Re: Pentium 200 MMX Overdrive - Fan replacement?

Posted on 2021-04-23, 13:43

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Unlike the 83 MHz overdrive for socket 2, the 200MMX overdrive doesn't slow down without the fan. So you can remove the original and replace it. There is no overheat protection. When overheated, the CPU would likely crash.

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Re: 486DX-50 MHz EISA system

Posted on 2021-04-23, 13:01

by

by mpe

in Marvin \ System Specs

in Marvin \ System Specs

EISA has a 32 bit data bus so would be four times as fast as an equivalently clocked 8 bit ISA bus or twice as fast an equivalently clocked 16 bit isa bus. and it has a 32 bit address bus. Yes, in theory. The bus might be twice as fast if using 32bit writes to video RAM which is not common in DOS …

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Re: 486DX-50 MHz EISA system

Posted on 2021-04-23, 11:41

by

by mpe

in Marvin \ System Specs

in Marvin \ System Specs

Bus speed is the bottleneck. EISA cards are no faster than ISA and graphics performance is what's holding it back. With ELSA Winner 1000 in the EISA slot the Am5x86 @ 150 can produce about 20fps in DOOM on this motherboard. Only ~4ps more than with DX-50 with three times slower clock. An average DX2 …

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Re: 486DX-50 MHz EISA system

Posted on 2021-04-21, 20:53

by

by mpe

in Marvin \ System Specs

in Marvin \ System Specs

I finished it, but no longer have it and moved to other projects. The performance was adequate - a bit on slow side. Especially in graphics - simply there is no local bus and that's the biggest issue. I even tried to install AMD 5x86 @ 150 MHz which worked, but did not fly compared to DX2-66 on a …

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Re: 486DX-50 MHz EISA system

Posted on 2021-04-21, 19:41

by

by mpe

in Marvin \ System Specs

in Marvin \ System Specs

, there are some around the CPU (w21, w22, etc...) that are not listed, pretty sure they change the bus speed (but not had a chance/ time to just do trial and error changes), tried just swapping the crystal once, but no joy. I no longer have this build, but I was able to find out the purpose of …

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Re: Life expectancy of an "old" HDD

Posted on 2021-04-21, 12:08

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There is also survivorship bias as many old hard drives that used inferior parts prone to worn out, manufacturing defects, etc. likely already failed years ago. So those surviving ones are almost always the best ones. That's why people might consider old hard drives more durable.

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Re: Life expectancy of an "old" HDD

Posted on 2021-04-21, 09:45

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Life expectancy of hard drives is a well researched problem. https://www.extremetech.com/wp-content/uploads/2013/11/backblaze-bathtub-failure-rates-graph.jpg There is a spike at beginning of their life and they decrease until it gets up again as the drive gets older. However, with vintage hardware …

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Re: Identifying bad caps on motherboards

Posted on 2021-04-21, 07:24

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Just ordered this device: s-l1600.jpg The device advertises in-circuit capacitance/ECR testing (given by using 100 kHz pulses and low voltage). Will see how it goes! In worst case I can always use it to test desoldered parts. I am only concerned that I read somewhere that some motherboards …

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Re: Identifying bad caps on motherboards

Posted on 2021-04-20, 21:24

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I know about the fake cache crud though fail the see the connection to this bad caps thread... Pictures above (still want to hear opinions about the cap) are showing Aptron DX-9700 which features a dummy cache. However, the DX-9700 has also COAST slot that can host a real cache. It is actually a …

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Re: Identifying bad caps on motherboards

Posted on 2021-04-20, 14:15

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I think replacing everything could be one strategy. I personally prefer not to touch vintage stuff with solder unless I have to. But when troubleshooting issues, it helps if you know that there is (or was) a problem. I was thinking about using oscilloscope to identify weird looking edges, but this …

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Identifying bad caps on motherboards

Posted on 2021-04-20, 12:14

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I was wondering how to identify bad caps that need replacing. I think it is somewhat easier for bigger caps which are visibly bulging or leaking. But those tend to came on later boards Pentium II+ Many 386/486 stuff only have smaller 10-100µF parts which don't bulge as much. However, I noted that …

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Re: 486DLC cache coherency blues and headaches

Posted on 2021-04-20, 08:14

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If everything works fine with the 386DX then SRAM chips are likely OK. And since you tried to increase waitstates faster chips are unlikely to help. Capacitors might or might not be the issue I am just mentioning them that they are relatively easy to replace and they often create issues. Unlike …

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Re: 486DLC cache coherency blues and headaches

Posted on 2021-04-20, 06:41

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Does the L2 cache work fine on its own without having L1 enabled or is it always crashing when the L2 is on? I suppose you tried adding read/write waitstates in the cache settings (5th screen) already and it still didn't work? What if you exclude all <1M memory from cacheable range? If you have …

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Re: Bought these (retro) hardware today

Posted on 2021-04-17, 18:47

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

megatron-uk wrote on 2021-04-17, 17:15: My understanding is that they have a small amount of SRAM embedded in each DRAM chip, is that correct? Yes there is 8KB of fast embeded cache (or 512B per 1MB DRAM) which allows for eliminating latencies during reads/writes (zero waitstates up to 133 MHz).

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Re: 486-era Gimmicks PC

Posted on 2021-04-17, 10:04

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Nice one. Might make more sense to go for Gravis Ultrasound ACE rather than Classic as the latter is a resource hog (considering a number of periherals you want to use in your system).

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Re: Bought these (retro) hardware today

Posted on 2021-04-17, 09:47

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

PC-Chips M919 with hilarious dummy L2 cache in the top right corner (and luckily also the actual COAST module in the slot). https://dependency-injection.com/wp-content/uploads/2021/04/DSC_9939-scaled.jpeg And two elusive 15ns ED RAM SIMM modules. https://dependency-injection.com/wp-content/uploads/ …

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Re: Bought these (retro) hardware today

Posted on 2021-04-12, 16:37

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Inspired by some positive reviews I bought this desoldering gun. Quickly tried to remove a few caps and NiCD battery from my boards and it makes an amazing difference compared to the butchering I've done before. I should have bought this years ago! Filename DSC_9595.jpeg File size 813.11 KiB Views …

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Re: Chips & Technologies F64300 VLB vga question

Posted on 2021-04-08, 19:57

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The cache only works for GUI acceleration and improves performance by about 15%, depending on resolution. DOS is not constrained by the video memory bandwidth and thus there is no improvement.

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Re: ABit AB-PT5 CMOS battery?

Posted on 2021-04-07, 15:41

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I got a ABit AB-PT5 rev 2.11 mobo a few months ago but now I am getting the dreaded error (at boot time): CMOS checksum error - Defaults loaded CMOS battery failed Ok, I get it, the battery is dead but where is the battery? I cannot find anything like a battery in the mobo to replace :| The battery …

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Re: Bought these (retro) hardware today

Posted on 2021-04-07, 15:24

by

by mpe

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have no use for another SCSI RAID adaptor. But I was trying to source EDRAM modules for my Octek Hippo-VL DCA board for a while and recently bought two SCSI adaptors that might come with some. I hope that's what I need (seller's picture). Filename s-l1600.jpg File size 88.35 KiB Views 518 views

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