ZX81+35 Clone

[mahjongg]

@ Mahjongg.

As a CPAP user for over 12 years diagnosed with mixed (central and obstructive) sleep apnoea, may I offer the following..

1) persevere with it. After the first night you will want to tear the damn mask off your face and never use it again, please stick with it you will get used to it.

I certainly will, I will however need to get used to it

2) After a time you should find that things like afternoon tiredness disappears and your general well-being should also improve.

3) As you probably may already have been told CPAP is thought to help with the prevention of certain cardio disorders and dementia.

I feel less sleepy in the afternoons already, and yes i have high blood pressure and I hope this will get down

4) Your sleep apnoea will not be cured only treated, especially in the case of central sleep apnoea which is a neurological disorder and to be honest a CPAP machine is useless for central apnea.

In my case it seems to help

5) whereabouts are you from? I only ask because in the UK at least, once your condition starts being treated then your drivers licence should be restored to you.

I'm from the Netherlands, in south-holland near den hague

I wish you the all the best with it.


On a lighter note, the AY unit sounds very promising I look forward to hearing of any progress.

thanks, obviously it will become much harder to get to RevSpace, but with help of a folding bike, (which you can take on a train for free, once folded) I managed to get there last Tuesday.

@ RWAP

Why not fit for car driving?

If from a fitness point of view then ok I get it, but legally once diagnosed and under treatment the DVLA should issue you a letter saying your licence is restored and you're ok to drive.

I was told that if the treatment helped for a period of three months to get my apneas below 15 an hour, I could get back my license to drive again. I have not been presented with an official paper that said my driving license was revoked, just my doctor telling me so.

[Moggy]

'@Majohngg.


Quote.

"I was told that if the treatment helped for a period of three months to get my apneas below 15 an hour, I could get back my license to drive again. I have not been presented with an official paper that said my driving license was revoked, just my doctor telling me so".



In the UK once treatment begins as certified by the consultant (senior doctor) then your licence is normally restored to you.

How it works in the UK is that once diagnosed you inform the licence authorities who then suspend your licence. then once treatment begins your doctor informs them treatment has begun and providing there are no other medical issues your licence is restored there is no need of going below so many episodes an hour, besides how would they measure it?

I would advise that you contact your local driving authority fto make it clear and not just take your doctors word for it.


All the best for the future.


Regards.

Moggy.

[mahjongg]

Started with PSG sound expansion board.
Preliminary schematic can be found here: https://revspace.nl/ZX81%2B34_ZX81_clon ... sion_board.

[mahjongg]

The first schematic of the PSG expansion board for my ZX81+35 is ready, only the GPIO's are not yet used, they will be used to interface to an SD-Card slot, to that end register reading is already implemented.
Sound output to a stereo jack is implemented.
This version is ZON X-81 compatible, it ignores A4, I don't expect it will be used with a Spectrum .

PSG for ZX81+35 REV 1.2 1000px.png (124.01 KiB) Viewed 4600 times

[mahjongg]

Second (final) version with SD-Card slot interface connected to the GPIO's
notice one error, the DAT0/DO (data read) line should have a larger series resistor (R9) than 33E so that a GPIO output wont damage the sd-card output port, also the pull-up resistor should be adjusted accordingly, I suggest R9 is 1K and pull-up = 10K. Its possible that the pull-up should go to 5V instead of 3V3.

PSG for ZX81+35 REV 1.3.png

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More info as always on revspace.

[mahjongg]

Here a corrected schematic, with 5V to 3V3 resistor dividers so the SD-card doesn't get 5V signals, but normal 3V3 levels. For signals travelling from the SD-card to the PSG, the resistor divider essentially does nothing,and the PSG can handle 3V3 levels ( anything above 2V4 will work) . clock/latch inputs are held low when the PSG doesn't drive them, and data line (DI and DO) are pulled high.

PSG for ZX81+35 REV 1.4.png

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resistor values were changed, the 2K2 become 100K, the 22K become 10K, and the 33K become 15K, so the SD card data lines can reliably pull the GPIO pin(s) low.

Received a request to consider adding support for two PSG's for 6-channel sound, using a second board.
Considering adding a fifth AND input for the A0, A1, A2, and A3 AND, to which you can have a choice of either high, or one of the address lines in the range A4 to A6. so you can use up to three PSG boards in "tandem".

[mahjongg]

So here its is, a redesign adding multiple PSG board support, and also support for use with other boards that use address lines as (active low) "chip selects" on A4, A5 or A6.

PSG for ZX81+35 REV 1.5.png

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Note; I also implemented a "audio interconnect" header to mix sound from the second board with the first board.

To use two boards, assign one to an active low address line which is blocked on the other board, and vice versa.

[mahjongg]

this project was delayed when I found out a mistake in my original ZX81+35 design, in that the edge connector was mirrored when I transposed the edge connector from the top of the PCB to the left side I made a mistake, and pin 1 should be on the bottom (toward the keyboard) but its at the top,

So I just had to re-design the layout of my ZX81+35 clone.

That job is now finished (minus automatic route checking and optimizing).

I will return to the PSG adapter design soon.

[mahjongg]

ZX81+35 revision 4.0 layout is finished.
Still have to solve the image stability when running in turbo mode, (another issue, AFAIK the only one remaining) but I have some ideas for a fix.
Also, I will now return to work on the PSG board, with a correct edge connector orientation.

This is the new layout:

Layout_ZX81+35_Rev4.0_20_September_2016.png

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