Re: early matrox card comparison (features/performance)

Posted on 2022-01-25, 19:47

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Millenium is a great card for NT4/95/98, blazing fast 2D acceleration and capable of very high pixel clocks, so it's a good match for a higher end CRT that can handle high hsync frequencies. (I really enjoy running 800x600 at 120hz refresh rate, it makes everything feel so so SMOOTH...) Not so great …

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Re: Old CGA monochrome monitor color fidelity

Posted on 2022-01-24, 20:27

by

by kdr

in Marvin \ Video

in Marvin \ Video

Many of the turbo XT clones had graphics adapters that did both MDA and CGA modes, and were equipped with monochrome displays that could switch between the MDA and CGA frequencies, so you'd get a nice crisp MDA style text mode at the DOS prompt and normal CGA graphics (320x200 with 4 levels of mono …

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Re: Old CGA monochrome monitor color fidelity

Posted on 2022-01-18, 19:21

by

by kdr

in Marvin \ Video

in Marvin \ Video

Here's one of the few photos I have left of my monitor, albeit without a color test that shows any other shades unfortunately. That photo clearly shows an MDA/Hercules text mode (9x14 font) so I'm guessing that you had a Hercules (or compatible) mono card and used a TSR such as SIMCGA. You get two …

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Re: Help me identify this 8088 motherboard

Posted on 2022-01-11, 04:01

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I was surprised to see a Yamaha chip on the board! A quick search reveals that the Yamaha V6363 was a CGA/MDA/Hercules chip. How interesting...

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Re: CRT nostalgia vs the 15KHz monitor whine

Posted on 2022-01-07, 20:49

by

by kdr

in Milliways

in Milliways

Back when CRT televisions were still common, I could usually hear the 15.7khz whine even from another room. But most people couldn't hear it, even when I'd specifically point it out. (I can't hear the 18.4khz from a monochrome display, though.) And once a CRT is up and running, the whine will fade …

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Re: I recently found this hardware, AKA the Dumpster find thread.

Posted on 2021-12-28, 01:17

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here's a great resource for the M24: http://olivettim24.hadesnet.org/index.html You can build a keyboard adapter and also hook up a VGA monitor with another adapter (the M24 uses analog signals), provided your VGA monitor can sync to 25.9 KHz horizontal refresh rate (which unfortunately many …

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Re: I recently found this hardware, AKA the Dumpster find thread.

Posted on 2021-12-27, 05:10

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here's a literal "found it in a rubbish heap" entry from today: IMG_20211227_174626_t.jpg Reeks of cat piss and in terrible shape, it's an Olivetti M24! Quite vintage, apparently features an 8086 CPU inside. IMG_20211227_174645_t.jpg IMG_20211227_174651_t.jpg IMG_20211227_174837_t.jpg Proprietary …

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Re: EGA DOS benchmarks?

Posted on 2021-12-24, 20:57

by

by kdr

in Marvin \ Video

in Marvin \ Video

So far the only objective benchmarks suggested are the video tests from Check It and Landmark, which seem oriented towards text mode performance. Any others out there? I don't think EGA 4bpp has to be any slower than CGA 2bpp, because one of the big features of EGA graphics is the capability to …

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Re: IBM 5151 on modern PC

Posted on 2021-12-18, 03:32

by

by kdr

in Marvin \ Video

in Marvin \ Video

As far as destroying the horizontal output transistor goes, my impression is that *running the sync frequency too low* is what kills it. The lower frequency results in the H.O.T. being switched on for too long. Once the horizontal yoke and tuning inductors become fully saturated they essentially …

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Re: Question about 320 x 200 resolution with proper scanlines (not doubled!)

Posted on 2021-12-16, 20:35

by

by kdr

in Marvin \ Video

in Marvin \ Video

If you have a large CRT, it's possible to have distinct scanlines in some of the standard VGA modes. On my 17" monitor the "EGA hi-res" mode (640x350) has quite distinct scanlines. The 350 line VGA mode is actually the exact same video timings as the double scanned 400 line modes (e.g. the 320x200 …

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Re: Why amstrad pc1640 won't boot?

