Re: Additional ram recognized but not usable

Posted on 2024-04-13, 07:50

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I tested three 8 chip DIMMs and they all tested out at the correct capacities, 64MB, 128MB, and surprisingly 256MB on both the EX & BX chipsets. HYB39S64800CT-8 - 4 banks × 2 MBit × 8 HY57V28820HCT-H - 4 banks × 4 MBit × 8 HYB25D25600BT-6 - 4 banks × 8 MBit × 8 The 256MB one is really strange. …

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Re: Floppy disk problem

Posted on 2024-04-09, 20:48

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You might try a different IDE Interface Card as well. Maybe another one will not respond to 3F7 at all.

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Re: Floppy disk problem

Posted on 2024-04-09, 18:37

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Tried a few new drives and cables same problem, added normal drive back problem was gone note sure if the cf card is the problem but without it . Works like it should The CF card might indeed be the problem. This is one of the very strange designs in the IBM AT: The ISA I/O port 3F7h is shared …

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Re: Asus VL/I-486SV2GX4 with 60MHz bus?

Posted on 2024-04-09, 18:26

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

One thing I find odd is that no chipset manufacturer in the VLB era ever considered implementing the IDE controller inside the chipset for higher performance. That would have made the VLB solely a dedicated graphic port, as it happened with AGP a few years later. Some late 486 chipsets have an …

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Re: Can a faster ISA Graphics card be built?

Posted on 2024-04-09, 17:45

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by mkarcher

in Marvin \ Video

in Marvin \ Video

DOS text mode output (80x25) can be done with just 230kB/sec Not really. On the PC, there is no "line cache", so each text line needs to be retrieved for each scan line of the character. For example, on CGA, in high-res text mode, a character takes 8 pixels at 14.318MHz pixel clock, which is 1.8 …

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Re: It is possible to safely repair a DRAM module with a bad pin?

Posted on 2024-04-09, 07:36

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If the gap is to large to bridge with solder many, myself included like to use the leg from a cap or resister. In the case of the fine traces of an SDRAM modules, a capacitor or resistor leg may be too bulky. In that case, I use single strands from stranded wire. You don't have to cut the tiny …

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Re: Can a faster ISA Graphics card be built?

Posted on 2024-04-09, 07:27

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by mkarcher

in Marvin \ Video

in Marvin \ Video

While you had one wait state on expansion cards for 16-bit cycles on the AT (just as the AT also used for RAM), RAM cards (and other cards that claim areas of 128KB contigous memory address space) can remove that wait state for memory cycles by activating the /0WS signal, and thus operate at …

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Re: Can a faster ISA Graphics card be built?

Posted on 2024-04-09, 06:52

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Shagittarius wrote on 2024-04-08, 22:35: I'd rather see an ISA card with a HDMI or DP out that does internal upscaling to 4k. Actually I'd like that for a PCI card too. Without upscaling, there is the CRT Terminator: CRT Terminator Digital VGA Feature Card ISA DV1000 .

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Re: Multimeter recommendation

Posted on 2024-04-08, 20:17

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

boby wrote on 2024-04-08, 20:09: Which brings me to one more feature I would like it to have, and that is that it has automatic value change. The usual name of that feature is "autorange" or "automatic range selection".

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Re: Can a faster ISA Graphics card be built?

Posted on 2024-04-07, 23:27

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by mkarcher

in Marvin \ Video

in Marvin \ Video

However, backwards compatibility with the older architecture (IRQ, DMA, 8-Bit i/o, ~14 MHz clock pin) and existing PC cards caused performance penalties. The 14MHz clock pin is not related to bus performance at all. No bus cycles are synchronized to that pin (except, of course, if the system clock …

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Re: Video RAM chips for a UMC TK-85C408VGA ISA Video Card?

Posted on 2024-04-07, 21:33

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Cheers, some pics would be helpful. As promised, the pictures of my card. It's a bit dirty but I'll ty to clean it as soon as I can. It uses the same chip model as suggested by @pshipkov, but with a different speed. This picture clearly shows that the 85C408AF does support 1M of video memory …

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Re: Can a faster ISA Graphics card be built?

