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#91
H
Technical support - Hardware related / CPC 464 doesn’t boot, shows bl...
Last post by hatman72 - 19:33, 12 July 25Hi everyone, I'm hoping that someone can suggest what might be wrong with this early 464 with a 40007 Gate Array.
When I start it always ends up at this screen with alternating blocks of 128 characters in light blue and purple. There is no beep if I press delete. There seems to be lots of activity on the board and no chips seem to be getting excessively warm. The problem is that since only the CPU and GA are socketed I don't want to start desoldering chips at random as I do not have a desoldering gun.
The computer came to me this way and has been stored in a loft. I have no idea whether it was working when it was put there.
When I start it always ends up at this screen with alternating blocks of 128 characters in light blue and purple. There is no beep if I press delete. There seems to be lots of activity on the board and no chips seem to be getting excessively warm. The problem is that since only the CPU and GA are socketed I don't want to start desoldering chips at random as I do not have a desoldering gun.
The computer came to me this way and has been stored in a loft. I have no idea whether it was working when it was put there.
#92
General Discussion - Introductions / Re: New 3" disks? Floating an ...
Last post by ZorrO - 17:27, 12 July 25Let's be serious, a floppy disk weighs almost nothing and doesn't spin hundreds or thousands of times per second. It doesn't need balancing.
#93
Quote from: XeNoMoRPH on 01:08, 11 July 25Memory bug is fixed, on the last DSK versión.I wonder who did this fix
.Thumbs up for Jörn!
@XeNoMoRPH Works like a charm now.
Out of couriosity, which mode do you prefer?
Stefan
#94
the lower voltage on the board is normal.. usually not quite that low..
but if its working..there is no problem!
there is a diag rom you can replace the onboard rom with.. but.. if ya seeing the basic screen.. its working fine!...so the diag isnt going to tell you much...
https://github.com/issalig/amstrad-diagnostics/blob/main/build/AmstradDiagLower.rom is the one you need to replace the onboard rom (you can use the upper rom version if you have a romboard,m4 etc)
but if its working..there is no problem!
there is a diag rom you can replace the onboard rom with.. but.. if ya seeing the basic screen.. its working fine!...so the diag isnt going to tell you much...
https://github.com/issalig/amstrad-diagnostics/blob/main/build/AmstradDiagLower.rom is the one you need to replace the onboard rom (you can use the upper rom version if you have a romboard,m4 etc)
#95
Hi
I am not so familiar with the Amstrad CPC and I am testing a very badly preserved 464, case was damaged by solvents and was in a very sorry state. I wasn't expecting much but when I powered it up I got the basic screen immediately. I've powered just the motherboard by jumpering 1 and 3 as the tape deck is in a bad shape and need servicing.
As said I got the blue and yellow basic screen however when checking voltage rails and signals, I noticed that the +5V was actually measuring +4.0V, CPC was connected to my bench PSU which was delivering a stable 0.750A on a setting of 5.02v@1.5A so there does not seem to be a short and current does not seem too high. I can't do too many tests until I reassemble everything chips temperatures seems fine, CPU and the video chip are hotter than others and the yamaha is slightly hot, while all others are cold to the touch. Caps are all ceramic, with only one electrolytic that does not seem damaged ... so, is this nominal?
Considering at the moment I have no way to load programs into the computer except typing them with the keyboard, is there any kind of diagnostic rom that will perform a more in depth check?
BR
I am not so familiar with the Amstrad CPC and I am testing a very badly preserved 464, case was damaged by solvents and was in a very sorry state. I wasn't expecting much but when I powered it up I got the basic screen immediately. I've powered just the motherboard by jumpering 1 and 3 as the tape deck is in a bad shape and need servicing.
As said I got the blue and yellow basic screen however when checking voltage rails and signals, I noticed that the +5V was actually measuring +4.0V, CPC was connected to my bench PSU which was delivering a stable 0.750A on a setting of 5.02v@1.5A so there does not seem to be a short and current does not seem too high. I can't do too many tests until I reassemble everything chips temperatures seems fine, CPU and the video chip are hotter than others and the yamaha is slightly hot, while all others are cold to the touch. Caps are all ceramic, with only one electrolytic that does not seem damaged ... so, is this nominal?
Considering at the moment I have no way to load programs into the computer except typing them with the keyboard, is there any kind of diagnostic rom that will perform a more in depth check?
