Search found 3104 matches

by 1024MAK
Wed Mar 13, 2024 11:13 pm
Forum: ZX80 & ZX81
Topic: WRX True High Resolution Graphics
Replies: 4
Views: 429

Re: WRX True High Resolution Graphics

For the game, see also
https://www.sinclairzxworld.com/viewtop ... f=11&t=289
and
https://www.sinclairzxworld.com/viewtop ... f=4&t=1317

For the details on how hires works, this site is a bit more readable (apart from the ASCII diagrams) ;-)

Mark
by 1024MAK
Sun Mar 10, 2024 2:23 pm
Forum: Hardware
Topic: When tapes fail due to age
Replies: 9
Views: 461

Re: When tapes fail due to age

Sounds like a lack of volume issue.

Mark
by 1024MAK
Tue Mar 05, 2024 2:12 pm
Forum: Hardware
Topic: very low 'volume' from 'speaker'
Replies: 6
Views: 183

Re: very low 'volume' from 'speaker'

That's diode D13 (1N4148).

Speakers unless the cone is damaged, either work normally or are completely broken.

Mark
by 1024MAK
Thu Feb 29, 2024 3:31 pm
Forum: Hardware
Topic: New open lower RAM module design (photoessay)
Replies: 98
Views: 2734

Re: New open lower RAM module design (photoessay)

And the last part of that post appears to have got lost. It should have ended:

'It will be hard to work out exactly what the problem is".

Mark
by 1024MAK
Wed Feb 28, 2024 8:25 pm
Forum: Hardware
Topic: New open lower RAM module design (photoessay)
Replies: 98
Views: 2734

Re: New open lower RAM module design (photoessay)

Okay, best if we calm down. Right, so there are some points I want to comment on. First off, we now know far more about how high speed digital signals are affected on PCBs now, compared to the 1980s. And Sinclair did have problems. Yes, the ZX Spectrum was okay, but the QL board had to be redesigned...
by 1024MAK
Sat Feb 24, 2024 2:50 pm
Forum: Hardware
Topic: Question... 2nd joystick button?
Replies: 9
Views: 257

Re: Question... 2nd joystick button?

I'm curious to know whether the Spectrum can make use of a 2nd joystick button (or Master System pad buttons for example)? As Andy says, it depends on the actual joystick interface. By this, I mean both the type and the actual revision/version. This is especially relevant for Kempston or Kempston c...
by 1024MAK
Fri Feb 23, 2024 7:26 pm
Forum: Hardware
Topic: Composite to Scart - What am i doing wrong
Replies: 8
Views: 235

Re: Composite to Scart - What am i doing wrong

You might be able to fit a composite connector to that monitor, it has markings for cvbs input, on a lot of those rebadged Philips (cm8833) monitors you can. Will not help if it lacks the PAL colour decoder circuitry... Does scart need voltage for it to switch? "Notice the +5 volts applied to ...
by 1024MAK
Fri Feb 23, 2024 9:22 am
Forum: Hardware
Topic: Composite to Scart - What am i doing wrong
Replies: 8
Views: 235

Re: Composite to Scart - What am i doing wrong

Although most TVs support composite video inputs on their SCART sockets, not all monitors do. So the first thing is to check any documentation for your monitor. The fact that you can get an monochrome red, green or blue image if you use one the red, green or blue RGB inputs without having to provide...
by 1024MAK
Thu Feb 22, 2024 12:31 am
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

Thanks for reporting back ;)

Have fun :D

Mark
by 1024MAK
Wed Feb 21, 2024 11:45 pm
Forum: Hardware
Topic: Recap Problem.
Replies: 5
Views: 256

Re: Recap Problem.

Beware, the thinnest hair width solder splash can cause utter chaos... :twisted:

Mark
by 1024MAK
Tue Feb 20, 2024 10:16 pm
Forum: Hardware
Topic: Diagnosing strange 'black screen' video issue
Replies: 6
Views: 234

Re: Diagnosing strange 'black screen' video issue

Replacing IC14 is unlikely to make much, if any difference to the dot-crawl. The real problem is a design limitation. The 16K/48K/+ uses two different oscillators to produce the pixel clock and the colour sub-carrier/encoder. Hence they are not locked to each other. That's the problem (well, the mai...
by 1024MAK
Tue Feb 20, 2024 6:55 pm
Forum: Hardware
Topic: Making a Scalextric lap counter
Replies: 20
Views: 558

Re: Making a Scalextric lap counter

Yeah, it's now okay :D

Will watch it later.

Mark
by 1024MAK
Tue Feb 20, 2024 6:53 pm
Forum: Website
Topic: 2 second DELAY is FREAK ....
Replies: 5
Views: 415

Re: 2 second DELAY is FREAK ....

See also this topic.

Probably best to post any comments about this problem in the linked to topic rather than continue this topic.

Mark
by 1024MAK
Tue Feb 20, 2024 6:51 pm
Forum: Website
Topic: "Sorry but you cannot use search at this time..."
Replies: 16
Views: 515

Re: "Sorry but you cannot use search at this time..."

