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JackAsser
Registered: Jun 2002
Posts: 2014 |
Detect C128 in C64-mode without exploiting 2mhz mode?
Reason: Easyflash emulation in 1541u2 doesn’t work in 2mhz mode. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: Indeed. And for more fun, its not exactly random, but depends on what the VIC fetched in the previous cycle :)
True. I'll change that to vdcProbablyPresent and then read/write some into VDC RAM to be sure (with timeout on the polls). |
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Oswald
Registered: Apr 2002
Posts: 5095 |
why not just test at $d030, you set some used bit, and then test it if it stays the same for the entire next frame, then clear the bit and same. |
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Krill
Registered: Apr 2002
Posts: 2981 |
Quoting Oswaldwhy not just test at $d030 $D030 is implemented by a couple of accelerators as well, so its presence doesn't say anything about the machine being a C-128.
Besides, see OP: "Easyflash emulation in 1541u2 doesn’t work in 2mhz mode." |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: Quoting Oswaldwhy not just test at $d030 $D030 is implemented by a couple of accelerators as well, so its presence doesn't say anything about the machine being a C-128.
Besides, see OP: "Easyflash emulation in 1541u2 doesn’t work in 2mhz mode."
For this particular problem I just want to detect the VDC chip. It has nothing to do with CPU speed. It's for dual-screen support in Eye of the Beholder. The map rendering on the VDC is almost completed now. |
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Krill
Registered: Apr 2002
Posts: 2981 |
Quoting JackAsserFor this particular problem I just want to detect the VDC chip. It has nothing to do with CPU speed. A VDC is present if and only if the machine is a C-128, no? =) (Or do VDC-less C-128s exist? :-O) |
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chatGPZ
Registered: Dec 2001
Posts: 11387 |
But what if i put a VDC in my C64? |
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Oswald
Registered: Apr 2002
Posts: 5095 |
Quote: But what if i put a VDC in my C64?
that points to autodetect then let the user change, then save settings not.to bother.him again. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: Quoting JackAsserFor this particular problem I just want to detect the VDC chip. It has nothing to do with CPU speed. A VDC is present if and only if the machine is a C-128, no? =) (Or do VDC-less C-128s exist? :-O)
I mean, it's easier to detect the VDC than accidently detect a C128 and assume the VDC is there which will corrupt SID. |
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tlr
Registered: Sep 2003
Posts: 1790 |
Quote: I mean, it's easier to detect the VDC than accidently detect a C128 and assume the VDC is there which will corrupt SID.
If the purpose is to use the VDC and your code doesn't care about other C128 features, then it makes total sense to detect just the VDC directly. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: If the purpose is to use the VDC and your code doesn't care about other C128 features, then it makes total sense to detect just the VDC directly.
My thought as well. I will not auto-enable the 2Mhz-mode in the presence of a C128 since the EF3-emulation on U2+ doesn't support that. I however do want to automatically detect the VDC. Enable the second screen with a menu config is just poor UX. Also it's not like there will be random chips in the D600-range. It's either a SID-chip, broken SID-chip, a VDC, a broken VDC or nothing. |
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