Re: VGA custom resolution

Posted on 2020-09-28, 10:03

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

One issue that is often overlooked is that different modes might need different pixel clocks. VGA has 25.175 MHz, only, but higher resolutions typically need a higher frequency to keep the refresh rate acceptable. PLL-based designs will typically be more flexible than SVGA cards with separate …

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MCGA monitor at 15 KHz?

Posted on 2020-09-28, 07:34

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

I wonder what type of monitor is in that IBM which 8-bit guy ended up trying to boot. He says it's MCGA, so the monitor should be VGA, but I'm clearly seeing 15 KHz... MCGA is able to drive CGA frequencies. How do I know? I tried a IBM PS/2 model 30 with a non-IBM VGA monitor, which obviously did …

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Re: VGA custom resolution

Posted on 2020-09-28, 07:27

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

EDIT: Another unrelated question here; can SVGA support custom resolutions? If you are talking about custom resolution already supported by the VGA card: Yes, most later SVGA cards also support them, because VGA compatibility was of high importance at that time for the general audience. Graphics …

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Re: Troubleshooting Hercules Dynamite VLB card (Tseng ET4000)

Posted on 2020-09-28, 07:19

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by mkarcher

in Marvin \ Video

in Marvin \ Video

It's difficult to find out whether the problem is caused on the analog or the digital side, because the analog signal is sampled by the monitor and displayed in a digital way. If you happen to have a good CRT at hand, the picture on the CRT might help finding out whether the problem is analog or …

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Re: Troubleshooting Hercules Dynamite VLB card (Tseng ET4000)

Posted on 2020-09-27, 21:46

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Wow, that looks like the effect I expect to obtain if I flip on the "256 color mode" bit in the Attribute Controller while in text mode. It would turn a monochrome 8x16 character cell into a 4-color 4x16 color cell. If the problem is that the 256-color mode enable bit is stuck, it would be a defect …

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Re: Yet Another PSU Went Pop Thread (NOS edition)

Posted on 2020-09-27, 21:35

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The toast component is a through-hole ceramic "disc capacitor," right? What does this part usually do in a PSU where it is positioned? I have some knowledge and experience with power supplies, and if I am correct, that capacitor is part of the snubber network in the primary side. The job of the …

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Re: S3 ViRGE VLB project (or " Making a Concurrent for Creative 3D Blaster VLB" )

Posted on 2020-09-26, 22:57

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Which art of disassembler do you use? IDA ? I have here Virge Driver for Win95, can you look quick ? That driver is PCI only, according to the INF file. The driver does not seem to read the bus type from the chip, and blindly assumes PCI. It enables the "new MMIO only" mode, whereas the Trio …

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Re: VGA custom resolution

Posted on 2020-09-26, 21:20

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

However, technically, nothing speaks against using a 320x200 mode with the timings of a 320x240 mode, i.e. with square pixels and letterboxing. Except for the refresh rate of 60Hz. It causes noticable flicker on a lot of VGA (or Super-VGA) CRT monitors. But you are right that this mode is perfectly …

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Re: S3 ViRGE VLB project (or " Making a Concurrent for Creative 3D Blaster VLB" )

Posted on 2020-09-26, 10:19

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by mkarcher

in Marvin \ Video

in Marvin \ Video

I found also S3 Driver for Trio64V+ VLB on my floppy disc. I don't know, where have i it. Their INF file show me: no difference between PCI and VLB, both got same driver. Trio64V+ has chip-marking: 86C765 Interessing notice: Trio64 and Trio64V+ has same PCI Vendor & Device ID, difference is only …

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Re: VGA custom resolution

Posted on 2020-09-26, 06:47

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by mkarcher

in Marvin \ Video

in Marvin \ Video

I have been thinking of making a game for DOS. I want to use VGA so I went through the resolutions. "Narrow" modes such as 256×224 tend to preserve the same pixel ratio as in e.g. 320×240 mode unless the monitor is adjusted to stretch the image out to fill the screen, as they are derived simply by …

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Re: Can someone help me make sense of this BIOS dump?

