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Compaq Presario 433, my 486 pure DOS machine

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Reply 60 of 80, by 386SX

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What a great computer the Presario 433/425. A friend had it and we played the game Stunts on it million times when I had the 386SX20 and I couldn't run it full detail and smooth fps. Not for the cpu but probably for the OTi37C vga I think to remember, the difference from my 386SX and its 486SX was like night and day.
That Compaq I suppose had a S3 805 VLB on board (or a Cirrus Logic can't remember) and that was the great boost but I was convinced that its 4MB of ram was the reason of that so we upgraded to 4MB even my 386 (the max the mainboard could support) and nothing changed obviously, beside Win 3.1. I wasn't a video card "expert" in the 1994 and I didn't even know how much faster that config was compared to the cheap low end of my 386 based one. 😀
Much later I found the very same Compaq used but the more you open the mainboard the more you can break something of the case considering the force to use to correctly close the back part. Also I wouldn't try too many different rams, at the end my pc died for unknown reason upgrading it.
Anyway I remember having used a 486 Overdrive 66Mhz on it easily, ram up to 20MB, network card..Sometime I hope to find another one again.

Last edited by 386SX on 2020-05-22, 14:05. Edited 3 times in total.

Reply 61 of 80, by Pierre32

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425 owner here. Such neat little machines 😀

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Mine's running the stock SX/25 CPU. I've maxed the RAM to 20MB and installed an SB16.

And since the thread is bumped, I might as well answer a 3 year old question...

tabm0de wrote on 2017-02-07, 09:36:

Is there anyone that know where i could maybe find the copy of the recovery disk for Compaq Presario 433?

Someone uploaded this last year: https://archive.org/details/compaq425433filesmsdos62

Reply 62 of 80, by 386SX

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Pierre32 wrote on 2020-05-21, 13:08:
425 owner here. Such neat little machines :) […]
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425 owner here. Such neat little machines 😀

425.jpg

Mine's running the stock SX/25 CPU. I've maxed the RAM to 20MB and installed an SB16.

And since the thread is bumped, I might as well answer a 3 year old question...

tabm0de wrote on 2017-02-07, 09:36:

Is there anyone that know where i could maybe find the copy of the recovery disk for Compaq Presario 433?

Someone uploaded this last year: https://archive.org/details/compaq425433filesmsdos62

How many memories that computer, I wish I still had it maybe I could have solved the problem. One thing it's incredible but still remember, after almost two decades when I found it and powered it again since the 1995, the smell that computer gives out from the crt opened case lines once the pc became warm, I can't say if equal to all the others all-in-ones, but I recognized that -immediately- the very same smell of that specific heated plastic/pcb/power supply or whatever that after twenty years. It was impossible to not notice because the computer is really compressed with its components heating.
I remember I couldn't believe it myself but I never noticed the same smell from others old computer/crt. I think someones said the smell is the most powerful memory "connector" of the human being and to me that surely was one positive test of that theory. 😁
Also the sound of the internal speaker. I remember when I started Stunts with PC speakers mode the tone of that speaker (more on the low frequencies tone side) was exactly as I remembered, at the end every pc speaker was different in every retro pc I tried and that was it, the right one. 😀

Last edited by 386SX on 2020-05-21, 13:35. Edited 1 time in total.

Reply 63 of 80, by Pierre32

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Hehe yeah 😀 I hear you on not wanting to open and close it too much too. It's the only computer I've owned that must be _fully_ re-assembled just to switch on. Break or cross-thread the two chassis screws and it's game over. Not to mention anything else going wrong when you slam it shut like a stiff drawer over and over. I had a mystery ESS sound card that needed some jumper experimentation, and that just wasn't viable to do in this machine. That's why I ended up getting the SB16 - a well documented card that I could install once then leave it alone!

Reply 64 of 80, by 386SX

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Pierre32 wrote on 2020-05-21, 13:30:

Hehe yeah 😀 I hear you on not wanting to open and close it too much too. It's the only computer I've owned that must be _fully_ re-assembled just to switch on. Break or cross-thread the two chassis screws and it's game over. Not to mention anything else going wrong when you slam it shut like a stiff drawer over and over. I had a mystery ESS sound card that needed some jumper experimentation, and that just wasn't viable to do in this machine. That's why I ended up getting the SB16 - a well documented card that I could install once then leave it alone!

Yeah I think the idea was good but the connection would have been made into a metal frame to be opened it as much as possible. Not to mention the proprietary connector at the end, the power supply powering also the CRT... if something get broken it become a serious problem inside there.
Once the choice of the components have been made/upgraded and you get to correctly close it (many times it didn't boot just for the connector at the end of the mainboard) leave it like that. 😀

Reply 68 of 80, by 386SX

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One thing I'd like to ask if someone studied where the 20MB limit is and if it'd be possible to go higher considering an Overdrive 100 would be possible I suppose, I certainly tried the 66Mhz years ago. But that limit looks like a marketing choice more than a hw limitation. Regarding the ram, I think to remember trying 30 different modules of every sizes and only to find some 4MB ones supported. At the end I found in a eletronic fair two modules of the same model that vertical rams on a side and horizontal on the other and that were supported for a total of that 20MB limit. Something I think would be considered is what happens if one of the soldered ram modules fails on the mainboard because I suppose that's what happened with my old Presario 425. In my 386SX I think adding ram did disable the on board ones, on that Presario I think that if the ram fails onboard, it may not boot no matter which rams you add. That was the only explanation I arrived to debug why it couldn't boot anymore.

