My Presario 425 uses a 486 dx4-100 ODPR - it is hot, but that should be within specs for that CPU. The ODPR variant regulates the current so that it becomes the expected higher voltage number.

Is it possible it's for added cache? I got a similar slot on a socket 7 motherboard that adds cache to the motherboard. I have a Presario 425 with this slot as well and would love to discover what its purpose is!

I've been tinkering with my 486 DOS-machine, setting IRQs and loading drivers to make sure the soundcard and the network card both load. Preparing for DOS TCP networking support, with SFTP, and possibly SMB.

Thanks, I just sent the request, and included my username. I've not yet accumulated enough points/posts to send PM .

(Don't know where else to ask) I'd like to register for a new account on vogonswiki.com, to add some information, but it fails with an error. "Error sending mail: authentication failure [SMTP: Invalid response code received from server (code: 535, response: 5.7.0 Authentication failed)] " Who should …

mdog69 wrote on 2020-04-17, 06:46: I've got a spare 3C503 which works in 8bit slots... Thanks for offering, I'll keep that in mind.

Thanks, a 16-bit ISA card that works in 8-bit slots sounds good. The Intel EtherExpress ones are affordable on eBay. In addition to RTL8019-based cards, I read that 3Com 3c509 (not B-revision) are 8-bit compatible. A good list of compatible cards here https://www.vogonswiki.com/index.php/Property:Is …

I'd like to connect my old Amstrad PC1640 to the network, for easier file transfers. An 8-bit Etherlink II would be my first choice, but they are rare and expensive. Are there any modern options, like a serial or LPT adapter for Ethernet TP-cable/RJ45, that also works in DOS? Would like to avoid …

I bought an old 486! A Compaq Presario 425. 486 sx 25 Mhz, 12 MB ram, 107 MB hard drive, 0.5MB video ram :) It boots OK, all the hardware looks to be working. I've cleaned it up. Now, it's time to get files in and out of it. My initial plan of using an IDE-USB adapter to read the IDE-drive from my …

computerguy08 wrote on 2020-04-15, 15:36: How modern is your computer? It's a B450 motherboard, so more recent than x58. Good to know that somewhat recent motherboards (with x58 or earlier chipsets) has IDE-support, though 😀

How can I read IDE drives of sizes 540MB and below on a modern computer? I tried an USB-adapter, but it only supports LBA, not the older CHS style drives. Some old drives may also lack auto detect, I read. Some internal adapters also lack the ability to read CHS drives, I read. The drive I'm working …

What is the manufacture and model of your motherboard This is a Compaq Presario 425 mother board. If you disable the original chip somehow then you can use any chip in the overdrive socket. It doesn't have to be overdrive model. Nice! There are jumpers to disable the on-board CPU, for when using …

My 486 motherboard has a non-removable 486 sx-25 chip, and an empty overdrive socket (socket 1). The best choice would be to get hold of an overdrive CPU, and insert it into the empty, waiting socket. To save money I would like to use a 486 DX2-66 CPU available to me for the upgrade. The motherboard …

Oh, I took "new" to mean manufactured recently, but it is marketing speak for "old, but never used" 😀 This explains why the manufacturer doesn't have a web presence! +1 to authenticity for my build then, on the plus side.

An addition: There's an 8-bit ISA adlib clone on ebay, manufactured by "Sun, Moon, Star", described as "VINTAGE NEW ADLIB 8 BIT ISA SOUND CARD WITH SPEAKER OUT AND VOLUME CONTROL". I bought it and it looks ok. Source: https://www.ebay.co.uk/itm/VINTAGE-NEW-ADLIB-8-BIT-ISA-SOUND-CARD-WITH-SPEAKER-OUT …

Thanks! I found that MS-DOS 3.2 and Dos plus 1.x, which the PC1640 installation media contains, supports drives up to 32MB . Later versions support larger drives/partitions, up to 2GB, with FreeDos having a theoretical limit of 2TB (!). I learned that the original CHS addressing (on IBM PC) is using …

The harddrive in my old PC1640 needs replacement, and I'm not sure which CF cards will work with the CompactFlash adapter for XT-IDE I bought. My guess is that large cards , above 32MB and UDMA-enabled cards will not work. New/long-life cards within those specs may be hard to find or expensive. …