Search found 673 matches

by dfzx
Sat Mar 09, 2024 9:55 am
Forum: Sinclair Miscellaneous
Topic: Sinclair QL Design issues
Replies: 30
Views: 820

Re: Sinclair QL Design issues

If the QL had looked like Rick Dickinson's redefinition, it could have had the mechanism from a clockwork mouse inside it and it still would have flown off the shelves.
by dfzx
Wed Feb 28, 2024 4:45 pm
Forum: Emulators
Topic: ZEsarUX 11 Beta
Replies: 8
Views: 265

Re: ZEsarUX 11 Beta

chernandezba wrote: Wed Feb 28, 2024 3:05 pm 2 Menus. "several screens" is exaggerated
...
Nothing further your honor
I found it complicated and confusing. Sarcastically dismiss the feedback if you like.
by dfzx
Wed Feb 28, 2024 2:46 pm
Forum: Emulators
Topic: ZEsarUX 11 Beta
Replies: 8
Views: 265

Re: ZEsarUX 11 Beta

I think you are exaggerating Are you really serious it’s difficult to get to the menu save screen? :oops: I'm not exaggerating. That STL screenshot took me about 10 minutes to make. Getting to the menu isn't difficult. Getting a screenshot of what I wanted proved very difficult. The problem is that...
by dfzx
Wed Feb 28, 2024 2:05 pm
Forum: Hardware
Topic: New open lower RAM module design (photoessay)
Replies: 98
Views: 2733

Re: New open lower RAM module design (photoessay)

However, I think it should be possible to develop the module on a two-layer PCB, and the price difference here is significant. Earlier in the thread you said the price difference at JLCPCB between an order for 2 layer boards and 4 layer boards is about $5. Here in the UK that's less than the cost o...
by dfzx
Wed Feb 28, 2024 12:20 pm
Forum: Emulators
Topic: ZEsarUX 11 Beta
Replies: 8
Views: 265

Re: ZEsarUX 11 Beta

Here's one, screenshot from my slicer:

Image

Very clever.

The option in ZEsarUX is all but impossible to use though, it took me ages to get that!
by dfzx
Thu Feb 22, 2024 10:14 am
Forum: Showcase your work!
Topic: Replacement Case for Interface 1
Replies: 5
Views: 277

Re: Replacement Case for Interface 1

That's a really nice piece of work, Tom, great job. I was thinking about making something similar to house my recreated ZX Spectrum Expansion System project, but there was a problem I couldn't see an easy answer to: the PCB for a project which is housed in such a case obviously needs an edge connect...
by dfzx
Thu Feb 22, 2024 10:01 am
Forum: Hardware
Topic: Recap Problem.
Replies: 5
Views: 255

Re: Recap Problem.

You wait until you get tin whiskers. Then you'll be puzzled. :lol:
by dfzx
Fri Feb 16, 2024 10:49 am
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

They say that you can pay through paypal with a credit card if you log in as guest but I just cant see that option on my screen I'm pretty sure it means logging into Paypal as a guest. i.e. you don't need a Paypal account. So make your order at Retroleum, click to pay via Paypal, when the Paypal wi...
by dfzx
Mon Feb 12, 2024 1:40 pm
Forum: Programming
Topic: Beating the C compiler...
Replies: 22
Views: 680

Re: Beating the C compiler...

Ah right, I suspected people were doing this unrolled. It just eats in to the RAM, but I think I've got enough space left, plus I can move some of the non-in game graphics in to low RAM. I can probably free up 2kb or so, and I'll give this a go... here is where I find out this is exactly how the co...
by dfzx
Sun Feb 11, 2024 8:55 pm
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

Adrian45 wrote: Sun Feb 11, 2024 8:50 pm SUCCESS !!!
Hurrah!
Adrian45 wrote: Sun Feb 11, 2024 8:50 pm but no sound from spectrums speaker when game playing
OK, power up into BASIC and try

Code: Select all

BEEP 1,0
If you hear the tone from the internal speaker then it's clearly working. If not, that needs looking at as well.
by dfzx
Sun Feb 11, 2024 8:35 pm
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

i dont think its volume ... im thinking it is a hardware issue - would old failing caps possibly effect the signal going into the machine Here's another thread on the topic on another site. Here's another . It isn't out of the question that a capacitor is causing a problem, there's a bit of filteri...
by dfzx
Sun Feb 11, 2024 8:22 pm
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

Are you supposed to hear the noise of software loading from the spectrums internal speaker during loading ? Yes! The tape loader screeching noise is absolutely characteristic of the machine and you should be able to hear it as the tape loads. If you're not hearing that, you're missing out. So is th...
by dfzx
Sun Feb 11, 2024 8:13 pm
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

There's a bit of information in this thread about volume and amplification and the options open to you. Probably other threads as well if you search the archives, it's quite a common subject. If you want to investigate your apparent upper memory issue I suggest you start a new thread with a suitable...
by dfzx
Sun Feb 11, 2024 8:03 am
Forum: Hardware
Topic: Cant load anything
Replies: 41
Views: 1071