Posted on 2020-09-26, 06:34

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

hmm are the 8042 and mc146818 connected at all? I need to pull up an ibm pc/at tech reference No, they are not connected (except for the 8 data lines on the same bus, of course). But the reset logic in the BIOS kind-of connects them in software. The KBC knows whether the machine was reset "hard" …

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Re: Sound Bank rom dumps - how are made?

Posted on 2020-09-25, 18:16

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

OK, but in my case how I can ID what type of EPROM are those "Yamaha" branded chips - I mean the programmer and the adapter are probably dependent on the exact type - which pins are data, which are power supply pins, etc? I guess they are not EPROMs that you can "E"rase and "P"rogram, but plain old …

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Re: Hi! I just bought a luckystar ls486e rev c1 sis496/497 motherboard. I have some questions about it. Thanks

Posted on 2020-09-25, 17:03

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

renejr902 wrote on 2020-09-25, 16:30: Thanks for let me know. Only the 5 solder points at CN5 could be for ps/2. But it seems they go at the Winbond chip, if its true its not good. 😀 If they go to a a Winbond chip, my guess would be IrDA. Double so if the BIOS setup allows COM2 to be configured …

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Re: OPTi / Orchid Local Bus variants

Posted on 2020-09-25, 16:37

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm sure your board isn't that noname :) Can you show me its post screen and/or a bios dump ? :) I'm at the moment not near the board, but I can quote you the bottom line of the AMI BIOS (colored setup) POST screen: 40-0505-001432-00101111-070791-SIS_486C-F The line below "ROM BIOS (C)1990 American …

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Re: Hi! I just bought a luckystar ls486e rev c1 sis496/497 motherboard. I have some questions about it. Thanks

Posted on 2020-09-25, 14:53

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I just think about it. Did you try to get the PS/2 mice working with the J2 4pins on your luckystar ls486e motherboard. If you use ps2suppc.com before cutemouse driver, you dont have to mod your bios to support ps/2. If you decide to try it let me know if its work. Otherwise i will try it in a few …

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Re: OPTi / Orchid Local Bus variants

Posted on 2020-09-25, 10:23

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is this any good? Yes. Very good pictures. Your card does not need BS16# on pin D4. Do you happen to have any brand/model name for your card? Your card contains 74HC374 latch chips that are needed to assemble the results of multiple 16-bit read cycles from the ET4000AX chip into a single 32-bit …

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Re: Help me identify a 286 board

Posted on 2020-09-25, 10:14

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

@mrkarcher which opti board ? this might be a neat feature for UH19 ? "PAL dumps" :) It's the no-name Taiwaneese OPTi Local Bus graphics card I mentioned over here: https://www.vogons.org/viewtopic.php?f=46&t=76654 . @mkarcher - what are you using to read PALs? I have the TL866 but apparently it …

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Re: Hi! I just bought a luckystar ls486e rev c1 sis496/497 motherboard. I have some questions about it. Thanks

Posted on 2020-09-25, 10:04

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

3. I read that older bios of the motherboard dont support more than 2.1gb but more recent bios support larger disk than 2.1gb. Right now i have a 4.3gb, a 12gb, a 20gb with 2.1gb limit jumper and 40gb and 60gb. Could i get this board working with any of them ? and tell me please if this 2.1gb limit …

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Re: S3 ViRGE VLB project (or " Making a Concurrent for Creative 3D Blaster VLB" )

Posted on 2020-09-25, 09:47

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

Register is asserted over I/O Addresse or "old MMIO" at Axxxx Memory address range. As you said. "New" MMIO use 16MB (= A24) range for register-access, but register range is only 64kb width. By PCI card, you can added this address range (register & video memory) with offset, Video ROM doing this …

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Re: S3 ViRGE VLB project (or " Making a Concurrent for Creative 3D Blaster VLB" )

Posted on 2020-09-24, 17:36

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

It is not a good idea to have the video card respond to physical addresses 16MB-32MB, as this conflicts with RAM on better 486 systems. Possibly SAUP2 is indeed used to access the "16-32MB range", not as physical address, but inside the memory space of the card (which can be relocated using PCI …

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