Re: Non-US character ROMs from MDA/CGA/Hercules cards?

Posted on 2020-12-05, 21:34

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

VileR wrote on 2020-12-05, 18:21: @muon: have you verified that you actually need to do this? That image (and .bin) is of the standard CP437 character set, which includes those chars for Spanish. Good call, I should have checked that before explaining how to program a ROM that most likely wouldn't …

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Re: Unknown Socket 3 board

Posted on 2020-12-05, 16:28

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This looks like a late VLB only 80486 mainboard, obviously optimized for minimal board size. This is in line with the mainboard design date printed on the back side: 9445 means 45th week of 1994. The cache chips are 512kBit chips, which were uncommon in the early 486 days, so boards usually used two …

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Re: Non-US character ROMs from MDA/CGA/Hercules cards?

Posted on 2020-12-05, 15:47

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Second: the picture that I show in my previous post is of the set of font I'm interested (ñ Ñ : I took from a message of previous page of this thread), but I don't know how get the current font set of my card. How I should proceed? The message you took the image from also contains a ZIP file. That …

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Re: Non-US character ROMs from MDA/CGA/Hercules cards?

Posted on 2020-12-05, 11:42

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The font you show is a 8x8 CGA font. A CGA font is 8 bytes per character at 256 character, i.e. 2 kilobytes. Your ROM chip has 8 kilobytes, and your card is very likely to use one of the four 2-kilobyte parts you obtain when dividing the 8 kilobytes into 4 equal parts for CGA display. If you obtain …

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Re: Help identity VLB controller

Posted on 2020-12-05, 09:10

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Need to identify this controller, I know the headers for com ports are missing and I want to be sure nothing else is missing before testing it ) as it has dual floppy headers. It looks like the missing ICs (IC2/IC3 and the one near the ISA connector) are all about the optional BIOS ROM extension. …

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Re: AWE32 CT2760 Speaker Out Port

Posted on 2020-12-04, 17:38

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

Line out port emits normal sound, but absolutely nothing comes out from the speaker port which is usually what I use with my headphones. Does anyone have any idea if there's some configuration required to enable this port, or is it likely damaged? If the problem is not caused by insufficient output …

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Re: Tekram DC-680T seemingly not working

Posted on 2020-12-04, 17:25

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

6% 80186 internal timer failed (or VL clock too slow) 25% No cache RAM detected 50% 80186 register failed (broken chip) 75% On-Board SRAM failed 25% duty cycle means that the LED is lighting up 25% of the time, and being dark 75% of the time. The below is a link to an image of the card, it appears …

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Re: Tekram DC-680T seemingly not working

Posted on 2020-12-03, 21:38

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

After last nights panic with the VLB 486 (don't ask) I decided tonight to take a look at a VLB controller I picked up from eBay a while back, in particular this is the Tekram DC-680T. Its possibly dead though as on boot it gives a looping single flash on the LED and an error message "Controller …

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

Posted on 2020-11-06, 18:26

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Hello I am back with first life sign of Virge...ähm...Trio64V+ VLB. I am waiting of Virge donate. ( one is in transit to me ) Great! How do you decode SAUP1/2 now? Nice. Any chance of Virge /DX also supporting VLB? It would be more attractive choice... Sorry, that won't work. The S3 Virge (no …

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Re: Ensoniq SoundScape S-2000 Corrupt MIDI Playback

Posted on 2020-11-03, 20:43

by

by mkarcher

in Marvin \ Sound

in Marvin \ Sound

I was digging through my old parts bin and got pretty excited to realize that I had an early Ensoniq SoundScape that I had completely forgotten about. My excitement was quickly dashed when I placed it into one of my retro systems and tried the MIDI playback. https://youtu.be/3zYyx587qok The digital …

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Re: Troubles between a PCI/ISA POST card and my Asus P55T2P4-C motherboard

Posted on 2020-11-03, 20:38

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I got the same card as OP (A311L5G1112), started searching the web for the manual but no luck so far. Anyone perhaps has a link to manual (or a link with post codes will do), the one that came with it is in chinese... The POST codes do not depend on the card you use, but only on the kind of BIOS. …

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Re: Doble Help - identify MOBO (WD286-min) and vga output - lm339D

Posted on 2020-11-01, 23:14

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I would need some help to understand which motherboard is the one in the photos and then if someone helps me to understand the VGA output circuit, I would have identified a problem in the lm339D but I don't understand the circuit. Color Palett IC RED ----- m339D GREEN -- m339D BLUE ---- m339D The …

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Re: Let's make some memories (SIMMs)

Posted on 2020-10-31, 19:29

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This is a bit offtopic, but can anyone confirm if 24 bit address are passed to memory modules in different clock cycles to allow modules of more than 4 MB? Are you talking about 30-pin SIMM modules? They don't have "clock cycles", but a row address cycle and a column address cycle. Both the row and …

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Re: Identify 2 ISA cards

Posted on 2020-10-31, 17:35

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The unknown board is a good exercise for reverse engineering an ISA card. No custom PALs on them, most traces visible, not too complicated. I will still spoil the result: It seems to be an 8-bit digital I/O card with opto-isolated floating inputs and open-collector outputs. It mostly works like …

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Re: Identify 2 ISA cards

Posted on 2020-10-30, 22:17

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The unknown board is a good exercise for reverse engineering an ISA card. No custom PALs on them, most traces visible, not too complicated. I will still spoil the result: It seems to be an 8-bit digital I/O card with opto-isolated floating inputs and open-collector outputs. It mostly works like this …

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Re: external l2 cache issue - 486 socket 3 mobo

Posted on 2020-10-29, 23:43

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

[quote=Robhalfordfan post_id=906519 time=1603995029 user_id=34664] i didn't know that - what would the chip type be there as i have selcet the ic type before reading the chip [/quote] Manufacturer: "Standard SRAM", Model: "62256" (For the usual 256kBit chips, where 8 of them yield 256KByte L2 cache …

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Re: Questions about Bios in low and high files

Posted on 2020-10-27, 05:51

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I get the impression that the interleaving ("merging") was done correctly, but the result is larger than one segment so IDA has to be told how the memory is mapped. What's the size of the ROM after merging? 128K? Normally a 64K system BIOS is loaded at F000. With larger ones I don't know if you can …

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Re: IBM 486SLC2 - cache info

Posted on 2020-10-25, 22:54

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

On the 386SX, the ADS# is output only, and asserted by the processor when all of the pins have been set up properly for a bus transfer. It turns out that on the IBM 486SLC2, this pin is I/O. The chipset asserts it during a DMA cycle, and the 486SLC2 uses this as a hint to snoop the WR#/MIO#/address …

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Re: Some questions about a Hercules card

Posted on 2020-10-25, 07:37

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You use a 2764 or a 27c64. An 2864 or 28c64 should be compatible. The chip you need is named "74LS374". The card already says "LS374" on the silkscreen, and the 74 was supposed to be obvious to anyone into digital electronics. There are more modern variants of this chip that should be 100% …

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Re: PS/2 mouse: polling rate vs. sensitivity

Posted on 2020-10-24, 20:08

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Your understanding of the issue seems completely correct. As you describe it, the older mechanical mice are not operating properly at a sample rate of 200 Hz. There are many conceivable technical reasons for the mouse to malfunction (at least in a pronounced way) at 200 Hz. The first one that comes …

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