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#31
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Technical Support - Software related / Re: Optimize and/or trim CPR i...
Last post by andycadley - Yesterday at 22:07Quote from: eto on Yesterday at 21:44Off the top of my head, the GX and Plus treat Physical Page 3 differently: A Plus will page it in when ROM 7 is requested, a GX will not. So a small cartridge might only need a lower ROM (Physical page 0) and a second ROM that can be used to identify the model (Physical page 3).Quote from: andycadley on Yesterday at 16:36There's no requirement for cartridges to be linear (and there are potential advantages to them not being linear).
Do you have an example in mind? From what I know about physical cartridges and how they have been built I don't see how cartridges would not be linear or what advantages that could have.
More importantly, at the time the format was defined, nobody really knew what "real" GX cartridges might be like - so the format was defined to be flexible enough to cope with anything and extensible enough should the need arise (to avoid the problems with a myriad of other emulator "formats" that actually have multiple different specs to cope with weirdness that was discovered later).
#32
Technical Support - Software related / Re: Optimize and/or trim CPR i...
Last post by eto - Yesterday at 21:44Quote from: andycadley on Yesterday at 16:36There's no requirement for cartridges to be linear (and there are potential advantages to them not being linear).
Do you have an example in mind? From what I know about physical cartridges and how they have been built I don't see how cartridges would not be linear or what advantages that could have.
#33
Technical support - Hardware related / Re: USIfAC II, technical probl...
Last post by ikonsgr - Yesterday at 18:31AFAIK, there is only one type of network resistors, which is nothing more than a bunch of resistors having one side in common 
The actual code for the network needed is "A09-103": https://www.ebay.ie/sch/i.html?_nkw=A09-103+resistor&_sacat=0&_from=R40&_trksid=m570.l1313
You can also ask for it ,as: "9pin 10k network resistor" which is practically the same.
This type of resistors are used mainly as "pull-ups" (or "pull-down") usually on data bus or address bus, where, instead of having many resistors that connect each data/address bus bit with power supply, you use these "multi pin strings" and save both money and space ;-)
network resistors come in countless variations, depending on the resistor value and the number of resistors.
The actual code for the network needed is "A09-103": https://www.ebay.ie/sch/i.html?_nkw=A09-103+resistor&_sacat=0&_from=R40&_trksid=m570.l1313
You can also ask for it ,as: "9pin 10k network resistor" which is practically the same.
This type of resistors are used mainly as "pull-ups" (or "pull-down") usually on data bus or address bus, where, instead of having many resistors that connect each data/address bus bit with power supply, you use these "multi pin strings" and save both money and space ;-)
network resistors come in countless variations, depending on the resistor value and the number of resistors.
#35
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Technical Support - Software related / Re: Optimize and/or trim CPR i...
Last post by andycadley - Yesterday at 16:36There's no requirement for cartridges to be linear (and there are potential advantages to them not being linear). Furthermore, since it's based on RIFF, it's a lot easier to extend if people wanted to, say to include instructions or to support NES style "mapper" arrangements.
And the overhead of RIFF compared to a straight binary is minimal. Admittedly a lot of DSK->CPR conversions are probably massively bloated, but that's really the fault of the tools used to do the conversion rather than the CPR format, you'd still end up with a massively unnecessary file if they'd been writing raw binary.
And the overhead of RIFF compared to a straight binary is minimal. Admittedly a lot of DSK->CPR conversions are probably massively bloated, but that's really the fault of the tools used to do the conversion rather than the CPR format, you'd still end up with a massively unnecessary file if they'd been writing raw binary.
#36
Technical Support - Software related / Re: Optimize and/or trim CPR i...
Last post by eto - Yesterday at 15:52Compared to single 16K ROMs agreed.
But for cartridges what is the benefit of a CPR compared to simple, binary 128K, 256K or 512K ROM file? For what was the format established in the first place?
The only hypothetical benefit I see is that unused parts do not "waste" space on a hard drive. And this benefit is barely used as almost all CPRs I have ever seen are 512K CPRs even if the content is a lot less. Even if it would be used, on a typical 4GB SD Card, we still can put 8000 512K ROMs.
Or are there any potential future updates of the format?
Btw: where is the format defined? The one on e the Wiki is quite vague and the link to the original is dead.
But for cartridges what is the benefit of a CPR compared to simple, binary 128K, 256K or 512K ROM file? For what was the format established in the first place?
The only hypothetical benefit I see is that unused parts do not "waste" space on a hard drive. And this benefit is barely used as almost all CPRs I have ever seen are 512K CPRs even if the content is a lot less. Even if it would be used, on a typical 4GB SD Card, we still can put 8000 512K ROMs.
Or are there any potential future updates of the format?
Btw: where is the format defined? The one on e the Wiki is quite vague and the link to the original is dead.
#37
R
Technical support - Hardware related / Re: USIfAC II, technical probl...
Last post by RobertK - Yesterday at 15:41Quote from: ikonsgr on 18:25, 05 June 25That's great news, I will try that!Quote from: RobertK on 10:16, 03 June 25There is only the small issue that with my particular CPC model I need to press the ULIfAC's reset button every time after powering up (cold-booting) the CPC, but I can live with that. According to John, this is "normal" behaviour for older 464 models from 1984.Just add a pullup resistor network on Amstrad's data bus and most probable this problem will be fixed too.
Just a dumb question: I have seen that there are "Parallel Connection" and "Star Connection" resistor networks available. Which type is supposed to be used here?
#38
Technical Support - Software related / Re: Optimize and/or trim CPR i...
Last post by roudoudou - Yesterday at 15:37Quote from: GUNHED on Yesterday at 13:28Well, I never understood why to use CPRs instead of ROMs directly. A CPR file has no advantage (or has it one?), but just fills in some bytes for no gain. What do you think?
Suggesting to move to read ROM content in general!
Advantage, you can gainz some bytes on a 16 cores / 64Gb RAM machine with 32TB HDD ...
#39
I have now fixed and re-checked all comparator pins, they are all fine now. I have been able to do this without having to remove the capacitors. However, the CPC image was still black after that.
So I soldered each THT hole from above and filled solder into each hole. People in another forum wrote that they had the same problem when the hole wasn't entirely "filled". I don't know what's special about this PCB, because there is definitely a via on each hole.
Anyway, after that there was some progress. At least I am now seeing something:
The bright green lines are text lines that are not displayed properly (and they are vertically a little off towards the bottom). When I type something, I see a new line appearing.
Any hints what could be missing when the picture looks like this?
So I soldered each THT hole from above and filled solder into each hole. People in another forum wrote that they had the same problem when the hole wasn't entirely "filled". I don't know what's special about this PCB, because there is definitely a via on each hole.
Anyway, after that there was some progress. At least I am now seeing something:
The bright green lines are text lines that are not displayed properly (and they are vertically a little off towards the bottom). When I type something, I see a new line appearing.
Any hints what could be missing when the picture looks like this?
#40
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Technical Support - Software related / Re: Optimize and/or trim CPR i...
Last post by andycadley - Yesterday at 15:21And CPR contains information about how the ROMs need to fit into slots, which pure binary ROMs require the user to understand.