Compaq Prolinea 4/25s Build

I'm sure a build thread is nothing new to you guys. I feel like documenting things as I go just for the fun of it and I thought it may at some point be of some use to others. Nothing extreme will go on here, just your standard hardware upgrades, and later, software installs. Here's the rundown...

I recently purchased a Compaq ProLinea 4/25s. What I know about it so far (I'm waiting for shipment) is:

486/25mhz processor (I think that makes is a 486SX)
4MB RAM
2.5GB Hard Drive
3.5" Floppy Drive
5.25" Floppy Drive

It's apparently pretty clean, boots to a DOS 6.22 prompt. I still feel like I paid too much, but I haven't had any luck finding anything local and this was one of the cheaper ones on ebay. I paid $68 shipped to me.

I've wanted a 486 for a while to mess around with. I want to put Win 3.11 or Win 95 on it (hell, maybe both) and play some old games and just mess with it. Another big plus and probably the primary reason I wanted it was because it has both the 3.5" and 5.25" floppy drives and I have an IBM 5150 that will benefit from that.

So, what do I want to do? Well, nothing fancy, really.

- Upgrade to the max RAM, which I believe is 56MB (odd number, I know) I think this one will have 4MB soldered on the board and 4 slots. You apparently MUST have a "Compaq Approved" 4MB 70ns SIMM in the first slot or it won't read any extra memory. So, 8MB and 3 slots loaded with 16MB SIMM's.

- I want to look further into the possibility of upgrading the processor, and I kinda hope that someone may already be able to answer that for me. I'd like to put a DX2 in it if it would be worth the trouble. 486 processors aren't soldered on to the boards, are they? I seem to recall coming across old machines when I first became a PC Tech (like 10 years ago) that had irreplaceable chips on them. Hard to tell from the only pic I could find.

- Put a network card in it. This should be fun.. the process will be transfer games from my main pc to the ProLinea where it can then be copied to a 5.25" disk for use on the 5150.

- Put a sound card in. Must have since I'm going to be retro gaming on it. Or wait.. I guess a lot still used the PC speaker, huh?

Compaq Prolinea 3 and 4 Hardware Guide - Here's a handy Hardware Guide I found. I put it up on my own web server, never know when that link may become unavailable.

Here's what it looks like (ebay pic):


Aside from cleaning it up and doing some experimentation with OS's, that's all I really have planned for now.

Unfortunately, I can't be sure on all my hardware till it gets here. In the meantime, tell me what you think.. or give me some ideas

Thanks!
Kirk

486DX25's were sold when the 486 first came out so it might not be an SX.
No idea what you can upgrade the CPU to, most likely a Kingston 486/133 would work.

Threads like these always end up being useful to somebody, especially when you've got some hardware with some strange quirks, like Compaq 486s often do.

Regarding the price, if you're willing to hold out for long enough, systems like this will come up very inexpensively, but "long enough" could mean weeks or it could mean years, depending on your luck. The last time I checked the going rate for a big name-brand 486 (Compaq, IBM or Dell), they were going for anywhere from $60-$70 shipped, so you did OK.

A machine capable of running Windows 95 with a network card and a 5.25" drive is invaluable for transferring data to other vintage machines, so I think that upgrade plan is very prudent. And you can run early Win95 titles on the machine too.

Regarding the memory, many of the low-profile Compaq 486s would only take a 4 MB SIMM in their first slot, but up to 16 MB in the other three. I had a Presario 660 that had exactly the same memory configuration as your Prolinea 425. On my Presario 660, that SIMM didn't have to be anything special. Mine had either an Acer or a PNY 4 MB SIMM in the first slot.

Some of those low-profile Compaqs can be goofy regarding CPU upgrades. I've never tried to put a CPU upgrade in a Prolinea 425, but when I put a Kingston Turbochip (with a 133 MHz AMD CPU on it) in my Presario 660, it behaved exactly like a DX2-66. The only way to know for sure what your CPU situation is will be to open it up and look inside. Some 486SX systems had a soldered-on 486SX CPU with a 487 upgrade socket, which limited your upgrade options somewhat, and others had the CPU in a regular 486 socket so you could replace them with something faster.

I do think, given the model number on the case, you probably have a 486SX. Usually if they included an "s" in the model number, it was an SX. But, since it has a 2.5 GB HDD in it, there's the outside chance that a previous owner upgraded the CPU too. Given that it only has 4 MB of RAM in it, someone harvested any memory upgrades it might have come with, but when SX25s were new, the mainstream hard drive size was around 170 MB.

You might consider replacing the hard drive with a CF-IDE adapter and a 4 GB CF card. It'll be faster, quieter, and more reliable. Depending on the BIOS, you may need drive overlay software to use a 4 GB drive.

I spent way too much time in college playing DOS games on systems very similar to this one, so I think you've got a nice find there.

I've owned two Compaq ProLinea Net/25 machines...these have an integrated CRT a la compact Mac/IBM EduQuest and a proprietary NIC expansion slot. They had a soldered 486SX-25, but also had an "upgrade socket" which allowed you to plug in a 486DX2-66. IIRC, it just disabled the soldered processor. RAM was 4 MB onboard with two 72-pin SIMM slots. I upgraded one of mine to 20 MB, and I'm almost certain the RAM used wasn't Compaq-branded RAM. You do need to make sure the SIMMs you choose are compatible with the motherboard, though (timing, EDO vs FP, et c.)

