somewhere. Who knows? Personally I use both a 4:3 flatscreen and a Full HD flatscreen, but I prefer the 4:3 format.

I try to steer a middle course by letting the Q68 produce a stritcly VESA compliant 1024x768 @ 60 Hz VGA signal in all video modes. Even the dumbest VGA-HDMI converter should recognize this most widely used VGA format.

I succesfully tried a cheap VGA-HDMI converter, so a batch of these could be bought to be on the safe side. The box of the converter can be removed, so a tinkerer could mount its small PCB inside the case I have suggested for the Q68. I found such a converter a better solution than using a Raspberry PI for HDMI like the ZX Spectrum Next.

By the way, will that wonderful ZX Spectrum Next case from Rick Dickinson ever be produced in series?


Nasta
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Re: QL upgrade versus Q68

Postby Nasta » Tue Mar 14, 2017 2:44 pm

VESA compatibility was really my first worry. There is really no shortage of monitors with VGA input (yet :) ) but monitors as such are getting dumber by the model. Already a few years ago when I was designing some gaming hardware (for casinos), we had big problems with monitors that would not correctly synch to even standard video signals, speciffically in the case where the base resolution was indeed VESA but not the full resolution was used (for instance the base resolution is 1024x768 but only 1024x640 is used). Funnily older monitors would work great and were flexible enough to adjust whatever you wanted, while newer ones had some really odd ideas like they would not auto-adjust, and then you could manually adjust ALMOST properly, at which point you could do another auto-adjust, after which you could get it manually even closer to perfect, etc ... after about 4-5 iterations it would work.

Digital video does however have one other appeal, especially given how small Q68 is - these days it's no big deal finding raw LCD panels at reasonable prices, with (mostly) wide screen resolutions like 1024x640, which are actually closer to the original QL spec. These panels use a direct digital interface, and look very enticing from the point of making a nice portable unit based on Q68.

BTW I like the PCB a lot, is it a 2-layer design?


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dilwyn
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Re: QL upgrade versus Q68

Postby dilwyn » Tue Mar 14, 2017 4:20 pm

Nasta wrote:Digital video does however have one other appeal, especially given how small Q68 is - these days it's no big deal finding raw LCD panels at reasonable prices, with (mostly) wide screen resolutions like 1024x640, which are actually closer to the original QL spec. These panels use a direct digital interface, and look very enticing from the point of making a nice portable unit based on Q68.

Now that is a FANTASTIC idea.


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vanpeebles
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Re: QL upgrade versus Q68

Postby vanpeebles » Wed Mar 15, 2017 11:16 am

:o QL Laptop!


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Peter
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Re: QL upgrade versus Q68

Postby Peter » Wed Mar 15, 2017 1:36 pm

Nasta wrote:VESA compatibility was really my first worry. There is really no shortage of monitors with VGA input (yet :) ) but monitors as such are getting dumber by the model.


I could not agree more. Still I hope that 1024x768 @ 60 Hz with perfectly VESA compliant front & back porch timings for the syncs will satisfy the widest possible range of devices.
At least I could not think of any other format that would seem more suitable.

Nasta wrote:Digital video does however have one other appeal, especially given how small Q68 is


... and I didn't even optimize for size. Q68 has widely spaced, single sided component placement and classic, large THT connectors. ;)

Q68 is an attempt for Sinclair-style simplicity. The relatively small size was just a side-effect.

Nasta wrote: these days it's no big deal finding raw LCD panels at reasonable prices, with (mostly) wide screen resolutions like 1024x640, which are actually closer to the original QL spec. These panels use a direct digital interface, and look very enticing from the point of making a nice portable unit based on Q68.


I do agree. But as mentioned, I forgot the (previously existing) digital connectivity option, when I redesigned the PCB toward machine manufature.

Today, we must compare time, risk and cost of one more PCB prototyping (and manual finepitch SMD soldering!) iteration to having this feauture.

Nasta wrote:BTW I like the PCB a lot, is it a 2-layer design?


