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#1
#2
G
Technical support - Hardware related / Re: 664 Keyboard issue
Last post by glynharper - Today at 01:04Quote from: McArti0 on 08:09, 03 August 25I posted the pictures for you. Any thoughts on what it could be?Quote from: McArti0 on 19:40, 02 August 25show us what appears when you press only 7, only 8 and only 9
Can You add big resolution photo of mainboard?
Thanks.
#3
I went to the event, it was great!
The SymbOS stand was very well located, impossible to miss it.
According to the booklet, there was also an Amstrad CPC 464 portable exhibited - I did not see it though.
Talking about vintage, there was also a demo of the IBM 1401 computer at the CHM downstairs, really amazing.
The SymbOS stand was very well located, impossible to miss it.
According to the booklet, there was also an Amstrad CPC 464 portable exhibited - I did not see it though.
Talking about vintage, there was also a demo of the IBM 1401 computer at the CHM downstairs, really amazing.
#4
Quote from: Bread80 on Yesterday at 22:13I'm not sure what the "pelrun recreation" refers to. Is that the redrawn '464 schematic on this website?No, it's the 6128 schematic I drew up in kicad a few years back: https://github.com/pelrun/cpc-schematics
#5
Quote from: orzel on Yesterday at 16:54Ok. Good to know !I'm not sure what the "pelrun recreation" refers to. Is that the redrawn '464 schematic on this website?
While I'm it, I have a few other questions, all about the 'official' schematics.
1) There's r154, pull-up on /iorq (near z80). It doesn't appear in pelrun recreation, and I dont seem to have it in my CPC. There's a cryptic comment about HS-CMOS -> USE. Any idea what this means ? I suppose it's only needed in some (old?) cases ?
2) The 6845 output "ma11" is connected to "PAD". Which doesn't appear anywhere else. Any idea what that is ? Funnily, on perlun pcb, this pad is routed toward... a dead end. So clearly Amstrad intended to do something about it.. ? (or did ?)
3) Near the a15 pin on gatearray, it's written /nysync. Any idea what that is ?
anyone knows what
1. Unconnected input on LS series logic will float into a high state. The same on CMOS (HC and HCT series in this time period) will fluctuate and cause issues and even damage to the chip. The pull-up is to stop the signal from floating.
Why does this matter? Because the /BUSRQ input on the Z80 will cause it to tristate most of it's output (and bidirectional) pins. (This is to allow a peripheral device to access memory and/or other I/O devices). I'm not sure any hardware ever did that on the CPC but it needs to be prepared for.
If you look at the '464 schematics you'll see that the GA actually has these pull-ups internally on /MREQ, /IORQ, /RD and /WR, as well as on it's open collector output signals - thus saving Sir Alan a few bob in components. I'm not sure why they felt the need for an additional pull-up on the CMOS models. It's probably down to the analogue properties of component pins or, maybe, stricter timing requirements (HC and HCT tend to be a little slower than LS).
2. I've always assumed this is a test pad. Ie. something used during burn-in tests to check the 6845 is functioning properly.
3. I have absolutely no idea, and I can't think what it might stand for. Maybe Lord Sugar's boy band?
#6
Amstrad CPC hardware / Re: Dandanator Mini Dual ROM G...
Last post by MiguelSky - Yesterday at 20:46Hii, it's weird that no one has uploaded this previous version. But I tried to start it today and it seems JavaFx it's not supporter by Java anymore. I'm looking for a solution for this...
#7
Wait until you see the final battle 
#8
Amstrad CPC hardware / Re: Dandanator Mini Dual ROM G...
Last post by salvogendut - Yesterday at 19:56Guys I have the same problem, any kind soul willing to share the jar file? Please send me a pm @joky @Wobble_master ?
#9
Quote from: Jean-Marie on Yesterday at 08:52Don't miss the Game Over music : it's epic !The funeral is very grand, yes. ahahah
#10
Ok. Good to know ! 
While I'm it, I have a few other questions, all about the 'official' schematics.
1) There's r154, pull-up on /iorq (near z80). It doesn't appear in pelrun recreation, and I dont seem to have it in my CPC. There's a cryptic comment about HS-CMOS -> USE. Any idea what this means ? I suppose it's only needed in some (old?) cases ?
2) The 6845 output "ma11" is connected to "PAD". Which doesn't appear anywhere else. Any idea what that is ? Funnily, on perlun pcb, this pad is routed toward... a dead end. So clearly Amstrad intended to do something about it.. ? (or did ?)
3) Near the a15 pin on gatearray, it's written /nysync. Any idea what that is ?
anyone knows what
While I'm it, I have a few other questions, all about the 'official' schematics.
1) There's r154, pull-up on /iorq (near z80). It doesn't appear in pelrun recreation, and I dont seem to have it in my CPC. There's a cryptic comment about HS-CMOS -> USE. Any idea what this means ? I suppose it's only needed in some (old?) cases ?
2) The 6845 output "ma11" is connected to "PAD". Which doesn't appear anywhere else. Any idea what that is ? Funnily, on perlun pcb, this pad is routed toward... a dead end. So clearly Amstrad intended to do something about it.. ? (or did ?)
3) Near the a15 pin on gatearray, it's written /nysync. Any idea what that is ?
anyone knows what