Re: Extracting MIDI from an old game

Posted on 2016-03-19, 09:34

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi guys, long time no see :cool: I know there was talk about this somewhere around here, but as I was not really around for a while, I forgot where things are. What I'd like to do is to extract and remaster the midi files from an old game, Knights of Xentar. Does any one have an idea how to do this …

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Re: VGA monochrome monitor (to use mode 7h when booting) detection?

Posted on 2016-03-19, 00:04

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by Jepael

in PC Emulation

in PC Emulation

Original IBM did not have any monitor ID bits, so it just takes a look if all RGB wires have enough load (monitor connected) or if there is not enough load (only one channel used for monochrome monitor). That monitor sense is available by reading 0x3c2 bit 4.

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Re: Creative CT1300B operation

Posted on 2016-03-17, 20:12

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by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't think the card needs -5V for anything. Or -12V. The digital logic should just use +5V. The TEA2025B is a single supply speaker amplifier, and it works fine with +12V. The CMS chip output needs filtered +5V, but that's made with el cheapo 5.1V zener shunt regulator from +12V. Man, that is a …

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Re: Missing SMD capacitor on 3dfx Voodoo 5 5500 PCI

Posted on 2016-03-17, 20:03

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes it's definitely the bypass cap for the SC1102 voltage regulator IC supply voltage, it's 5V straight from the PCI bus. But, since the datasheet says it needs 100nF cap, and there's definitely two different caps on the card, it is hard to say if there is a 100nF and a 1uF, or a 100nF and a 10nF, …

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Re: Creative CT1300B operation

Posted on 2016-03-16, 20:22

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by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Do you have anything else that could exist at port 220h? If the CMS chips are socketed, they could have bad contacts between socket and the chip, so try to push it a little bit back in the socket. On some Sound Blasters, if the CMS chips were not installed, reportedly, accessing them caused the …

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Re: Can anyone help me fix my VGA monochrome(mode 7) emulation?

Posted on 2016-03-16, 20:18

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by Jepael

in PC Emulation

in PC Emulation

What VGA BIOS are you using? Maybe it does not support mode 7h properly, or, maybe it sets just some registers correctly and it is enough for that VGA hardware (physical or emulated). Why it works differently with "MODE MONO" command, it could be that after that the VGA BIOS either tries to actually …

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Re: Best way to identify a floppy's capacity

Posted on 2016-03-15, 15:31

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

https://en.wikipedia.org/wiki/Floppy_disk#3.C … nch_floppy_disk If it has the HD hole, it is 1440KB floppy. If it only has write protect slider hole, it is 720KB floppy.

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Re: VGA Mode 7h difference with mode 0-3h?

Posted on 2016-03-14, 18:52

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by Jepael

in PC Emulation

in PC Emulation

VGA Underline register sets on which character line the underlining would be if a character is underlined. In some documentations it is said it only works in monochrome emulation mode. The underline attribute bit selects if the character in question is underlined or not. MDA has no bolding.

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Re: VGA Mode 7h difference with mode 0-3h?

Posted on 2016-03-14, 18:23

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by Jepael

in PC Emulation

in PC Emulation

If the bit is zero, text attributes are in color adapter mode (CGA,EGA,VGA text modes), the attribute byte defines character foreground/background/blinking. There is no underlining, or inverse video attributes. If the bit is one, text attributes are in mono adapter mode (MDA text mode), the …

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Re: Teach me some electronics repair skills.

Posted on 2016-03-14, 16:51

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Okay, so take two: The "rated output" is +12V 0.5A+5V 2A-12V 0.1A-5V 0.1A So, um...which is it? Is it all of them? Or does it depend on special kinds of cables? It lists the maximum current for each voltage. But, that sounds pretty low. I understand this is for an 8086 computer, but if you count …

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Re: VGA Mode 7h difference with mode 0-3h?