I have 2 machines like this, but dx2/66. One is overdrive compatible (socket 2) (4/66). Other is socket 1 or perhaps 0? (4/33s)

Somehow mine dont need a 4mb stick in slot 1, that definitely is weird. I do know they will not usually tolerate double sided ram. Perhaps thats why you have issues with bank 1? One difference is mine have Sx/33s not Sx/25s soldered on board. At least the integrated video is pretty decent! Tseng et4000. :D I also have a IBM Valupoint board that fits into the same chassis!

I be willing to scrap one for the mobo if you wanted, due to one having a pretty sad looking case. Only thing I dont like about them are the rail system. Somehow over the years I lost the rails for the 5.25 bays...

As to the first bank RAM troubles, if the desktop version is like the All-in-One version, then it has 4 MB RAM soldered to the motherboard, which can't be disabled.

Mine also have ram 4/8mb soldered, but when a stick is on bank 1, it gets disabled. I know this as true because on one has 4 16mb simms with 64mb detected. On the other I notice there is no simm on slot 1. Hrmmmm...

Yeah, after doing some searching I am pretty sure this is the board that will be in my system:



From what I can tell it is soldered on and there is a lack of an upgrade socket.

It's not a big deal. I am really not sure what the speed difference is between 25 and 66 mhz. As long as I can play Wolfenstein, Doom, Descent, Some older Ultima games (hopefully up to Ultima 7) then I'll be ok with the SX processor.

Computer just shipped today. It's coming ground.. I don't recall from where.. but it's scheduled delivery date is the 11th. Oh, great, I hate waiting

Well done.

Will just an 'any old' IDE to CF car adaptor work on this thing or do I need to look for something specific?

twolazy said:

Mine also have ram 4/8mb soldered, but when a stick is on bank 1, it gets disabled. I know this as true because on one has 4 16mb simms with 64mb detected. On the other I notice there is no simm on slot 1. Hrmmmm...

Click to expand...

That's good to know. Could be bank 1 doesn't *have* to be used. Nice to know some of these boards can go to 64MB though. If you want to run Win95, that extra memory is nice to have.

abigbadzebra said:

From what I can tell it is soldered on and there is a lack of an upgrade socket.

Click to expand...

That's a socketed 486 in the picture. The soldered 486s look different. The empty spot above the CPU is where a soldered processor would go. So you should be able to put a DX2/66 in it, if that ends up being the board you get.

abigbadzebra said:

Will just an 'any old' IDE to CF car adaptor work on this thing or do I need to look for something specific?

Click to expand...

You shouldn't need anything special. Any CF-IDE adapter ought to be able to handle the PIO modes that a 486 board will have.

Ok dug out the related machines... Both have sockets btw. One looks identical to your picture, with an sx/33 in place. Other is a dx/2 66. You will have 25/33 mhz bus selection. Now here's where it differs. One board has 4 or 8 mb onboard. The other does not! This explains why it was upgraded to 64mb. I can take pictures if you want... I also seem to have extra compaq simms here. :thumbsup:

abigbadzebra said:

Will just an 'any old' IDE to CF car adaptor work on this thing or do I need to look for something specific?

Click to expand...

Make sure you get the type that attaches to the end of a ribbon cable, and not the type that plugs directly into the motherboard. You'll find that there's not enough height to support the direct-into-the-motherboard type.

Paul.

paul.brett said:

Make sure you get the type that attaches to the end of a ribbon cable, and not the type that plugs directly into the motherboard. You'll find that there's not enough height to support the direct-into-the-motherboard type.

Paul.

Click to expand...

I second that, Compaq's are usually too low profile/crammed tight to pull off those direct to motherboard CF>IDE adapters. Usually plenty of room for those in AT style cases though, so there are uses for them.

I just tried with a direct CF to IDE adapter, one that plugs into the ide port on the motherboard. Fit and booted fine... about 1/2" from the top of the case. Its a tight fit, but theres more then enough room.

I appreciate the replies guys. Unfortunately I'm still waiting on the machine to arrive. It should be here Monday and then I can inspect the hardware closer.

I plan to get a IDE to CF reader and I'm also keeping my eye out for a parallel zip 100 drive.. mostly cause I have a couple 100MB disks from years ago that I'm curious to see the contents. I'm not going to buy memory until I have a chance to look at the board.

Thanks!

Kirk

I actually do have a question about the IDE to CF card reader. I see that there are both powered (4 pin floppy molex connector) and non-powered readers. Does someone know what I will need?

Thanks!

All compact flash adapters are going to require power when plugged into a standard 40 pin IDE connector. The ones intended to work with a 2.5" (44 pin) laptop drive don't require a power connector, because the 44 pin connector supplies power as well. But normal IDE controllers do NOT supply power.

There are some variants of IDE that spec a 5V power on one of the unused pins, however, and there are some industrial flash drives that use that. But the Compaq isn't going to support that.

-Ian

I knew that

Thanks

Alright, so I was almost correct about the board. This one has the 486SX processor soldered on with the socket open ready for an upgrade. Woot! Actually, this pic I took tells me almost all I need to know about the hardware and upgrade options.


So looks like I can throw a DX2 on there. Also, this board does require that a 4MB SIMM be placed in the first memory slot. So I just got one on ebay.


Came with a 9.6k modem.. lol.

Just a wide shot of the board


I got a 3com Etherlink 3 coming in the mail tomorrow. Still don't have floppies or a usb floppy for my main computer though, so I guess installation of an OS is going to have to wait. Actually, my IDE to CF adapter may come in the mail tomorrow also. I wonder if there is a way for me to pull off an install directly from it if I transfer the necessary files over first...