Re: Hardware mod for L1 cache support on Cyrix 486DLC/SXL CPUs

Posted on 2021-05-20, 09:02

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Never heard of that option. I'd still try that (on and off) with BARB and benchmark. It will be obvious if the CPU is flushing cache constantly, the performance will drop like a rock, possibly even below 386DX levels. Obviously the HW mod is better but software is easier and faster to configure and …

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Re: motherboard from HELL

Posted on 2021-05-19, 23:37

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It is possible your XTIDE image is not configured properly. Go to http://www.xtideuniversalbios.org/ and read about "Remove other hard drives" option.

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Re: Tandy 4825 sx Wont Post - Suspect Bios from codes. Anyway to make a new one?

Posted on 2021-05-19, 23:28

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Do make sure to run a verify on the EPROM after writing. And to make sure the chip itself is not very overused and too slow now, you can program it with the original BIOS image (no modifications). See if that works the same way as the original chip.

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Re: XTIDE and large (>8G) partitions

Posted on 2021-05-19, 23:24

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It just so happens that I'm tesing an ISA 3Com card that I intend to also use as XTIDE carrier and I refreshed my memory by re-reading some of the docs. The XTIDE pages states that "MS-DOS 7.x (Windows 9x) or FreeDOS is required to access more than 8.4 GB" - so your corruption probably happens when …

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Re: Hardware mod for L1 cache support on Cyrix 486DLC/SXL CPUs

Posted on 2021-05-19, 19:35

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

alexthekid wrote on 2021-05-19, 16:53: I want to run a 486DLC on a Soyo SY-19G 386 motherboard with an ETEQ 82C4901 cache controller. Why not try BARB first? No support for hidden refresh in BIOS?

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Re: motherboard from HELL

Posted on 2021-05-19, 09:57

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm kind of lost here, you test the card on two different PCs (that 386 from first post and some other Pentium system) and I don't know which one you're taking photos from. Well the last BIOS photo must be from P1 system, it's pretty new AWARD BIOS that supports LBA, so can't be 386. I'm not sure if …

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Re: Questions about my new AM386SX 33MHz system

Posted on 2021-05-18, 21:42

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is the program correctly identifying the CPU as 386SX? Because if it gives you the speed rating vs 386DX then all is good, the narrow SX bus causes about 20% performance drop vs DX. Rather then rely on the calculated speed, which is usually just a loop of slow instructions being timed, run some …

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Re: FIC 386SC - upgrades and testing

Posted on 2021-05-18, 19:55

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Can you add black bars on top and bottom to bump the vertical resolution to 480? I think it will try to match the closest otherwise and it's 360p, which is also pretty bandwidth starved and blurry. Static single-color bars cost next to nothing on modern video codecs. Though I'm not sure if YT …

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Re: Trying to understand 30pin simm memory modules capacity, please join if you can help.

Posted on 2021-05-18, 17:18

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Oh wow, my brain must be on vacation, or it's the weather maybe. I just couldn't process what you mean by 256kx4 until now. And yes, that makes sense - if I was to re-use 256kx4 die to make 1Mx1 then I'd also just add two flip-flops to store the highest order bit on both /RAS and /CAS and have that …

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Re: Tandy 4825 sx Wont Post - Suspect Bios from codes. Anyway to make a new one?

Posted on 2021-05-18, 10:15

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

OK, my bad. You have set the chip to 27C256, which is 32KiB device, but the dump you've made is 64KiB long from a 27C512 type chip. I should've paid more attention. In my defense I sometimes deal with older 286 mobos that have two smaller chips instead of one big so I didn't find it odd. So, set the …

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Re: MFM 5.25 floppy with 5ali61

Posted on 2021-05-18, 10:08

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Once set to 720k the drive should be able to format, write and read back from floppies it made, assuming you use DD media. Again, if there are problems with writing over previous 360k content then a demagnetizing will surely help. There aren't any PC 720k 5.25" disks, at least none I know of - so …

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Re: Trying to understand 30pin simm memory modules capacity, please join if you can help.

Posted on 2021-05-18, 09:54

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ah, I get it now. Your point is the 1Mx1 modules are mostly refreshed with 9 bits accross the board? Possibly because it allows older HW with narrow counters for 256k chips to "just work", you only need to extend the addressing, and also it lets you manufacture such chips in older process (albeit …

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Re: Trying to understand 30pin simm memory modules capacity, please join if you can help.

Posted on 2021-05-18, 09:09

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I already dug up data sheets to support that claim, see https://www.vogons.org/viewtopic.php?p=940479#p940479 I have that datasheet. I also have the datasheet for MB814400A which is 4Mx1 and has 1024 refresh cycles. So first, my bad, I was so focused on the row size that I didn't consider that …

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Re: Tandy 4825 sx Wont Post - Suspect Bios from codes. Anyway to make a new one?

Posted on 2021-05-18, 00:20

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes, except now you have a wrong file (or no file) loaded since it's full of FF, the last byte should've been 00.

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Re: MFM 5.25 floppy with 5ali61

Posted on 2021-05-18, 00:16

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

720k setting should work, but the problem is with media. You need QD floppies to have realiable write to them and 5.25" QDs are rare. It might just work with DD if these are good quality, but I'm not sure about longevity and error rates. And BTW all such flopies will have to be properly demagnetized …

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Re: Trying to understand 30pin simm memory modules capacity, please join if you can help.

Posted on 2021-05-18, 00:01

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Indeed. x4 chips (used on 3-chip SIMMs) typically need one more address bit for RAS-only refresh than x1 chips. x1 chips often ignore the highest address bit for RAS-only refresh, so boards not driving the highest address bit during refresh can work with 9-chip modules, but fail with 3-chip modules …

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Re: Tandy 4825 sx Wont Post - Suspect Bios from codes. Anyway to make a new one?

Posted on 2021-05-17, 23:47

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Basically I highlighted in red the last 00 i see, so i wanna change that to 5d? (i notice on the "output " side that adds in a bracket like ]) Er, how is it the last 00 if there are way more after it? Did you mean first? And anyway that's not the place. The last one, as in the very last byte of the …

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Re: Trying to understand 30pin simm memory modules capacity, please join if you can help.

Posted on 2021-05-17, 18:56

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Be very wary about these SIMMs. I have a set of 4 MB SIMMs like that, consisting of 3 chips of 4M x 4 each, so there are actually 12 bits to choose from. There are 0 Ohm SMD "jumpers" to choose 3 of the 4 bits of each chip, so the module uses 9 of the 12 bits present in the chips. Perhaps it's …

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Re: MFM 5.25 floppy with 5ali61

Posted on 2021-05-17, 18:44

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The 1015F MOD VI is QD drive - not very useful with PCs. All the cons and none of the pros. It's a nice drive, not doubt, I like these old things myself, but it's just not for PCs. It is 96tpi so has narrow head and can do 80 tracks, but that means not being able to properly erase/write to typical …

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Re: HWiNFO support of vintage hardware

Posted on 2021-05-17, 12:31

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have a feature request for HWiNFO for DOS - the decompression/decryption of the data structures is very slow when the program is run from a floppy drive. I could play around with DOS buffers and read-ahead but preferably it should work better on a clean boot system as well.

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