The real problem here, is that many built in functions use the search even though the user or member may not be aware that said function is using the search system. For example, using the quick link 'active topics' (top left drop down menu) uses the search system. The second problem is that some oth...
by 1024MAK
Tue Feb 20, 2024 6:33 pm
Forum: Hardware
Topic: Making a Scalextric lap counter
Replies: 20
Views: 558

Re: Making a Scalextric lap counter

No problem, I like helping people.

You may want to check the video settings, it's currently not working, instead we see a "this video is private" message...

Mark
by 1024MAK
Tue Feb 20, 2024 10:51 am
Forum: Hardware
Topic: Incorrect voltages on Spectrum 3b
Replies: 35
Views: 742

Re: Incorrect voltages on Spectrum 3b

The data lines and the keyboard input lines to the ULA are all pulled high by resistors, so yes, without anything to drive them, they should be around VCC (+5V). Which address lines on the ULA socket did you test? IC3 and IC4 will affect A0 to A6. A14 and A15 should be the same level as on the Z80 s...
by 1024MAK
Mon Feb 19, 2024 10:52 pm
Forum: Hardware
Topic: Incorrect voltages on Spectrum 3b
Replies: 35
Views: 742

Re: Incorrect voltages on Spectrum 3b

Note, where I quote 5V, this is assuming your VCC / +5V rail is exactly 5V. So if this rail is 4.9V and you get 4.9V where I state 5V, that's fine. With TR3 removed, the ULA and Z80 not fitted: ULA pin 32 = 5V Z80 pin 6 = 5V TR3 base = 5V TR3 collector = 5V TR3 emitter = 0V Current test (between the...
by 1024MAK
Mon Feb 19, 2024 6:36 pm
Forum: Hardware
Topic: Diagnosing strange 'black screen' video issue
Replies: 6
Views: 234

Re: Diagnosing strange 'black screen' video issue

So, from what I can tell, IC1, the ULA and IC14, the LM1889 are okay.

The problem appears to be TR1, R52 or the components or PCB tracks in this part of the circuit.

Mark
by 1024MAK
Sun Feb 18, 2024 7:14 pm
Forum: Hardware
Topic: Diagnosing strange 'black screen' video issue
Replies: 6
Views: 234

Re: Diagnosing strange 'black screen' video issue

Hello Snipey and welcome :D Question, was this failure mode present before you started work on this board. Specificity, before you renewed TR1, TR2 and the axial electrolytic capacitors. - in the mean time, the Spectrum remains fully functional, even after the screen is black Can you please expand o...
by 1024MAK
Sun Feb 18, 2024 12:02 pm
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

That, but also because of how the ROM code detects how much RAM is present. The ROM is not testing to see how much working RAM there is, it's only testing to see how much RAM there is. This is an important distinction, as the test used assumes that all RAM that is present is fully working. The ROM c...
by 1024MAK
Fri Feb 16, 2024 2:45 pm
Forum: Sinclair Miscellaneous
Topic: Who do you buy your spare parts from
Replies: 8
Views: 360

Re: Who do you buy your spare parts from

Adrian45 wrote: Thu Feb 15, 2024 9:05 pm Just spent 20 min on Retroleum.co.uk , 16 items in my basket , went to pay and they only take paypal.
Have you tried contacting the site owner to ask about paying by credit card. He is normally very helpful.

Mark
by 1024MAK
Fri Feb 16, 2024 2:42 pm
Forum: Games/Software
Topic: How big should new Speccy games be? 48k? Bigger? Release 2 versions?
Replies: 67
Views: 1647

Re: How big should new Speccy games be? 48k? Bigger? Release 2 versions?

Oh, and I feel that the small minority with an "80K" RAM upgrade are being left out :cry: Technically it is also possible to have a 32K Speccy (16K rubber key with 16K of expansion RAM). I don't know if anyone ever made expansion packs or fitted suitable DRAM chips internally for this thou...
by 1024MAK
Fri Feb 16, 2024 2:38 pm
Forum: Games/Software
Topic: How big should new Speccy games be? 48k? Bigger? Release 2 versions?
Replies: 67
Views: 1647

Re: How big should new Speccy games be? 48k? Bigger? Release 2 versions?

Yeah but, no, but... Are we speaking about "straight" AY sound chip data, music notation, samples or what? 6K bytes of AY sound chip music data <> as data for samples. Then there is the mass storage system being used. Real tape LOADing on a real ZX Spectrum is rather slower than being LOAD...
by 1024MAK
Thu Feb 15, 2024 7:55 pm
Forum: Website
Topic: Forum e-mail alerts corrupted?
Replies: 7
Views: 222

Re: Forum e-mail alerts corrupted?

Last one I had was okay...
Image

Mark
by 1024MAK
Thu Feb 15, 2024 4:30 pm
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

No problem.

It's a lot easier when a DRAM chip fails and produces a binary 1 regardless. When they produce 'random' outputs or bianry zeros, it's a bit more tricky.

Mark