Search found 1245 matches

by mrtinb
Fri Sep 11, 2020 7:34 am
Forum: WANTED
Topic: ZX81 ULA or ULA Replacement
Replies: 12
Views: 641

Re: ZX81 ULA or ULA Replacement

The ULA for the ZX81 has currently two replacements: Andy’s ULA vLA81 These are often cheaper than an original ULA, as the original ULAs are getting rarer. The replacement ULA often has added some of these features: M1NOT mod to enable machine language in high memory, that Sinclair intended for data...
by mrtinb
Sun Sep 06, 2020 11:05 pm
Forum: GAMES
Topic: 1 Karat
Replies: 4
Views: 2021

Re: 1 Karat

New hiscore in 1 Karat

Image
by mrtinb
Sun Sep 06, 2020 5:16 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 852

Re: ZX81 generates high pitched sound on CRT

I'm grateful for all the help you all give me. I havn't had time to test all suggestions yet.
by mrtinb
Sun Sep 06, 2020 7:47 am
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 852

Re: ZX81 generates high pitched sound on CRT

As mentioned in the first post, there is no sound when software that uses WRX graphics is used.

So it is software affected. And remember: Most of the hardware in ZX81 is software. ;-)
by mrtinb
Sat Sep 05, 2020 10:29 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 852

Re: ZX81 generates high pitched sound on CRT

It works with the composite output of a Raspberry Pi, without the noise.

My plan is to use my Lambda 8300 with the custom ZX81 ROM. This will work without the noise.

Maybe I can make a modified ROM for the ZX81, that does not produce the sound. :-/
by mrtinb
Fri Sep 04, 2020 11:33 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 852

Re: ZX81 generates high pitched sound on CRT

The sound does not change at all changing the contrast and brightness. And here is a picture without the lights turned off. Here the monitor is powered off as well. https://trello-attachments.s3.amazonaws.com/598af660300e0d55b35f5755/5a36e7929ce3cfa9702728e9/31620e482c7645106b270984f1bc0382/image.jp...
by mrtinb
Fri Sep 04, 2020 9:51 pm
Forum: Development
Topic: Splash Scree
Replies: 7
Views: 1013

Re: Splash Scree

mrtinb, I am unfamiliar with MTASM and am curious about the graphics characters at the end of each line of the program. What do they mean? zx-splsh.jpg These chars are not shown, when you edit the source inside the assembler. You are not supposed to display the source this way, but it was just a li...
by mrtinb
Fri Sep 04, 2020 9:40 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 852

Re: ZX81 generates high pitched sound on CRT

I have now opened the back of the monitor. I have taken 2 pictures of the back if the tube in operation. One picture was taken with no composite input, and the other when the text mode of ROM display routine is making the sound. You can see it is shining brighter and more blue, when the text mode is...
by mrtinb
Fri Sep 04, 2020 9:10 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 852

Re: ZX81 generates high pitched sound on CRT

Eagle CSS40 System CSS-14 Series, CCTV System. Monitor Model P701 (HVM29XXAS4C).

Can't find anything about it.

Sound is off, when LISTing i FAST-mode, but the resumes, when picture is drawn again.
by mrtinb
Fri Sep 04, 2020 2:59 pm
Forum: WANTED
Topic: ZX81 ULA or ULA Replacement
Replies: 12
Views: 641

Re: ZX81 ULA or ULA Replacement

Hello again, Sorry but I couldn't get all information about it. Please to check : http://blog.retroleum.co.uk/electronics-articles/nebula-spectrum-ula-chip-replacement-module/ May it helps you? write to Phill, he will answer you properly. The price is pretty low compared with other solutions. Cheer...