Search found 3151 matches

by 1024MAK
Wed May 22, 2024 12:36 pm
Forum: Hardware
Topic: Is vintage hardware better able to survive an EMP event?
Replies: 14
Views: 312

Re: Is vintage hardware better able to survive an EMP event?

Don't forget, the human (and various other animal) nervous system also uses electrical signals...

Mark
by 1024MAK
Tue May 21, 2024 4:48 pm
Forum: Hardware
Topic: Is vintage hardware better able to survive an EMP event?
Replies: 14
Views: 312

Re: Is vintage hardware better able to survive an EMP event?

If that happens, best get your bids in fast for some space in an underground cave/mine/tunnel or similar... :lol:

Mark
by 1024MAK
Tue May 21, 2024 2:36 pm
Forum: Hardware
Topic: Is vintage hardware better able to survive an EMP event?
Replies: 14
Views: 312

Re: Is vintage hardware better able to survive an EMP event?

Atari STFM and various other computers sold in the USA or other countries where EMI regulations are/were quite strict will also have or likely have either steel cases or internal steel shielding. However, there are still plenty of holes in these cases/shields. Plus of course the mains cable and thos...
by 1024MAK
Tue May 21, 2024 11:57 am
Forum: Hardware
Topic: Is vintage hardware better able to survive an EMP event?
Replies: 14
Views: 312

Re: Is vintage hardware better able to survive an EMP event?

It's semiconductors that are most affected, that would include Z80 and 6502 processors, DRAM, SRAM etc. Equipment that only uses resistors, relays, coils, non-electronic regulators, motors etc. may well survive if far enough away. Normal military grade semiconductors would also die, as these normall...
by 1024MAK
Mon May 20, 2024 11:02 am
Forum: Graphics
Topic: Be careful - image flipping won'r protect you!
Replies: 16
Views: 621

Re: Be careful - image flipping won'r protect you!

What is a copy and what is not a copy? What is a derived work? What about an item inspired by another item that is copyrighted? Ultimately all humans learn by copying. If a child decided to paint a picture of a photo, would that be a copyright infringement? Copyright is only supposed to protect the ...
by 1024MAK
Sat May 18, 2024 12:30 pm
Forum: Hardware
Topic: Issue 4B, 12V power missing
Replies: 5
Views: 200

Re: Issue 4B, 12V power missing

TR4 is a bipolar NPN transistor, so it’s more useful to refer to the three terminals/leads by the junction names: c - collector, b - base, e - emitter. https://i.postimg.cc/Jt653ykd/E209867-A-D2-DF-4781-A82-D-9-E1246-AD0-D48.jpg In this circuit (TR4), the emitter is connected to the 0V/GND/ground ra...
by 1024MAK
Wed May 15, 2024 8:15 pm
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

Thank you for reporting back :D

Glad that you have found the problem and now have a working board :dance

And it’s good to confess mistakes. It allows other members to learn. You are not the first and will not be the last to suffer from bent pins...

Mark
by 1024MAK
Wed May 15, 2024 12:27 pm
Forum: Hardware
Topic: Issue 4B, 12V power missing
Replies: 5
Views: 200

Re: Issue 4B, 12V power missing

Most likely TR4 (ZTX650) has died. A ZTX651 or a ZTX653 can be used as a replacement. It's also possible that TR5 has died. The most common causes of TR4 becoming damaged are edge-connector abuse (expansion/interface being removed or fitted while the computer is powered on or other short circuit), o...
by 1024MAK
Wed May 15, 2024 10:55 am
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

In the last set of tests, the ULA is not fitted, hence there is no AC signal, the circuit is only operating in a static / DC state. This is primarily to confirm that in a static state it is working okay. It's much easier to pick up basic faults in a static state. As to what a digital meter will show...
by 1024MAK
Wed May 15, 2024 9:51 am
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

See comments in GREEN and RED No ULA R73 5.03 Right, 2.81 Left - Okay R24 2.93 Right, 0.87 Left - I would expect R24 right to be approximately the same as R73 left Base 0.83, collector 0, Emitter 0 - Okay Pin 6 CPU 0 - Okay R25 5.03 Right, 0.83 Left - R25 left should be 0V or very close to 0V Can yo...
by 1024MAK
Tue May 14, 2024 3:54 pm
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

Nothing springs out as being wrong with the Z80 clock part of the circuitry.

