Spectrum Computing

Merry Christmas! I hope everyone had a really fun and happy day!

dhr

Hello, Looking up the ZXHD, if I understand right, the only soldering work that's required is to solder a male pin header onto the Rasberry Pi Zero? I have some basic soldering skills, and Raspberry Pi zeros are fairly inexpensive, so I would be happy to attempt this for you. I have successfully don...

Hello, This is a really cool project and I have a lot of respect for your work, thank you for sharing it and the development journey with us. Also, thank you for bringing the TRS80 MC10 to my attention, I had never heard of it before, and I've just spent the past week or so reading about it and play...

Perhaps this program would also be useful for testing basic compilers? It calculates an approximation of the sine function.
https://dusthillresident.ddns.net/sinapprox.tzx

- dhr

Thanks. I actually thought "ok I'll write quicksort, how hard can it be?" and then after writing DIM a(500) and remembering that we don't have either local scope, or bounds checks*, I cried and gave up. (Recursion is enough fun when you have scope.) Haha! The problem of implementing textb...

I was thinking of buying this: https://www.ebay.co.uk/itm/394982944888

But it looks very generic, I can imagine it being a super cheap import kind of thing...

Now the most important thing, buy from a UK company. Don’t get any cheap rubbish from the far East. This is for your own safety. This is something I worry about a lot, it seems to me that a lot of UK sellers are just reselling imported cheap stuff. How can I be sure I'm getting something good? Are ...

One last quick question, what kind of power supply does the spectrum use? I wonder, is it tip negative or tip positive, and what rating of amps, and what voltage does it need? The plug on my Sinclair power brick feels loose and rattles a bit, and generally feels dodgy, so I think it'd be best to rep...

Excellent news! Really well done, and thanks for taking us through the journey. Thank you as well! And thank you also Mark, your knowledge and guidance saved the day, and thank you too everyone who replied and encouraged me through this. Don’t beat yourself up too much, it’s perfectly possible that...

Yes, that's the one. After reading your post I decided to go ahead and solder the socket in and put the nebula in, and, it's working!! https://i.postimg.cc/SJKJwVqs/photo-2023-11-09-02-35-45.jpg Thank you so much for all your help! I'm so amazed to see it working, I was so sure it'd never work again...

I removed the socket and finished desoldering the pins.

Unfortunately, one of the solder pads has broken off. This is presumably going to be a problem. What should I do?

photos:

Here's another photo of the socket currently on the board because I think the first one was unclear.

Does the Nebula appear to fit into the socket it's supplied with correctly? I haven't tried fitting it in the socket it came in, because I worry that it wouldn't be safe to do so for various reasons (risk of damaging the pins of the socket itself, risk of being unable to remove the nebula from the ...

Hello, I got the replacement for IC3 in its socket in the correct orientation, and the Nebula ULA replacement arrived today. I've been trying to fit the nebula in the ULA socket and haven't succeeded. I'm scared to apply much force, but it seems like it's going to need quite a bit of it to squeeze t...

Good thinking, I have a spare toothbrush and some isopropanol, I'll clean the area with it tomorrow.

dhr

Before removal https://i.postimg.cc/fJmVH5bQ/before.jpg After removal https://i.postimg.cc/9wqDHYtT/after.jpg Underside before socket installed https://i.postimg.cc/rzd04qXm/board-before-solder.jpg Socket installed https://i.postimg.cc/grfwq1mK/socket-installed.jpg Underside after socket installed h...

Tonight I'll cut all the remaining pins of IC3, de-solder and remove the legs, and fit the socket and solder it in. I'll take photos before and after and post once I'm done.

dhr

Thank you a lot Mark for all the help and guidance through this. I happen to already have the socket and replacement chip for IC3, and my awesome best friend really kindly wants to get me the modern replacement ULA for Christmas, so hopefully we'll get this spectrum working again eventually. Out of ...

On the PCB pad for IC3 pin 4,, what do you get? Results Black lead to ground, red lead to PCB pad for IC3 pin 4: on 2M range: meter display does not change, displays "1." on 20k range: meter display does not change, displays "1." Red lead to VCC (pin 16 of IC4), black lead to PC...

https://i.postimg.cc/XrRKsfNd/photo-2023-11-04-23-09-34.jpg I've managed to remove the ULA chip, it was very difficult and frightening and I might have slightly bent the pins, see the photo. I hope it's okay. Trying to do the measurement again, meter on 20k Ω, black pin to ground, red pin to the se...

Okay, I cut pin 4 of IC3, and verified that the cut was successful by using the multimeter to test continuity between the pin 4 leg and the solder pad on the board it connects to. Then I repeated the test from before: multimeter on 20kΩ resistance setting black lead to ground, red lead to the now di...

I've got the clippers, the sockets, and the chips from retroleum. I'm going to proceed with the next step now, I'm a little nervous. I'll triple check I have the right IC and the right pin and I'll re-take measurements before cutting the pin, to be certain. While I'm at it, I'd like to ask you Mark ...

I have a real Spectrum Next too, I'd be up for testing it too, even though I'm not very good at games.

dhr

Thanks Mark. I'll post again once I have the clippers and I'm ready to follow the next step.

dhr

Thank you for the recommendations, and thank you a lot Mark for the photos, this helps me a lot with imagining how to approach cutting the legs - I've been nervous about that step. Seeing it like this makes me feel more confident of how to approach it. I just ordered the 16 pin DIL sockets, and two ...