Posted on 2024-04-07, 21:24

by

by mkarcher

in Marvin \ Video

in Marvin \ Video

However, backwards compatibility with the older architecture (IRQ, DMA, 8-Bit i/o, ~14 MHz clock pin) and existing PC cards caused performance penalties. The 14MHz clock pin is not related to bus performance at all. No bus cycles are synchronized to that pin (except, of course, if the system clock …

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Re: Can 32-bit x86 programs explicitly use IP?

Posted on 2024-04-07, 21:15

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by mkarcher

in PC Emulation

in PC Emulation

Can 32-bit x86 programs even explicitly use IP instead of EIP(which uses masking on the high 16-bits when loaded this way) during fetching (like SP vs ESP)? The decision whether IP or EIP is used as offset to CS when fetching instructions is the "D/B" bit of the code segment descriptor. If you call …

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Re: Who regconize this AT IDE controller?

Posted on 2024-04-07, 20:50

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Board has markings like: 070-5-0490. But iam guessing 04 - 90 could mean like month 04 1990. I don't think this is a date code, but some internal design number. Yellow sticker on the board says 9124.. -> 1991 , week 24? This seems likely. What clear is that the jumper settings (on the bottom) are …

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Re: Can a faster ISA Graphics card be built?

Posted on 2024-04-07, 20:30

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by mkarcher

in Marvin \ Video

in Marvin \ Video

By the time you add graphics to the board, then extra RAM to the board because the ISA is too slow, then maybe another x86 CPU to the board because the ISA is too slow, and move another couple of things to the board because ISA is too slow... you may as well be using a Powerleap Renaissance …

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Re: Additional ram recognized but not usable

Posted on 2024-04-07, 20:22

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here are the DIMMs that I tried: Showed 1/2 size: 4 chip DIMM - Hynix 256Mbit (4Mbit x 16 x 4 bank) Showed 1/2 size: 16 chip DIMM - Micron 64 Mbit ( 2Mbit x 8 x 4 bank ) Showed 1/2 size: 4 chips DIMM - Generic 256Mbit (16Mbit x 16 ) Showed full size - 16 chip DIMM - Epida 64Mbit ( as 2Mbit × 8-bit …

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Re: Multimeter recommendation

Posted on 2024-04-07, 10:23

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Dunno man. I had one of the cheapest, and it always had a ~1 second delay in continuity mode. That is, you need to hold the probes for over 1 second to make it beep. Was very happy when I got rid of it and went for something a little bit better for about 30$ USD: I agree, this is a very important …

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Re: Video RAM chips for a UMC TK-85C408VGA ISA Video Card?

Posted on 2024-04-07, 08:27

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by mkarcher

in Marvin \ Video

in Marvin \ Video

I'm wondering if I can swap these four 256 K x 4 chips with four 512 K x 8 chips with some disabled data lines and used as 512 K x 4 for a total of 1 MB VRAM (that idea came to me from the six chips version of the card where are used some "low-grade" chips with reduced number for data lines). I …

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Re: Rare card or just forgotten?

Posted on 2024-04-06, 20:12

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Will I need to use the 9-pin for a colour image? Or is it just my monitors that won’t lock on to the signal correctly? In CGA mode (your card obviously is in CGA mode now, if you get an image on your TV), I expect that at least some DIP switch combination will output something that resembles a …

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Re: Video RAM chips for a UMC TK-85C408VGA ISA Video Card?

Posted on 2024-04-06, 18:56

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by mkarcher

in Marvin \ Video

in Marvin \ Video

Hmmmm hope that is the case for the UMC card I turned up the other week also, had two out of four chips removed, when someone figured it may as well only be a 256KB VGA I guess because 512 wouldn't seem to do much for it. If it's that other problem with only the good half of the chips actually used …

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