Mark
by 1024MAK
Tue May 14, 2024 2:49 pm
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

Can you please disconnect the power, then remove the ULA (I presume all chips are in sockets). Power up again and retest the voltages that you did in your last post. Next, power off again. Now use a test lead to connect R73 left lead to a 0V/ground point. Please ensure you have the correct lead of R...
by 1024MAK
Tue May 14, 2024 12:43 pm
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

Here's some screenshots from my PicoScope of one of my ZX Spectrum boards. https://i.postimg.cc/TLQ6DTqJ/ZX-Spectrum-Z80-clock-circuit-waveforms-1.png https://i.postimg.cc/145PZNsC/ZX-Spectrum-Z80-clock-circuit-waveforms-2.png Blue waveform is TR3 base. Voltage scale is shown on the left of the scre...
by 1024MAK
Tue May 14, 2024 11:42 am
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

It looks like your waveform is swinging from positive to negative, which surely can't be right, can it? I suspect that AC coupling mode is selected. For this circuit DC coupling mode should be used unless the 'scope used cannot process DC signals with a negative component. Also the timebase needs t...
by 1024MAK
Tue May 14, 2024 11:15 am
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

ZX Spectrum Z80 clock circuit. This is the circuit: https://i.postimg.cc/7J55WJf6/4-E0-FBB34-ED60-4049-9-B62-BF7-FBC900461.png https://i.postimg.cc/XNMLH8DD/4-E0-FBB34-ED60-4049-9-B62-BF7-FBC900461.png?dl=1 The reason why this circuit is used is because the ULA cannot output a rail to rail signal (m...
by 1024MAK
Mon May 13, 2024 10:56 am
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

Also a 'scope waveform of the base and the collector of TR3 if you have a dual channel oscilloscope. Note that the 'scope must have a bandwidth of 25MHz or better, ideally 50MHz or better.

Mark
by 1024MAK
Mon May 13, 2024 10:39 am
Forum: Hardware
Topic: CPU not starting
Replies: 33
Views: 651

Re: CPU not starting

The type of transistor used in the clock circuit (TR3) is critical. If the turn off time of the transistor is too long, the voltage at the collector will stay low or the output pulse will be short and distorted. ZTX313 have been obsolete for years and the other main substitute is also discontinued. ...
by 1024MAK
Sat May 11, 2024 12:15 pm
Forum: Website
Topic: QAOP bust again?
Replies: 18
Views: 223

Re: QAOP bust again?

Last time I tried on a iPad mini, the site would not work (it did earlier in the year). I no longer have this iPad. On the device that I am currently using, it does work (the link that Peter provided) and just going to the site via its URL so that you drop into BASIC. https://i.postimg.cc/JswcC1cn/S...
by 1024MAK
Sat May 11, 2024 12:00 pm
Forum: Website
Topic: Issues changing email address on other site (WoS)
Replies: 31
Views: 673

Re: Issues changing email address on other site (WoS)

Okay, here's screen shots of those pages: https://i.postimg.cc/Z9pQz7dk/Screenshot-20240511-115151-kindlephoto-1591083851.png https://i.postimg.cc/0MvBkYYz/Screenshot-20240511-115226-kindlephoto-1591218515.png https://i.postimg.cc/wykb7120/Screenshot-20240511-115249-kindlephoto-1591176133.png Mark
by 1024MAK
Fri May 10, 2024 4:26 pm
Forum: Website
Topic: Issues changing email address on other site (WoS)
Replies: 31
Views: 673

Re: Issues changing email address on other site (WoS)

Sorry if my poor English doesn't completely understand what you are saying. Are you suggesting me to DM/PM you? If Lee does communicate with me, he is very likely to want to know your old email address and your new email address. It is entirely up to you if you want to do this. I am just trying to ...
by 1024MAK
Thu May 09, 2024 5:21 pm
Forum: ZXDB Discussion
Topic: Manic Miner/Jet Set Willy no longer available
Replies: 49
Views: 1834

Re: Manic Miner/Jet Set Willy no longer available

Cheez26 wrote: Thu May 09, 2024 3:32 pm I didn't think Elite Systems is still a thing in this scenario...
The company is still registered: https://find-and-update.company-informa ... y/01840901

Mark
by 1024MAK
Tue May 07, 2024 4:43 pm
Forum: Website
Topic: Issues changing email address on other site (WoS)
Replies: 31
Views: 673

Re: Issues changing email address on other site (WoS)

I don't know any details on the forum software used by WoS, but on phpBB forums, the powers between moderators and administrators can be very different. Even the powers given to the moderators can vary. A standard moderator can only ban users, not change their details. But the administrators can giv...
by 1024MAK
Tue May 07, 2024 4:36 pm
Forum: Programming
Topic: Bank switching issue
Replies: 38
Views: 1524

Re: Bank switching issue

Well, it all depends on what you are trying to do. Which takes up the most space, executable code or data?

The all RAM mode is only available on the +2A, +2B and +3 models and was presumably intended for CP/M use.

Mark
by 1024MAK
Tue May 07, 2024 4:32 pm
Forum: Website
Topic: Issues changing email address on other site (WoS)
Replies: 31
Views: 673

Re: Issues changing email address on other site (WoS)

I'm happy to add other users that are unable to log in to the WoS forums to my topic on WoS forums.

Please quote your WoS forum user name. And it helps if you PM / DM your old and new email addresses in case Lee or another WoSf admin asks for them.

Mark