ZX Spectrum Upper RAM Diagnosis, Repair and Service | Machine Code! | Z80! | Opcodes!
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- Опубликовано: 11 июл 2024
- I got carried away with this one again, let's get into the ROM, let's get into Opcodes, let's get into Z80 architecture, let's fix and service this machine!
Who else has used the command PRINT PEEK 23732 + 256*PEEK 23733?
We get side tracked today into Z80 processes and machine code to understand why this is helpful and how it comes to be in memory location 23732.
If you enjoyed this then check out:
Composite Mod Guide - • How to Composite Video...
DCDC Mod Guide - • Issue 3 ZX Spectrum 48...
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I love that ROM Disassembly book, I learnt so much from it back in the day - including how to write tape load/save code, which later allowed me to port code to the Amstrad CPC. So well documented and useful, additionally showing how great the Sinclair coders were to get what they did out of this machine.
Couldn't agree more
Tip for getting that glue off - spray WD40 on it... leave it for a few minutes.. then it scrapes away super easy. Only downside is your room will stink of WD40 afterward!
That's a last resort! It does work though you're right
You would be better using isopropyl alcohol as it will completely evaporate and WD40 will leave use a residue.
Nice. And in the next video, full screen machine code scrolling... :-)
On it!
Great informative video 👍
Why thank you
Going to try that ram check on my next one, thanks!
Let me know how it goes
Superb stuff!
I've not considered putting the cap inside the modulator can. Might work better with some taller ones I have here.
Let me know how it goes if you try it!
It's really interesting! Love the peek commands. Do you think this world work on other Z80 computers? Thanks for sharing
You can always read the memory locations associated with ROM and RAM as long as the commands exist. Decoding then just depends on the opcode table of the CPU you're working with
In a Speccy I work on ATM I have changed the ULA socket to a precision low-profile one (ico640lgt). Then a 1.5mm M.2 SSD heatsink fit in the case.
Interesting, thanks for the tip
I loved my spectrum 48 in those days. I live in Holland and ordered it in England. Also my later bought double 3,5" diskette drive (blue, cannot remember the name) came from England. I used it for wordprocessing of our club periodical and the standings of the club championship motocross. I loved using machine code and succeeded in sorting arrays by swichting pointers. Who knows the diskdrive brand?
Lover the explanation, but please turn the background music down
Thanks for the feedback, I always wonder where the sweet spot is
what do you think will be ok to change ztx213 by bc327-25?
sinclair.wiki.zxnet.co.uk/wiki/Replacement_Components
ZTX213 can be replaced with BC251, BC307, BC512, BC557
@@HappyLittleDiodes thanks a lot ❤️
cool, this is my computer, the display has more noise on it than before, I'm using an upscaler thing so I can use it in a modern TV that doesn't have composite, and I've lost the little adapter thing years ago. the faceplate was battered, and wasn't staying down, I've ordered a new one from evil bay in chrome. the thing works. alas my hand now spans the whole keyboard so no games played using "Q, A, O, P and Space to fire" Now to fix my DivMMC as it's corrupted the SD card.
The noise might be due to the upscale thingy. You can get a scart adapter cheap as chips that could be a better result. Or even a zxhd!
@@HappyLittleDiodes Yes and a zxhd cost more than god's tears. so no.
Hi, I got number 7 upper ram chip out. I`ve noticed pin 11 has a link to the other pin 11`s on the other chips. But under chip 7 the link is only going half way across. Either I broke it or it is the fault. It`s hard work with old eyes lol. I`ll update when the chip arrives. :)
Dig the multimeter out and check continuity across all the chips. All of the pins should have continuity with the exception of 2, the data pins
Since I got 64 when I poked 0. Chip 8 must of been working so the link must of been ok then otherwise I would of got 192. Anyway I`ll just join them together with a wire. It looks hard work to put a trace back on the board.
@@damianbutterworth2434 yes I like to use enamelled wire on the underside
@@HappyLittleDiodes oh I was going to link on top. Good idea. I`ll do it underneath. Thanks again for the tip. I own you a beer.
Niiiiiiiiiice!!! This content desperately needs 'promosm'!!!
I am 60 in 2022 and worked for LMT Computers Ltd in the mid to late 80s (SPD1 Disk Interface). I then went on to work with MGT to help create the DISCiPLE and some of the Sam Coupe. I was doing this many years ago, but moved away from my "hands on" technical roots, but still in IT. For those that are interested see this ruclips.net/video/WBA6svOyWb8/видео.html to learn about Little and Big EDNIAN. It is fantastic to see something that I grew up with still giving pleasure to people. It always amused me that Sinclair bought "duff" ram chips that only 1/2 worked and that there was a selector on the PCB to say which part did not work. And having that -5V and +12V inverters to power those really old RAM chips doh! We used to replace the RAM with +5V only chips and ditch the inverters. Keep up the good work!
Thanks! There is an option to replace the 4116 with 4532 chips and do a bit of pin bending and adjusting, it's a bit ugly though, maybe there's some fun to be had making this mod invisible