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#91
Hello everyone. I was wondering if someone could assist please.

I have bought a very nice condition CTM644 and being working for a few days and now its just shows a horizontal bright line when I turn on my Amstrad, nothing when off. This happened out of the blue with no noises or warning.

I read this could be vertical collapse. I do have a spare working CMT644 mainboard which I could swap but I would like to try and fix it.

Any help would be appreciated as it was a beautiful picture.

CTM644

Mainboard

Thankyou
#92
A
Programming / Re: Bootstrapping from FAT for...
Last post by andycadley - 16:30, 16 May 24
Quote from: Benedikt on 15:59, 16 May 24In that case I will have to resort to some hideous CALL trickery, because |CPM only works with drive A and I need drive B.
Hopefully I can come up with something that is short enough to be usable.

I'm not really sure you need any trickery. You can just RUN a binary file, provided the header is correctly set up for it.
#93
B
Programming / Re: Bootstrapping from FAT for...
Last post by Benedikt - 15:59, 16 May 24
Quote from: Prodatron on 22:31, 15 May 24But you can always reserve clusters on a FAT device using the FAT itself without assigning them to a file (a PC then may want to repair the disc :) ).
Reserving clusters by putting a file there sounds like a more intuitive and more robust option.
Ideally a hidden, write-protected system file or something.

Quote from: andycadley on 22:49, 15 May 24The only way from BASIC is |CPM which loads track 0, side 0 sector &41. It will only load 512 bytes though (whatever is booted is then expected to load the rest).
In that case I will have to resort to some hideous CALL trickery, because |CPM only works with drive A and I need drive B.
Hopefully I can come up with something that is short enough to be usable.
#94
avatar_Shaun M. Neary
Games / Re: Adapting loading screens t...
Last post by Shaun M. Neary - 15:23, 16 May 24
Quote from: ervin on 02:46, 16 May 24I always really liked the original CPC loading screen, even if Trantor looks like David Lee Roth!  :laugh:
Your new version looks great.
Oh thanks. Now anytime I load that up, all I'll hear is "This... must... be... just... like... living in par-a-dise!", and that was overplayed enough in 1988  :laugh: :laugh:
#95
48Msps :-X
Although zt-703 and ... I dreamed about Rigol
#96
Quote from: Bryce on 14:18, 16 May 24Bryce.
Ouch. That would be a bit disappointing. It's the one suggested on page 2 of this thread. 

The spec shows 10MHz. Am I misunderstanding it? (Quite possible.)
#97
avatar_HAL6128
Programming / Re: Rasm Z80 assembler
Last post by HAL6128 - 14:27, 16 May 24
Hello @roudoudou,

just two quick questions maybe I don't exactly understand your docu in RASM regarding calling a struct:

It says:

STRUCT nom_du_prototype, nom_de_la_variable / ENDSTRUCT

When STRUCT is used with 1 parameter (name), the following labels will be used to declare the structure, in particular its indexes 
When STRUCT is used with 2 parameters (type_name+struct_name), a structure is created of type_name and will be called structure_name

Although RASM allows you to put anything inside the declaration of a structure, the practical use is to declare labels and via the data definition instructions, a field size. It is not necessary to fill in a value in the DEF
struct st1
  ch1 defw
  ch2 defb
endstruct
struct metast1
  struct st1 pr1
  struct st1 pr2
endstruct
struct metast1 bigst ; instanciation de metast1 en bigst
ld hl,bigst.pr2.ch1 ; récupération de l'adresse absolue d'un membre de bigst
ld a,(hl)
ld a,(ix+metast1.pr2.ch1 ; utilisation de l'offset du champ via la définition de la structure (pas besoin d'instancier pour cet usage)

Q1: This part "ld hl,bigst.pr2.ch1" refers to second pointer (first struct) of the second pointer (second struct) included in the second struct? It's nested somehow, isn't it?

Q2: Is there also a D24 (3 byte member) within RASM struct available?
#98
Quote from: mmldrm on 12:23, 16 May 24Finally the 74LS02 has arrived!

I will try the above tests too, if I understand them.  :o

My oscilloscope is a Zoyi ZT-702S: https://zoyitools.com/product/zt-702s/

I found it for £43, and figured it's something I can use for years after this. This is true for the breadboard and components I bought for the tests - I like playing with electronics and would like to do more hardware projects in the future.

If these tests from @McArti0 can reduce the number of chips that I desolder and replace, I am less likely to destroy the motherboard in the process. Unorthodox, but I'm happy to proceed with caution on this.

Thanks for staying with me this far on the journey. I know there is a variety of opinions on the path we have taken. :)

The scope is ok for basic "signal present" checking, but only up to about 3MHz for proper diagnosis. That's a bit on the low side even for retro computer repair.

Bryce.
#99
Quote from: McArti0 on 13:26, 16 May 24Ok. Make OR Gate on breadbord. (From 2 NOR gate in 74Ls02). ;)
I could do this when I was 18. 😅 I'll go read up on it and get back to you. 🫡 
#100
Ok. Make OR Gate on breadbord. (From 2 NOR gate in 74Ls02). ;)
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