Posted on 2021-12-11, 07:32

by

by kdr

in Marvin \ Software

in Marvin \ Software

Amstrad drive ID etc is set up more like Shugart standard than IBM's perverted version of standard, so while Amstrad drives can be got to work with IBM PC interfaces, it's gonna confuse the hell out of our friend here. Take cellphone pics of the jumpers before you start messing around. I think …

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Re: Why amstrad pc1640 won't boot?

Posted on 2021-12-11, 02:57

by

by kdr

in Marvin \ Software

in Marvin \ Software

If the floppy drives and media have been in storage for a while (sounds likely) you'll probably need to clean the magnetic heads in the drives and also clean the surface of the magnetic media inside the floppies. You may also need to clean and then lubricate the metal rails inside the drives; this …

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Re: Revisiting an x86-based alternative to the Raspberry Pi, optimized for retro gaming

Posted on 2021-12-07, 20:42

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Writing new Win98 drivers eliminates the need for any kind of custom hardware at all. At that point, we're basically asking ourselves what the best enclosure would be to use with the VIA EPIA-E900. It's not out of the question, but it does mean losing access to everyone's precious table fog and 8- …

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Re: So just how does DMA on a 8088 based PC work?

Posted on 2021-12-03, 17:49

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I considered creating a 8088 system design in verilog, but I can't find a cycle accurate model of the CPU. I was going to add the DMA circuitry to help understand how it worked. I have now bought a D8288 bus controller and another 8088. I will put together a maximum system and use a logic analyser …

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Re: So just how does DMA on a 8088 based PC work?

Posted on 2021-12-02, 20:09

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

As far as I'm aware you can't use the 8237's memory-to-memory feature on the IBM PC. When DACK0 is asserted, the IBM PC/XT motherboards are wired up so that this triggers a /RAS on *all* of the memory banks simultaneously and also skip the /CAS entirely. None of the memory chips output any data …

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Re: Old audio player from Windows 3.1 era that looked like a Hi-Fi system

Posted on 2021-12-02, 04:42

by

by kdr

in Milliways

in Milliways

Oh wow that screenshot brings back memories, I was also using this software (or something that looked very very similar) back in the 486/Pentium era...

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Re: Quandchrome EGA screen failure.

Posted on 2021-11-29, 20:05

by

by kdr

in Marvin \ Video

in Marvin \ Video

SVD wrote on 2021-11-29, 19:19: Since none of the TV-repair shops around answers my call, I really hope someone can help me with this You can also try posting at the VCF forums (vcfed.org) - there are a couple of members over there with a lot of CRT troubleshooting experience. (I'm thinking of Hugo …

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Re: Quandchrome EGA screen failure.

Posted on 2021-11-29, 01:04

by

by kdr

in Marvin \ Video

in Marvin \ Video

It's quite common for monitors of that era. A usual quick test for monitors in the 80s was to disconnect the input and turn up the brightness to 80%. You expected a light gray screen with small black borders left and right. The black borders in the OP are too wide, so the picture is suspect. The …

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Re: IBM 5160 earlier model motherboard repair question

Posted on 2021-11-26, 06:45

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Once you are certain that the physical switches are working correctly, if the switch still can't be read correctly then there's a problem in the 8255 PPI and the attached circuitry. The 8 switches are connected to 4 inputs of the PPI chip (PC0 .. PC3) and the PPI's PB3 output selects whether to read …

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Re: New motherboards for old sockets.

Posted on 2021-11-24, 08:49

by

by kdr

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

ao486 processor, IDE hard drive that redirects to a HDL SD card driver, floppy controller that also redirects to the SD card driver, 8259 PIC, 8237 DMA, Sound Blaster 2.0 with DSP and OPL2, 8254 PIT, 8042 keyboard and mouse controller, RTC, standard VGA. Wow, that's actually quite comprehensive - …

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