Posted on 2016-03-14, 16:20

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by Jepael

in PC Emulation

in PC Emulation

The mode 7h does not just set palette to monochrome, it also makes the attribute byte not to indicate foreground/background colors but blinking, underlining and high intensity instead to be MDA compatible. AFAIK, whether VGA is made to emulate CGA or MDA attributes, the information is found in …

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Re: Teach me some electronics repair skills.

Posted on 2016-03-14, 15:54

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Okay. So. As an example: my new 8086 I got has a mains supply rating of "100-240V ~ 2.1A" Therefore, with Ohms law, that's 2.1A x 240V = 504W. Is that right? Not in this case. Because it works at anything between 100VAC and 240VAC, it is a switching power supply. The 2.1A is the maximum rated …

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Re: DB60XG / XR385 repair and modification

Posted on 2016-03-13, 19:51

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by Jepael

in Milliways

in Milliways

Yes, it is. I think so. Thank you! Now I'll check DB50 and SW60 about 4/8FS SEL to see its connecting to ground (or not). And then will think how to connect DIT4096. If DIT4096 needs Master Clock Signal it is necessary to find it on XQ036AO chip. Looking at DB50XG pictures, it's not connected to …

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Re: dumping VGA BIOS: help needed

Posted on 2016-03-13, 12:58

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Why the need of separate EEPROM programmer to dump the contents? Why not just put the card in a PC, and read the video BIOS contents while it is in the PC and just write it into a file?

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Re: DB60XG / XR385 repair and modification

Posted on 2016-03-08, 18:43

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by Jepael

in Milliways

in Milliways

I reviewed XR385, DB50XG, SW60XG boards and found that on XR385 there is AK4510 DAC (and on MU10 also) but on DB50/SW60 there is another DAC NEC D63200. Here are datasheets: http://www.ym2149.com/mu10_spdif/ak4510.pdf http://www.alldatasheet.com/datasheet-pdf/pdf/92412/NEC/UPD63200.html? - …

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Re: PIT emulation gives incorrect results with 8088 MPH's credits?

Posted on 2016-03-07, 19:28

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by Jepael

in PC Emulation

in PC Emulation

No, it does not use IRQ2. CGA does not have it. Besides the video timing is wildly different, using default CGA mode on real CGA adapter draws ~15700 lines per second at ~59.92 frames per second, while emulated CGA mode on VGA adapter draws ~31469 lines per second at ~70.09 frames per second. And …

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Re: PIT emulation gives incorrect results with 8088 MPH's credits?

Posted on 2016-03-06, 22:20

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by Jepael

in PC Emulation

in PC Emulation

Why from 0 to 65535? The previous signal would be (as given by the PC Speaker) -32768, the new sample +32767, so the output should move as a result from the high pass filter (previous was zero) to 32767, not 65536? Unless you would double the amplitude from the PC Speaker itself(which isn't done)? …

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Re: 8086 average clocks per instruction (when running normally)?

Posted on 2016-03-06, 21:34

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by Jepael

in PC Emulation

in PC Emulation

Of course a perfectly written CPU manual is the absolute truth for the CPU. But only for the CPU. From what you say in your first point, it appears you think cycle accurate means only the CPU. To me and many others, cycle accurate emulation means the whole computer system (PC, arcade cabinet, …

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Re: PIT emulation gives incorrect results with 8088 MPH's credits?

Posted on 2016-03-06, 20:48

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by Jepael

in PC Emulation

in PC Emulation

Emmm. Jumping up and down by 64K still fits inside 16-bits? signed 16-bits? Yes if you don't remove DC and start from -32768. No if you remove DC and start from 0. Also, the filter only attenuates(lowers volume), not amplifies it? Yes, there is attenuation of low frequencies, yes, it does not …

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Re: PIT emulation gives incorrect results with 8088 MPH's credits?

Posted on 2016-03-05, 20:45

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by Jepael

in PC Emulation

in PC Emulation

You could try the filters separately if you wanted, like read a wav file and filter it and write output to another wav file. But I think I figured out at least one thing that could cause the problems you see. You convert the PIT output of 0s and 1s blindly to full scale -32768 and +32767 without …

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