BR
#96
Consequently, we can also replace : LD BC,#0000 :source_skip ;; Skip bytes in source data.
with
LD C,0 :source_skip
since the B' register will always be 0 after the loop, and the C' value will never be greater than 6.
with
LD C,0 :source_skip
since the B' register will always be 0 after the loop, and the C' value will never be greater than 6.
Code Select
ORG &AFC3
y_loop:
LD A,C
EXX
LD B,A ;;B'=x_loop counter
x_loop:
LD A,(DE) : INC DE ;; Load sprite data and update source pointer.
OR A : JR Z,$+3 ;; Is byte opaque?
LD (HL),A ;; Write byte.
INC HL ;; Update target pointer.
DJNZ x_loop
EX DE,HL ;; Swap registers to allow DE=DE+BC.
LD C,0 :source_skip ;; Skip bytes in source data.
ADD HL,BC
EX DE,HL
LD BC,#07FA :target_skip ;; Go to next row and skip bytes on screen.
ADD HL,BC
BIT 6,H ;; Was the screen memory left?
jump_condition: JP Z,$+7
LD BC,#C040 : ADD HL,BC ;; Then correct target pointer.
EXX
DJNZ y_loop #97
Thank you for the comments.
In the AFC3 loops, I think we can get rid of the following instructions:
EX AF,AF' ;; Restore A.
DEC A : JP NZ,x_loop
and use the register B' as a loop counter. The BC' register is overwritten just after, as we can see.
So the code would become :
I have not tested it yet.
In the AFC3 loops, I think we can get rid of the following instructions:
EX AF,AF' ;; Restore A.
DEC A : JP NZ,x_loop
and use the register B' as a loop counter. The BC' register is overwritten just after, as we can see.
So the code would become :
Code Select
ORG &AFC3
y_loop:
LD A,C
EXX
LD B,A ;;B'=x_loop counter
x_loop:
LD A,(DE) : INC DE ;; Load sprite data and update source pointer.
OR A : JR Z,$+3 ;; Is byte opaque?
LD (HL),A ;; Write byte.
INC HL ;; Update target pointer.
DJNZ x_loop
EX DE,HL ;; Swap registers to allow DE=DE+BC.
LD BC,#0000 :source_skip ;; Skip bytes in source data.
ADD HL,BC
EX DE,HL
LD BC,#07FA :target_skip ;; Go to next row and skip bytes on screen.
ADD HL,BC
BIT 6,H ;; Was the screen memory left?
jump_condition: JP Z,$+7
LD BC,#C040 : ADD HL,BC ;; Then correct target pointer.
EXX
DJNZ y_loopI have not tested it yet.
#98
General Discussion - Introductions / Re: New 3" disks? Floating an ...
Last post by eto - 13:33, 12 July 25Quote from: ZorrO on 12:55, 12 July 25very low margin? - I don't think so. There's about 2mm betweenI primarily meant that I would expect that the circle must be close to perfect to avoid being unbalanced and that the foil doesn't get any buckles when being cut.
But I might be wrong with that assumption.
#99
A
Amstrad CPC hardware / Re: Amstrad CPC cartridge and ...
Last post by arnoldemu - 13:25, 12 July 25There are problems:
- the cartridge doesn't have a write signal
- the cartridge doesn't have access to z80 signals for I/O
therefore very limited by communications with the cart and any communication operations would need to be done by reading from various rom addresses.
It may be possible to be creative and run a pi on the board and the software runs on the pi AND this pi has a video output.
What would be possible is to attach the PI to expansion of the Amstrad with the software on the cart but then this would not work on GX4000 but would work on CPC and Plus.
- the cartridge doesn't have a write signal
- the cartridge doesn't have access to z80 signals for I/O
therefore very limited by communications with the cart and any communication operations would need to be done by reading from various rom addresses.
It may be possible to be creative and run a pi on the board and the software runs on the pi AND this pi has a video output.
What would be possible is to attach the PI to expansion of the Amstrad with the software on the cart but then this would not work on GX4000 but would work on CPC and Plus.
#100
D
General Discussion - Introductions / Re: CPC 464 ral codes
Last post by deadmeat - 13:18, 12 July 25I've tried anthracite grey as the can was really cheap, actually result is not bad... it looks different (as clearly seen comparing two cases - above is the painted one) but much better than a discoloured original one. I may order a RAL 7020 if I find a good deal but for now will do. The bottom of the case instead is most definitely a 9004 signal black. It's just identical.