ZX81 Clone Tynemouth Minstrel 3

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
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1024MAK
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by 1024MAK »

See this thread.

Mark
Mustermann
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by Mustermann »

tynemouthsoftware wrote: Mon Jan 20, 2020 12:22 pm Looks interesting. A couple of questions. What extra software can you now run with the 56K RAM that couldn't run before, and are there any programs which did run with 16/32K but will not work with the extra RAM? I have not found much software which needs more that the standard 16K, so trying to judge if it is worth adding this to a future Minstrel.

Also, what is the test program you are using, my googling ability has failed me?

Thanks,

Dave
I used sysinfo.p as test program. The program can be found here:
http://www.8bit-wiki.de/8bitdb.html?&no ... b4c83c75c1

Extra things that will work with 56k:

POKE 16389,255
NEW
DIM A(9000)

Will not work without additional RAM(tested).

I found that "The Crystal Frog" need RAM between 16k and 48k(tested)

This can be fixed by changing RAM configuration from 8k-40k to 16k-48k but there are other programs that need 8k-16k.

If I am right, hero.81 need 48k RAM and beamride.81 need 32k between 16k and 48k(not tested yet).

Ok. these are only a very few programs, but I am also planning to build a ROM overlay to run alternative ROMs.

For the ROM overlay I need to solve at least one additional issue:

RAM is connected to CPU in refresh cycle, not to character generator as ROM is.
If I will write an ROM image to RAM and then swith 0k-8k to RAM, Characters can't be read from RAM.

Have a nice weekend,

Max
ZX81 issue 1 near to original state
ZX81 issue 1 56k internal ram with battery backup, UDG, CHR$128 and WRX enabled
Minstrel 3 ZX81 clone 64k with battery backup, UDG, CHR$128 and WRX enabled
Mustermann
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by Mustermann »

Hero(hero.p) tested as working with Minstrel 3 + 56k.

I had some issues with my TFT monitor running Minstrel in PAL mode when Hero was loaded.
This could be solved by switching to NTSC mode(even if I am in Europe).

Max
Attachments
Hero.jpg
ZX81 issue 1 near to original state
ZX81 issue 1 56k internal ram with battery backup, UDG, CHR$128 and WRX enabled
Minstrel 3 ZX81 clone 64k with battery backup, UDG, CHR$128 and WRX enabled
willinliv
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by willinliv »

Mustermann wrote: Sun Dec 29, 2019 3:26 pm
So an amplifier is needed that is able to give at least 8Vpp. An audio amplifier based on TDA2002 did it when VCC is at least 12V.
Just to say that this was a big help in getting programmes to load on my Minstrel 3 - the kit on eBay was actually for a TDA2030A, approx £3. This may be an alternative to the Arduino boards talked about elsewhere. With this I was able to get a programme loaded from .wav on playing on my Edirol MP3 player at 100% volume with a supply of approx 7V to the amplifier(where it would not load previously). Obviously I first connected everything to the Mic jack :roll:

So no on to converting some of my dads old programmes to .P

Thanks, Will
Trevor_B
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by Trevor_B »

Just resurrecting this thread for a bit of info

I'm having no luck at all loading from a TZXDuino into Minstrel 3. If I'm reading your post correctly you had to boost the signal by quite a huge amount; is that correct?
I *thought* it was a problem with the signal strength being too high - I've measured the signal at average 2.5v when it "crashes".

In my case it looks like a signal is being received then literally crashing the loading process - I get the wavy lines then screen goes blank ( no video signal being issued - or at least not a signal my Samsung telly or component->hdmi converter can handle - and when the TZXDuino hits 100%, nothing happens. I can hit Break and I get the K screen again (and 0/0)
Is this what you were seeing?

Trev
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1024MAK
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by 1024MAK »

Don’t forget, during loading or saving, a ZX80 or ZX81/TS1000/TS1500 (or clone/compatible) won’t produce a normal video signal. Hence a display like a LCD or a CRT that checks to see if it can detect the correct sync pulses will switch to ‘no signal’ mode.

If the machine does not correctly load the program, often it crashes.

Mark
Trevor_B
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by Trevor_B »

I've just bought an old school B&W telly from ebay (analogue tuning, with composite input) - it'll be just like the old days! I'm aiming to give my original ZX81 a run-out with the TXDuino (hmm - wobbly rampack time!), and also the Minstrel.

I understand what you mean by the screen refresh on lcd/tft screens, but surely once loading completes (or the TZXDuino hits 100% and I wait another 30 seconds) there should be *some* type of screen signal?
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1024MAK
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by 1024MAK »

Yes, if there were no errors during loading, the machine should return to the BASIC prompt (K) or run the loaded program. But if there was an error, then often the machine will crash. If the Z80 is not running a display routine, then there is nothing to generate a video picture.

Until you get it working reliably, it’s best to just try loading short BASIC programs.

Mark
Trevor_B
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by Trevor_B »

My "goto" program is the 1k Chess programme from Artic - that gave all the right signs but never actually loaded.

If I hit break during the fuzzy lines, I get 0/0 -as you would expect.
If I try leaving the load running (from the start, not from mid-point), the fuzzy lines will eventually turn into blank screen (loss of video signal) - then nothing. I noted that if I leave it long enough I can hit break again and sometimes - not always - back to 0/0 but nothing loaded.

I've run out of ideas; the problem is I'm not familiar with the TZXDuino - if I plug headphones into the socket I get the familiar noises down one channel - as you would expect for a stereo headset in a mono socket (the cable from TZXD to Minstrel is original Sinclair mono->mono).
I'm also not familiar enough with Minstrel - so while everything seems to be working, I have no idea if it really is - maybe I've got a dodgy connection in the loading circuit but the fact that I'm seeing a loading "pattern" points me to think it's working - again, I don't actually know.

As I said above - I'm going back to full-on old school later this week; I've bought a geriatric telly, paid a bloody fortune (in old terms) for a bog-standard TDK C60 and I'm hoping my old cassette recorder still works. I'll try saving a tiny program - usual "10 Print "Hello World"" type thing and see if I can reload it. If not, "working" Minstrel becomes amusing paperweight until I can get a way to load and save stuff.
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mrtinb
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Re: ZX81 Clone Tynemouth Minstrel 3

Post by mrtinb »

Trevor_B wrote: Sun Nov 08, 2020 11:16 pm I'm having no luck at all loading from a TZXDuino into Minstrel 3.
If you use your Minstrel with ZX81 ROM, you could build a cheap ZX-Wespi to load programs.

You'll need
  • An ESP32
  • 3 resistors 100R 1K 4K7
  • Taltalum capacitor 47uF 16V
  • 4 short wires
Price around €11.

Image
Last edited by mrtinb on Tue Nov 10, 2020 6:48 pm, edited 1 time in total.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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