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Re: Analyzing old CPUID code

Posted on 2023-05-29, 05:34

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This seems like it would have disastrous results if attempted from protected mode thus it wouldn't make sense for the CPU utility running under NT discussed in the other thread where this was coming up. Executing a CPU reset switches it to real mode (and that was the only way to get a 286 processor …

Re: Analyzing old CPUID code

Posted on 2023-05-27, 07:35

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I noticed the HWINFO utility (from Mumak, here on vogons) comes with a readme file that talks about ways of obtaining the CPUID from pre-CPUID processors, including temporarily overwriting the BIOS. It also describes forcing a reset with A20 disabled. I suppose that would cause the reset vector to …

Re: CL-5446 being better than S3 Trio64v+ ?

Posted on 2023-05-14, 22:39

in Marvin \ Video

in Marvin \ Video

Also, would this card be upgradable to 4MB as shown here in the link ? http://old.vgamuseum.info/palcals-collection/61-cirrus-palcal/1044-cirrus-logic-cl-gd5446-hc-a.html No, it won't be. Those memory chips are mostly universal on all those cards, and contain 0.5MB. The 5446 cards contain 2 or 4 …

Re: Help with repair 286 mainboard

Posted on 2023-05-11, 20:31

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Archon wrote on 2023-05-11, 13:21: Once I removed the PAL, I saw that the socket is slightly corroded so I gave it a little cleaning and voila! Wow! This means that my idea about a missing GND connection of that PAL (no contact on pin 10) could actually be the root cause of your issue. Thanks for …

Re: ISA RAM CARD using 30 pin SIMM ? ON XT Class machines?

Posted on 2023-05-10, 21:20

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I wasn't referring to bus transceivers. More like gating the memory read/write strobes from ever going active on the ISA slots if the onboard memory is serving the access. So, I got around to check the IBM schematics. Contrary to my previous post, there is no I/O steering. All I/O and memory read …

Re: Schneider Euro PC

Posted on 2023-05-10, 19:11

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Also wondering, I have amiga rgb to hdmi board, would it be possible to get it to work with xt machine? The Amiga uses analog RGB (like VGA). CGA, EGA and Hercules use digital RGB. If you can't reconfigure your RGB to HDMI converter, you will get 8 colors at max from a video card with analog output …

Re: ISA RAM CARD using 30 pin SIMM ? ON XT Class machines?

Posted on 2023-05-10, 19:08

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I wasn't referring to bus transceivers. More like gating the memory read/write strobes from ever going active on the ISA slots if the onboard memory is serving the access. OK, now I got what you meant. I will take a look into the 5150 64K mainboard schematics I have at hand shortly. I don't …

Re: CL-5446 being better than S3 Trio64v+ ?

Posted on 2023-05-10, 17:43

in Marvin \ Video

in Marvin \ Video

Regarding the CL card, how much RAM does it come as a standard / unpopulated ? Are the socketed RAM found on the S3 Virge compatible with the CL one ? I would like to answer those questions, but the photos are not good enough to read the model number of the RAM chips on either the Virge card or the …

Re: ISA RAM CARD using 30 pin SIMM ? ON XT Class machines?

Posted on 2023-05-10, 17:34

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If it does not have RAM data buffer chips, just not installing mainboard RAM chips is enough to keep the bus free. If it does have buffer chips, you need to find out how to disable them (jumpers?) or in case of socketed dedicated buffer chips just for memory pull them. This presumes the onboard …

Re: Connect a AT power supply to the power button

Posted on 2023-05-10, 05:59

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What about this would damage the switch, especially since the fuse went out? Too many amps across the switch terminals, could melt/insta-weld them together. Exactly. For Germany: General-purpose circuits with sockets typically use 16A breakers, type "B". For that breaker to switch off immediately, …

Re: ISA RAM CARD using 30 pin SIMM ? ON XT Class machines?

Posted on 2023-05-10, 05:52

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Most LIM4 and EEMS boards only allow you to backfill down to 256kb. The purpose of my experiment was to see if the entire 640kb could be backfilled. Perhaps with the right card/motherboard combo it might work? You need to make sure that the motherboard doesn't drive the data bus when accessing the …

Re: What should I do with this problematic CRT monitor?

Posted on 2023-05-10, 05:48

in Marvin \ Video

in Marvin \ Video

Anything is more productive than trying to revive 20 year old smashed CRT :) Except if the goal is to get some experience in tuning worn-out CRT devices. You never know what people enjoy in the Retro Hobby. Is it playing old games? Is it getting a good rig? Is it fiddling with the stuff? Is it …

Re: Help with repair 286 mainboard

Posted on 2023-05-09, 21:47

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Did this mobo work at all? Or did you get it in this state? If the PAL chips are socketed then perhaps someone removed them and then put back into wrong sockets. Or, perhaps, just put some random PAL in place of a missing one to sell the mobo as complete (no missing chips). I see two PALs with …

Re: ARK Logic VLB wait states

Posted on 2023-05-09, 21:33

in Marvin \ Video

in Marvin \ Video

Wow, thanks, that's informative . I have two jumpers, both on default settings, CPU ADS# Signal and CPU RDY# Signal Delay . Not sure what these are, or do they matter at all. The card is quite fast already, I just wanted to check if there is an easy way to push it even further. CPU RDY# Signal …

Re: ISA DMA issues in DOS with SiS 496/497 based motherboards

Posted on 2023-05-09, 06:24

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Did you find which jumper does it ? While I won't give you a 100% guarantee, the findings I gathered from the manual and the measurements taken by feipoa strongly suggest that on the Rev D board, the L1 cache mode jumper for AMD 5x86 processors (and Intel 486DX2/DX4 &EW processors) is JP8, pin 6-7. …

Re: ISA DMA issues in DOS with SiS 496/497 based motherboards

Posted on 2023-05-09, 06:19

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I did not see your edit. The continual edits in this thread have made it hard for me to follow. So my edit was too late. I will try to get used to making a new post instead of editing if I have to add significant new information, and maybe just edit a hint to the new post into the old post (so …

Re: What should I do with this problematic CRT monitor?

Posted on 2023-05-09, 05:32

in Marvin \ Video

in Marvin \ Video

Thanks for the info. I did a Google image search for CRT flyback transformer and found that most have two trim pots labeled "focus" and "screen." Would "screen" be the G2 voltage? Exactly. "Screen" and "G2" are two different names for the same electrode in the CRT. The name "screen" at this point …

Re: Help with repair 286 mainboard

Posted on 2023-05-08, 21:23

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here we go: 1. CE on RTC goes high for a very short while after power on, and then goes low. After turning power off it goes high and then slowly goes to zero. 2. 74ALS74AP: - pin 1 and 4 are high all the time - pin 2 - high for a short period of time and then stays low - pin 3 - 24MHz, Vpp 3.5V - …

Re: Original Voodoo 5 6000 prototype for sale on eBay

Posted on 2023-05-08, 21:18

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Don't the 3DMark programs test DirectX performance? What is the point of running them on a Glide card? In the end, all the pre-T&L-cards are basically hardware-accelerated texture mappings and triangle color interpolators with slightly varying feature sets. DirectX 6 is an abstraction layer over …

Re: Is Cirrus Logic CL-GD5426 VLB any good?

Posted on 2023-05-08, 17:30

in Marvin \ Video

in Marvin \ Video

So the card itself sends /LBS16, but still has to obey /BE[0-3] and handle word steering on its own. Exactly. /LBS16 does not do any byte/word swapping. It just tells the processor that if /BE0 or /BE1 was asserted for the cycle, /BE2 and /BE3 were ignored and the processor should re-issue a bus …

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