Re: Cant load anything

Your machine is a 48K, the DRAM slots in the lower right are all populated. It sounds like it was sold to you as a 16K because the upper RAM isn't working? You might still be able to load a 16K game, though. What device are you using to play the tape? Spectrums require significant volume from the ta...
by dfzx
Thu Feb 08, 2024 9:09 am
Forum: Hardware
Topic: Contended memory with the Z80 in reset
Replies: 14
Views: 686

Re: Contended memory with the Z80 in reset

That's really interesting, I've never heard of a CPU NOP tester... :geek:
by dfzx
Tue Feb 06, 2024 11:11 am
Forum: Programming
Topic: Another ATTRibute scroller, But At Pixel Speeds
Replies: 11
Views: 784

Re: Another ATTRibute scroller, But At Pixel Speeds

And, once past the 4-pixel position, ... And excuse my ignorance as well, please, what is the 4-pixel position? The original thread suddenly started talking about 4 pixels, which didn't make sense to me because attributes are aligned to 8 pixels. Hence I lost track of that discussion. But clearly 4...
by dfzx
Thu Feb 01, 2024 9:53 am
Forum: Hardware
Topic: Timing differences between different versions of 48K ULAs?
Replies: 5
Views: 380

Re: Timing differences between different versions of 48K ULAs?

Some issue one and some early issue two boards have extra daughter boards to correct I/O contention issues. This was then incorporated in later issue ULAs. Some may have escaped modification... Is that what's going on here ? I noticed that auction yesterday, and was rather surprised to see an uncas...
by dfzx
Tue Jan 30, 2024 12:16 pm
Forum: Sinclair Miscellaneous
Topic: ZX Spectrum code on The IT Crowd DVD ?
Replies: 39
Views: 1393

Re: ZX Spectrum code on The IT Crowd DVD ?

PROSM wrote: Tue Jan 30, 2024 11:53 am again, this has been a fruitless endeavour.
Nevertheless, I am in utter awe of your audio signal preprocessing abilities...
by dfzx
Fri Jan 26, 2024 12:39 pm
Forum: ZX Spectrum Next
Topic: ROTW units shipping soon
Replies: 10
Views: 795

Re: ROTW units shipping soon

SkoolKid wrote: Fri Jan 26, 2024 11:50 am And now I have an import duty/customs clearance bill of over $100 to pay before I can receive the package. :(
You would have always expected that, though, would you not?
by dfzx
Fri Jan 26, 2024 10:21 am
Forum: Hardware
Topic: Contended memory with the Z80 in reset
Replies: 14
Views: 686

Re: Contended memory with the Z80 in reset

Many thanks for all the help. I'm using an RP2040 attached to the edge connector to sample signals and understand what's going on with the CLK line. Nothing is taking over the machine, and the Spectrum isn't expected to be doing anything useful while I conduct these experiments. I was seeing odd val...
by dfzx
Thu Jan 25, 2024 7:51 pm
Forum: Hardware
Topic: Contended memory with the Z80 in reset
Replies: 14
Views: 686

Re: Contended memory with the Z80 in reset

Thanks Mark. Unfortunately, in my attempt at brevity, I didn't quite ask the question I wanted to, which was this: If I assert the Z80's /RESET pin (via a device on the Spectrum's edge connector), and hold that /RESET pin asserted , am I guaranteed that memory contention will never happen and the UL...
by dfzx
Thu Jan 25, 2024 5:12 pm
Forum: Hardware
Topic: Contended memory with the Z80 in reset
Replies: 14
Views: 686

Contended memory with the Z80 in reset

If I assert the Z80's /RESET pin (via a device on the Spectrum's edge connector) am I guaranteed that memory contention will never happen and the ULA will never slow the clock from 3.5MHz?
by dfzx
Wed Jan 24, 2024 1:47 pm
Forum: Hardware
Topic: Diagnostics card help.
Replies: 27
Views: 991

Re: Diagnostics card help.

If it's the chip that handles data bit D0, D1 or D2, that's enough for the ROM memory check to fail the 'upper' RAM, the machine should then try to operate as a 16K system. Would it be adequate to clip the data pin on the upper DRAM chip which supplies, say, D0? The system would then see that bit a...
by dfzx
Mon Jan 22, 2024 4:24 pm
Forum: Hardware
Topic: RAM Desoldering Tips
Replies: 8
Views: 373

Re: RAM Desoldering Tips

You're doing everything right. My conclusion from my own attempts to get those ICs out is that sometimes, quite often in fact, it's just not possible. A desoldering gun is more convenient than a solder sucker, but it's not a magic weapon. The problem as I see it is that when the IC was inserted, its...
by dfzx
Mon Jan 15, 2024 5:33 pm
Forum: Hardware
Topic: ZX Spectrum - Issue 4B - problem between chair and keyboard
Replies: 10
Views: 467

Re: ZX Spectrum - Issue 4B - problem between chair and keyboard

So, booting with the external ROM card sees the Spectrum come up normally? The video seems to demonstrate that? Is the machine stable for that minute or so, in that you can type stuff and make it BEEP, etc? If it seems OK, then that seems to point to a building heat issue. Can you find any device wh...