Re: EGA Video cards - BIOS image collection

Posted on 2022-01-27, 20:05

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

#19 Manufacturer/Identifier: Citygate Chipset: Citygate D10 BIOS-String: IBM COMPATIBLE.*EGA BIOS V1.6a COPYRIGHT Award Software Inc. Status: Card is untested EGA - Citygate D10 front.jpg EGA - Citygate D10 back.jpg DIP Switches: 1--2--3--4 on-off-off-on = 40x25 Color monitor off-off-off-on = 80x25 …

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Re: Oak Technology VGA-16 (OTI-037C based mda/cga/ega/vga) video card schematics?

Posted on 2022-01-26, 09:22

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here's the pinout of that PAL design. u12_pinout.PNG Wrote the PLD design that decodes I/O ports access signals and VGA memory areas. It all looks ok in simulation, but still didn't bring up the card to life. It's possible some other ICs are not ok, so I'd need a full-blown debugging on a breadboard …

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Re: Oak Technology VGA-16 (OTI-037C based mda/cga/ega/vga) video card schematics?

Posted on 2022-01-25, 09:18

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Seems I have a bit of luck with reverse engineering approach. The dead PAL is only involved in generating IOR#, IOW#, ASEL and RESET signals for the OTI-37c, so basically only detects the addressing of VGA memory area and distinguishes I/O ports access from DMA transfers and refresh conditions. It's …

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Re: Oak Technology VGA-16 (OTI-037C based mda/cga/ega/vga) video card schematics?

Posted on 2022-01-24, 14:53

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yeah, I've seen the datasheet for OTI-37c. Problem is - there are many cards built on this chip, and the PAL is typically used in glue logic around the chipset, implementing decoding of address and other control lines logic. This varies wildly between cards, and the equations in this dead PAL are …

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Oak Technology VGA-16 (OTI-037C based mda/cga/ega/vga) video card schematics?

Posted on 2022-01-24, 13:29

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Got this board, it's not detected by bios. oak-vga-16.jpg Probing the power lines I see some suspiciously low resistance (88 Ohms, or 0.17v drop when measuring in diode testing mode). It's not dead short, but still way too low. To avoid desoldering all tantalum capacitors I started with taking out …

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Re: ISA GPU for 286 Build

Posted on 2022-01-24, 12:21

by

by vstrakh

in Marvin \ Video

in Marvin \ Video

These cards worked for me just fine on the Harris 286 @20 MHz. Cirrus Logic CL-GD54210 Filename cl-gd5420.jpg File size 594.42 KiB Views 139 views Trident TVGA9000c Filename trident tvga9000c.jpg File size 504 KiB Views 139 views

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Re: Troubleshooting 386 motherboard, video memory writes clashes with PCM audio playback

Posted on 2022-01-23, 20:38

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Same PSU (300W ATX) is ok with two another PC's - Harris 286@20MHz (running video+audio) and Pentium MMX @166 MHz (also video+audio+cdrom). This is where I know the cards are ok. In all cases CF is used instead of HDD, so the load is even less than it would be normally. But yeah, maybe it's worth …

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Re: Troubleshooting 386 motherboard, video memory writes clashes with PCM audio playback

Posted on 2022-01-23, 10:12

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Tried ES1868 (with esscfg for pnp config) and Aztech AZT2320 (unisound 0.77 for pnp config). For video tried Cirrus Logic CL-GD5420 and Trident 9000c. All build permutations with these cards produced identically looking issue. Trying to reorder the cards in the ISA slots also had no apparent effect …

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Troubleshooting 386 motherboard, video memory writes clashes with PCM audio playback

Posted on 2022-01-22, 17:09

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have a Bioteq MB-1333 motherboard. It's am386dx-40 based ISA mobo, built on a Bioteq-rebranded UMC 82c491 chipset. It's working ok and all, up until I try some games with pcm samples being played. It looks like audio samples gets garbled when the screen is intensively updated. There is definitely …

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Re: Introducing HWiNFO16 (for 8086/88/186/188/286)

Posted on 2022-01-21, 20:52

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is it ok to use this build on a 386 pc, or detection of cpu's above 286 was entirely removed? I have a 386DX40 board with IIT 3c87 math coprocessor. This app version does not show the cpu type or frequency, and misidentifies the coprocessor for Intel 8087 @ 122 MHz. It detects the chipset correctly …

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Re: Does anyone own a MISTer FPGA and how is it?

Posted on 2022-01-21, 19:35

by

by vstrakh

in Console & Arcade Emulation

in Console & Arcade Emulation

Each individual chip in a SNES for example is not described exactly in HDL, where each chip has a different set of timing and clock cycles and the interactions between each chip are described faithfully, instead operations are approximated and batched together at acceptable timing It's not …

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Re: Bought these (retro) hardware today

Posted on 2022-01-21, 10:34

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Bought a nice 386DX-40 motherboard with ram/cache/NPU included. It's a Bioteq MB-1333/40UCQ-B. And the NPU is IIT 8c387-40 😀 The battery is GP, not Varta. It's still nice and shiny, no corrosion or salts deposits. Filename Bioteq MB-1333.jpg File size 770.01 KiB Views 440 views

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Re: Does anyone own a MISTer FPGA and how is it?

Posted on 2022-01-21, 08:09

by

by vstrakh

in Console & Arcade Emulation

in Console & Arcade Emulation

the mister has less latency is because there is no OS getting in the way, as all the software runs on it bare metal. In theory you could could run software emulators bare metal on a raspberry pi or an x86 pc and they would be just as good. The fpga vs sw is not about os vs bare metal. The cores in …

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Re: Weird text character showing up in Pentium 1?

Posted on 2022-01-18, 20:19

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I had similar issues with ISA video card not making good contact in the slot. Reseating the card or moving it to other slot usually fixed this.

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Re: Does anyone else have any issues with the "MIDI IN 1" socket on their SC-55mkII?

Posted on 2022-01-18, 08:29

by

by vstrakh

in Marvin \ Sound

in Marvin \ Sound

Kahenraz wrote on 2022-01-17, 23:35: It's completely off-pitch! Does it react to "key shift" controls with the front panel buttons?

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Re: CD-in Audio - where to find for my SB Pro clone

Posted on 2022-01-15, 15:23

by

by vstrakh

in Marvin \ Sound

in Marvin \ Sound

Looking at the website, for example Mitsumi, there are these wires on the 4-Pin side: - right channel signal - right channel return - left channel signal - left channel return No ground? The ground is the return path in unbalanced interfaces. Since your drive doesn't have the balanced output, …

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Re: CD Emulator

Posted on 2022-01-13, 17:50

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by vstrakh

in DOS

in DOS

There was no subst with cd emulation, It was cdemu after subst.

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Re: Games with Adlib as an option for sound effects

Posted on 2022-01-13, 08:13

by

by vstrakh

in DOS

in DOS

The Flashback can use the Adlib for SFX. I remember I did hack it to make it play sounds using Covox clone instead of Adlib that I didn't have at the time.

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Re: Help for jumper of 486 motherboard

Posted on 2021-12-27, 13:32

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ah, ok. I've assumed that was the current state on the photos.

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Re: Help for jumper of 486 motherboard

Posted on 2021-12-27, 13:01

by

by vstrakh

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is there a jumper shorting out the JP8, which is supposed to be a LED output?

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