Re: Please help me identify this old EGA card

Posted on 2024-02-07, 20:26

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

MSxyz wrote on 2024-02-07, 17:12: I was expecting to see a 28.6Mhz crystal for CGA emulation... This one is easy: The ISA bus carries a 14.318MHz clock signal. No need for a crystal on the card. The IBM CGA had no crystal on the card at all.

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Re: Biostar MB-8433UUD-A

Posted on 2024-02-03, 18:16

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I blamed it on the FSB-to-PCI multiplier settings. But changing that to 1:2/3 didn't solve it. My personal experience is that the 1:2/3 divider is sometimes causing extra issues. I had setups that worked at 40MHz 1:1, but failed at 1:2/3 if I remeber correctly. 1:2/3 generates an asymmetric clock …

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Re: Biostar MB-8433UUD-A

Posted on 2024-02-03, 18:11

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Did you decide to shelf the 8433UUD cache interposer project? There were some 8 ns TSOP and SOJ modules from ISSI. I show a photo of the top/bottoms here: https://www.vogons.org/viewtopic.php?p=1231100#p1231100 As they are from China, I don't know if they are authentic or not. The ISSI TSOPs work …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-02-03, 18:02

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by mkarcher

in PC Emulation

in PC Emulation

The main issue is when "blanking end" after "retrace end" horizontally (as well as retrace usually) it's on the next scanline? So when the horizontal retrace and blanking ends, before the start of the next video memory being rendered (until horizontal total and after that the horizontal display …

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Re: EGA/VGA and mode Fh mono 'colors'?

Posted on 2024-02-03, 15:35

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by mkarcher

in PC Emulation

in PC Emulation

As far as I understand mode F, it's a standard 16-color EGA mode. 32 bits from video-memory get transformed into 8 pixels of 4 bits each (sent to the AC) when then drives 6 pins in the monitor socket, which would enable EGA monitors to display 64 different colors (but EGA monitors can not …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-02-03, 12:58

by

by mkarcher

in PC Emulation

in PC Emulation

So copper bars don't render on overscan? Even though overscan is through the DAC? So effects from the DAC will work strangely (wrong scanline) for the left half of screen's overscan if overscan color is set to DAC entry #0 on VGA? Because display is still disabled there? That's either the remainder …

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Re: Biostar MB-8433UUD-A

Posted on 2024-02-03, 12:57

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Also increased the level 2 cache from 256kb to 512kb yesterday. Didn't see much of a speed increase from 15ns to 10ns but need to do some more testing. Anybody knows a good test program (besides cachechk) to test it? My experience is that running these tests usually indicates bad L2 cache timings …

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Re: Trident TGUI9440 memory upgrades

Posted on 2024-02-03, 09:44

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is it possible to stack 256Kx4 DIP20 to make 256Kx8 DIP24? Yeah, that should work perfectly fine. Connect all pins except the data pins (address, /RAS, /CAS, /WE) on both chips. Then just use the 8 data bits provided by the 2 chips as the 8 data bits for the x8 chips. I didn't check pinouts, but …

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Re: Vesa Local Bus graphics card - upgrade video memory

Posted on 2024-02-03, 09:38

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Not sure why people expect video ram to increase performance. It's just frame buffer which only gives you higher resolutions/bit depths. Unless the chipset does memory interleaving of some kind to effectively widen the bus. I only know a handful of chipset families that do this. Video memory size …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-02-03, 07:28

by

by mkarcher

in PC Emulation

in PC Emulation

What I mean with the copper bars is does blanking affect the display enable signal in any way (input status 1 register's bit 0)? The display enable signal is true (i.e. bit 0 is clear) if the current character counter is smaller than or equal to the horizontal display end value, and the current …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-02-02, 22:27

by

by mkarcher

in PC Emulation

in PC Emulation

So then what effect does the polarities actually have on the CRT signal? Does the monitor ignore blanking (like cutting it off the image by disabling the beam (done anyways) and deflection to stay at the left border)? What about horizontal scanline moving effects like the copper demo? Won't that …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-02-01, 22:31

by

by mkarcher

in PC Emulation

in PC Emulation

If HSYNC=31.5kHz and VSYNC=60Hz, then it must be the 480-line mode - no need to look at the SYNC polarity, it's enough to measure the frequencies. Before monitors had control processors (i.e. up around to 35kHz HSYNC), measuring the sync frequency was more involved than looking at the SYNC polarity …

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Re: Can I get sound and midi from the same soundblasters card in DOS?

Posted on 2024-02-01, 21:22

by

by mkarcher

in Marvin \ Sound

in Marvin \ Sound

To expand on this, I think the game was asking what card you might have so it new what port to try to play midi out of. In my case the soundblaster 16 ports worked to get the sound through my audio card. Yes, that definitely works. You will get the kind of music most players heard in the 90s, …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-02-01, 21:18

by

by mkarcher

in PC Emulation

in PC Emulation

So basically it adjusts the horizontal retrace's vertical distance to fill that size (including blanking areas)? Yeah, that's a valid way to look at it. Because software can decide to give more or less horizontal retraces in a frame? You should be aware that the total line count in a 350-line frame …

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Re: Can I get sound and midi from the same soundblasters card in DOS?

Posted on 2024-02-01, 06:47

by

by mkarcher

in Marvin \ Sound

in Marvin \ Sound

Hello and thank you for the help. I was hoping it was a generic enough issue for a generic answer so i wouldn't have to get the tools out and get the sound card. Specifically I have a Soundblaster CT4170, and specifically this game I'm trying to play at the moment is DnD Blood and Magic. It looks …

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Re: Purpose of negative horizontal sync polarity on EGA(/(S)VGA) cards?

Posted on 2024-01-31, 22:39

by

by mkarcher

in PC Emulation

in PC Emulation

Also, what effect does the VGA hsync/vsync polarity really have on a CRT? Does it change something in the monitor? The VGA monitor runs at a fixed frequency of 31.5kHz horizontal, but can operate at 350 visible lines, 400 visible lines or 480 visible lines. Standard VGA monitors typically decode …

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Re: Emerson 500EC IDE issue explination and solution.

Posted on 2024-01-31, 06:38

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I might be interested, do you have any theory as to why they flipped the data bits ? Most likely easier trace routing, but it could have been a mistake, Look at the ISA slot pin assignment: The data bits D0-D7 are layed out with the most significant bit towards the bracket. The data bits D8-D15 are …

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Re: FIX: Riva TNT / TNT2 graphics cards, Windows 3.1(1) and PCI IRQ sharing

Posted on 2024-01-29, 21:57

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

Trying to find some further driver affected by this bug, I downloaded Detonator v2.08 from the VOGONs driver library. While it still contains a slightly different machine encoding of the broken code, it contains a second layer of setting the carry flag correctly before returning from the IRQ handler …

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Re: Some questions regarding the 8088 platform..

Posted on 2024-01-29, 19:54

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Nope. In fact behaviour with one installed can be downright weird. I was troubleshooting a card that stopped an XT system from booting (probably a resource conflict, but could also be a dead 74-logic chip somewhere) and decided to stick my (16b ISA) POST card in on the off chance it told me …

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Re: Chinon FZ-506 rev.A trying to get this to variable Speed (300kb/s)

Posted on 2024-01-29, 19:39

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

For standard PC use, you need to keep the convention that pin 2 high means HD operation and pin 2 low means DD operation. So the dual-speed option that is at least partially PC compatible is the first(!) row of the manual, not the second one. If you configure the drive to dual-speed operation and …

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