Menu:
Built in DECs Taiwan facility, the DECpc 325sx LP was introduced in April 1992
starting at S$2,599 or AU$2,660 with a 14" monitor, DOS 5.0 and Windows 3.0 included.
I can find no reliable reference to it being sold outside the Asia-Pacific region.
Most sources place the introduction of the DECpc LP line of computers as August or November 1992. And the August 1992 product announcement only mentions one 386SX - a 33MHz model. And yet this page is about 20Mhz and 25MHz 386SX models. Machines built in April 1992 no less - four months before the well known DECpc LP models were announced. And at the time this page was written (28 January 2024) a Google search for "DECpc 325sx LP" returns only nine (9) results. Searching for "DECpc 325sxLP" (how it appears on the front of the machine) returns only four results - three of them me! The 320sx model returns even fewer results. Googles usenet archives don't turn up much more either.
I do have a copy of the manual for the DECpc 333sxLP mentioned in that August 1992
announcement. And to confuse matters further, that manual (ER-PC733-UA.A01) is titled
DECpc 325/333 sxLP Users Guide. But the
computers this manual describes have
Cirrus Logic CL-GD5422 graphics hardware and the machines this page is about have
Oak OTI-067 graphics. So there appears to be two different versions of the DECpc 325sxLP.
The older DECpc 325sxLP, and the DECpc 320sxLP, are correctly described by EK-DECSX-UG.003 DECpc 320sxLP/325sxLP User's Guide and EK-DECSX-TM.001 DECpc 320sxLP/325sxLP Technical Reference Manual. The only other mention of these machines, besides stuff I've written, are an advertisement in a Singaporean newspaper and an article in an Australian one, both from April '92.
This article from August 1992 mentions at the end that DEC was testing their new PC strategy in the Pacific Rim region in early 1992 successfully selling 2,000 machines to the Hong Kong Stock Exchange. And this usenet post from June 1992 also mentions the Hong Kong Stock Exchange buying a number of the "newly announced DECpc 325sx LP workstations".
So it seems DEC was testing the market for a new line of PCs in the Asia-Pacific region in early 1992, and it seems likely that's what we have here. If these two models introduced in April 1992 were only sold briefly in the Asia-Pacific region it would certainly explain why there are so few references to them online in 2024.
It would be interesting to get photos (or even better, physical examples) of the DECpc 325sxLP and 333sxLP models introduced in August 1992 to compare with.
Press Ctrl+Alt+S to enter the BIOS. It's not obvious, and the BIOS doesn't tell you what to press or when. The users guide does, but part of the page containing this information is cut off in the scanned version available online making figuring out what to press a bit challenging.
The Singaporean Advertisement states that these shipped with DOS 5.0 and Windows 3.0. Given Windows 3.1 came out the same month I expect DEC would have moved to Windows 3.1 before long.
And I have a copy of DECpc Windows 3.1 from around the time these machines were sold. I believe the disks
originally came with a DECpc 333sxLP from around September 1992, but the SPD document (37.30.00) is dated
April '92 and the disks are no older than June '92.
The subsequent SPD revision (37.30.01) from September '92 drops mention of DECs DOS customisations and the
DOS HELP! disk implying that perhaps DEC switched to shipping unmodified MS-DOS 5.0 around that time.
These disks include the graphics drivers for both the Oak OTI-067 chip in the DECpc 320sxLP/325sxLP and the Appian graphics board in the DECpc 433 Workstation, along with drivers for a selection of DEC printers. The MS-DOS installer will ask for four disks (the fourth being the DOS 5.0 HELP! disk) and will install a handful of generic DEC utilities. The Supplemental Drivers disk mostly consists of Windows 3.0 printer drivers.
Included documentation is:
And the disks are:
Graphics drivers for the integrated Oak OTI-067 are included in the version of Windows 3.1 linked above - at the blue Windows Setup screen where it lists your computers configuration, head up to Display and pick one of the Oak VGA drivers. If you've already got Windows 3.1 installed, drivers are linked down the bottom of the page.
In my testing Oak VGA 640x480 256 colors (286 or better) gave an annoyingly large font size. I found performance to be fairly poor with the Oak drivers too - you could see window backgrounds fill. I ended up just switching back to the standard VGA driver.
These machines originally shipped with a Rayovac 840 4.5V alkaline battery
attached to the motherboard next to the power connector with Velcro. This battery will leak eventually
and cause serious damage, so it must be removed on sight. Normally these batteries aren't such a problem as
they're typically attached to some part of the case. But a DECpc they're no better than the infamous Varta:
I've replaced the battery in my working machine with three Energizer Ultimate Lithium cells. These are guaranteed never to leak (time will tell I guess) and supposed to have a long shelf life. These batteries actually have an open circuit voltage of 1.8V putting three of them at around 5.4V - quite a bit higher than the original battery.
In this machine the battery is connected to the VBATT pin on the 82C331 ISA bus controller through a diode (D6) that has a voltage drop of 0.56V. This means that with a 5.4V battery you end up with around 4.8V at the VBATT pin. The datasheet for the 82C331 says the allowed range for VBATT is 2.4-5.25V, so I'm satisfied this is safe.
Thanks to the diode, connecting the battery the wrong way round won't damage anything, but it also won't work.
The battery plugs in to J8 with the positive pin being the one nearest the IDE connector. The pin at the
pin the opposite end is negative.
Like the later DECpc LP series, the power switch is inside the power supply. The button on the front
of the computer is connected via a linkage to the power supply switch with a short rubber tube that fits over
the end of the linkage and the switch to keep them aligned. On every machine with this setup I've encountered
the tube has disintegrated leaving the end of the linkage floating unaligned with the power switch. This
results in the button on the front of the machine not working.
My solution so far has just been to make a replacement tube by rolling up a small bit of paper and wrapping a
bit of sticky tape around the outside. It's not an ideal solution but it works ok.
You can use either 4MB or 16MB 36bit SIMMs in pairs starting in bank 0. If you're mixing 1MB and 4MB SIMMs, the 1MB SIMMs must be installed first
Is limited. Hard disk type 48 will let you enter the CHS values yourself but there is no LBA support. I've not tested CF cards with this machine, but the DECpc LPv/LPv+ are known to have issues with them and I doubt this much older model is any different. Probably best to use an XT-IDE ROM if you want large drive or CF card support.
| Name | Model | RAM | CPU | HDD | CD-ROM | Cards | Condition/notes |
|---|---|---|---|---|---|---|---|
| 325sxLP | 16MB | SX-25 | Quantum ProDrive LPS: 52MB (OEM drive) 105MB |
— | Digital DE200 network Creative SoundBlaster ViBRA 16S CT2900 |
Working 30/01/2024, hard disks unreliable (don't always come ready unless the machine has been off a while). Battery replaced 30/01/2024 (3x Lithium AA). Riser with blown tantalum cap replaced with riser from other machine 30/01/2024. Built 14 April 1992. Model number sticker missing. PhoenixBIOS A386 Version 1.01. DECpc 325sxLP Version 1.11. |
|
| 325sxLP | — | SX-25 | — | — | — | Severe battery damage, possibly irreparable. No drives, no cards, no RAM, no 5.25" blank,
no hard disk bracket. Tantalum capacitor C3 on riser board has blown (failed 29-SEP-2021 in the other machine) Built 6 April 1992. Model PC731. |