Last edited by 386SX on 2020-05-22, 14:01. Edited 2 times in total.

Reply 69 of 80, by perhenden

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386SX wrote on 2020-05-22, 09:07:

considering an Overdrive 100 would be possible I suppose, I certainly tried the 66Mhz years ago. But that limit looks like a marketing choice more than a hw limitation.

I use a dx4 100 ODPR overdrive in mine. It runs a bit hot, but works.

Reply 70 of 80, by 386SX

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perhenden wrote on 2020-05-22, 13:27:
386SX wrote on 2020-05-22, 09:07:

considering an Overdrive 100 would be possible I suppose, I certainly tried the 66Mhz years ago. But that limit looks like a marketing choice more than a hw limitation.

I use a dx4 100 ODPR overdrive in mine. It runs a bit hot, but works.

I remember not having tried the DX4 Overdrive for that reason cause it runs already hot in a normal case, inside that I suppose temps would be too high so I'd need a fan and that wouldn't be a nice thing for a "time correct" sound of that pc. Maybe if I'd find a very silent low speed one to put on the original heatsink but I don't know about the space left above the cpu.

Reply 71 of 80, by perhenden

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386SX wrote on 2020-05-22, 13:58:

I remember not having tried the DX4 Overdrive for that reason cause it runs already hot in a normal case, inside that I suppose temps would be too high so I'd need a fan and that wouldn't be a nice thing for a "time correct" sound of that pc. Maybe if I'd find a very silent low speed one to put on the original heatsink but I don't know about the space left above the cpu.

That CPU can take hot, but it doesn't feel right to me, I would have to drill some venting holes I think, for it to be stable in warm environments.
My conclusion was that dx2/66 is the right max for this computer.

Reply 72 of 80, by assasincz

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386SX wrote on 2020-05-21, 14:39:

Man you will not believe it, I think I may have found one in a local store the 425 model in decent a bit yellow condition... 😁
Let's hope if still available.

I am curious, tell me more (Im from Czech Rep. though but still)...

Reply 73 of 80, by 386SX

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assasincz wrote on 2020-05-22, 15:00:

I am curious, tell me more (Im from Czech Rep. though but still)...

It's not new, in fact seems to need some restoration work and far from looking like the ones posted above, the local seller has its own since 1993 and now sell it so I may go to check and see it hoping to be again a new Presario owner soon. 😀

Last edited by 386SX on 2020-05-22, 20:11. Edited 1 time in total.

Reply 74 of 80, by 386SX

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perhenden wrote on 2020-05-22, 14:14:
386SX wrote on 2020-05-22, 13:58:

I remember not having tried the DX4 Overdrive for that reason cause it runs already hot in a normal case, inside that I suppose temps would be too high so I'd need a fan and that wouldn't be a nice thing for a "time correct" sound of that pc. Maybe if I'd find a very silent low speed one to put on the original heatsink but I don't know about the space left above the cpu.

That CPU can take hot, but it doesn't feel right to me, I would have to drill some venting holes I think, for it to be stable in warm environments.
My conclusion was that dx2/66 is the right max for this computer.

Exactly what I was thinking years ago. The Overdrive 100 with the voltage regulator get incredibly hot and maybe it was intended to be that way but still I'd not risk to break something also considering the power supply that has to power the CRT too.
Question: what about power supply? How to check the condition of the capacitors if its inside the monitor part of the case?

Reply 75 of 80, by Pierre32

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386SX wrote on 2020-05-22, 20:09:

Question: what about power supply? How to check the condition of the capacitors if its inside the monitor part of the case?

Not too hard to get in there for a visual inspection at least. Just four screws IIRC. Acutally replacing anything in there would start to get more interesting.

Don't forget the usual safety precautions when working around CRT internals of course!

Rust-Repair-5.jpg Case-Clean-3.jpg

Reply 76 of 80, by 386SX

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Pierre32 wrote on 2020-05-22, 21:44:
Not too hard to get in there for a visual inspection at least. Just four screws IIRC. Acutally replacing anything in there would […]
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386SX wrote on 2020-05-22, 20:09:

Question: what about power supply? How to check the condition of the capacitors if its inside the monitor part of the case?

Not too hard to get in there for a visual inspection at least. Just four screws IIRC. Acutally replacing anything in there would start to get more interesting.

Don't forget the usual safety precautions when working around CRT internals of course!

Rust-Repair-5.jpg Case-Clean-3.jpg

Thanks, Interesting. I always thought it'd be more difficult to get there. Is the main PSU build quality any good?

Reply 77 of 80, by Pierre32

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386SX wrote on 2020-05-23, 08:31:

Thanks, Interesting. I always thought it'd be more difficult to get there. Is the main PSU build quality any good?

I didn't investigate that closely. Mainly a quick clean, and made sure there wasn't a family of possums in there 😁

Reply 78 of 80, by 386SX

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Pierre32 wrote on 2020-05-23, 09:11:
386SX wrote on 2020-05-23, 08:31:

Thanks, Interesting. I always thought it'd be more difficult to get there. Is the main PSU build quality any good?

I didn't investigate that closely. Mainly a quick clean, and made sure there wasn't a family of possums in there 😁

Cause I've seen too many PSU with bad capacitors not to mention mainboards and now it's the first thing that come in mind when I buy mainboards, psu, video cards.. 😀

Reply 79 of 80, by assasincz

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I consider this a great coincidence, being able to source locally two 460s just a week apart. Second one (right) is in much better shape, with original floppy drive and brighter screen with no burn-in. Yeah, I am very happy now...

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