Thanks, you should see the Q68 in real :) From an aesthetical viewpoint, the Q68 is probably the best PCB I ever designed. Yes it's a two layer PCB, still the groundplane covers almost the complete bottom. There are also a lot of other details that a user will not notice, but you as an electronics expert surely will. ;)

By the way, do you have some time you would like to spend with the Q68 prior to public release? Then contact me privately please.


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Peter
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Re: QL upgrade versus Q68

Postby Peter » Thu Mar 16, 2017 12:01 pm

Peter wrote:
Nasta wrote:VESA compatibility was really my first worry. There is really no shortage of monitors with VGA input (yet :) ) but monitors as such are getting dumber by the model.


I could not agree more. Still I hope that 1024x768 @ 60 Hz with perfectly VESA compliant front & back porch timings for the syncs will satisfy the widest possible range of devices.
At least I could not think of any other format that would seem more suitable.

Nasta wrote:Digital video does however have one other appeal, especially given how small Q68 is


... and I didn't even optimize for size. Q68 has widely spaced, single sided component placement and classic, large THT connectors. ;)

Q68 is an attempt for Sinclair-style simplicity. The relatively small size was just a side-effect.

Nasta wrote: these days it's no big deal finding raw LCD panels at reasonable prices, with (mostly) wide screen resolutions like 1024x640, which are actually closer to the original QL spec. These panels use a direct digital interface, and look very enticing from the point of making a nice portable unit based on Q68.


I do agree. But as mentioned, I forgot the (previously existing) digital connectivity option, when I redesigned the PCB toward machine manufature.

Today, we must compare time, risk and cost of one more PCB prototyping (and manual finepitch SMD soldering!) iteration to having this feauture.

Nasta wrote:BTW I like the PCB a lot, is it a 2-layer design?


Thanks, you should see the Q68 in real :) From an aesthetical viewpoint, the Q68 is probably the best PCB I ever designed. Yes it's a two layer PCB, still the groundplane covers almost the complete bottom. There are also other details that an average user will not notice, but you as an electronics expert surely will. ;)

By the way, do you have some time you would like to spend with the Q68 prior to public release? Then contact me privately please.


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Re: QL upgrade versus Q68

Postby Doug » Thu Apr 06, 2017 2:27 pm

Love the idea of a expansion version, even if the QL doesn't end up doing much itself, it would be cool for it to be working in amongst the old hardware :)


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Peter
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Re: QL upgrade versus Q68

Postby Peter » Fri Apr 07, 2017 9:27 am

Thank you Doug. Meanwhile "alea iacta est" for the Q68 as a standalone system. As the Q68 fits into a QL case mechanically, it is still possible to

a) Connect the Q68 to the QL mainboard with a simple adaptor (yet to be designed) and let the 68008 work as coprocessor to exchange some QL aspects like keyboard or network with the Q68.

b) Remove the QL mainboard and design a more comprehensive Q68 daughter board with connectors for keyboard, LEDs, etc.

Both solutions require a little software and hardware development. It remains to be seen if someone finds the motivation for that, or if people rather stick to traditional QL expansions.


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Peter
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Re: QL upgrade versus Q68

Postby Peter » Tue Oct 10, 2017 10:18 am

tofro wrote:That's what I'm saying, Peter:

QL keyboard matrix to PS/2 shouldn't be too difficult to implement for the average µC tinkerer.

Tobias


XorA wrote:Just needs a i2c GPIO expander chip and a native driver. No uC required at all!

G


Do you have a recommendation for a suitable chip?

Peter


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Re: QL upgrade versus Q68

Postby XorA » Tue Oct 10, 2017 10:50 am

Peter wrote:
tofro wrote:That's what I'm saying, Peter:

QL keyboard matrix to PS/2 shouldn't be too difficult to implement for the average µC tinkerer.

Tobias


XorA wrote:Just needs a i2c GPIO expander chip and a native driver. No uC required at all!

G


Do you have a recommendation for a suitable chip?

Peter


Unfortunately not, maybe Dave could recommend something current (Ive been doing ARM server stuff for last 5 years).



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