BitWrangler wrote on 2021-07-29, 01:48:

Hey gang,

What's the feels about 386/486 combo boards when you use them for 386es? Is it like "well done dumbass, you just crippled a 486" or like "Yeah but it's not really a 386." or "What's even the point when it takes a 486?"

I has me one, a 486LC1, contaq chipset, I has me many other 486 boards to run 486es, I has me soldered down 386SX25s for 386es. I see AMD 386DX40s, I think them shiny.

I had an Acer VI9, but ended up selling it to friend for his 486 retro project. I did not see much value in it either.

BitWrangler wrote on 2021-07-29, 01:48:

I has me one, a 486LC1, contaq chipset, I has me many other 486 boards to run 486es, I has me soldered down 386SX25s for 386es. I see AMD 386DX40s, I think them shiny.

Not sure exactly when those boards were released, but I'd guess the Am386DX-40 is the whole reason they exist. Perhaps it was uncertain when the Am486 would get released due to all the legal issues, and 386/486 boards had the biggest market?

I have an OPTi-495SLC that I use for a 386DX-33. Why? Because I already have enough good 486 only motherboards.

There is a nice brochure of it in this tread: OPTi-495SLC & 386DX-33

I've got a system with 386/486 mobo. The original owner bought the system with a Texas Instruments 486DLC33 in it then later upgraded to a 486DX2/66. When I bought the system I got the 486DLC cpu as well as his Dos/win3.1 disks and some other applications.

pan069 wrote on 2021-07-29, 02:49:

I have an OPTi-495SLC that I use for a 386DX-33. Why? Because I already have enough good 486 only motherboards.

There is a nice brochure of it in this tread: OPTi-495SLC & 386DX-33

Funny you mentioned that :

jakethompson1 wrote on 2021-07-29, 02:43:

Not sure exactly when those boards were released, but I'd guess the Am386DX-40 is the whole reason they exist. Perhaps it was uncertain when the Am486 would get released due to all the legal issues, and 386/486 boards had the biggest market?

Would seem like it, get a board with a cheapo 386 in it now, get a 486 when they drop below $300 or something. Or for "walking" upgrades, like you could move your current CPU to a potentially faster board (if you had an early DX board and were maybe crippled by umpteen wait states on your full AT acre of 100ns discrete RAM) Kind of a thing through the years, you could find boards that let you move your P75 and SIMMs to a super-ish socket 7, and get 400Mhz and SDRAM later... or move your Duron and SDRAM to a K7S5A and pimp it out with an XP2100 and DDR next year, or move your AM2+ X2 CPU to an AM3 board and end up with an FX8x00... it was kinda like that I was still using my "original" IBM XT in 2003, "Triggers Broom" style, it had had 4 new motherboards 5 new CPUs, 2 new cases and 6 HDDs, but it was still my original IBM XT, see, there's the FRU tag on the speaker to prove it. (I actually moved that thing for a number of upgrades, then lost track of it, derp.)

These boards were mainly about the Cyrix DLC and Am386DX-40

At the time Intel charged insane amounts for the i486, even the i486SX, and the added value of the early 486 chips over the much cheaper 386 and 486DLC options was limited. However the added value of local buses (OPTi and VESA) over ISA was clear. So you got these boards that let you combine a cheaper CPU with similar performance with a fast VLB setup for video and I/O. The 486 socket was just an afterthought to allow a theoretical upgrade path.

You can see the evolution based on price of 486 on some 386/486 boards. Earliest revisions only had PCB silkscreen for 486, later versions had both sockets implemented and finally (once 486 became affordable and DX/2 appeared with compelling speed advantages) the 386 socket was left out. For good measure there were also boards with surface mounted Am386DX-40 or i486SX alongside the other socket.

Usually hybrid boards have VLB and that is pretty nice for 386. It doesn't matter much in raw performance, but you can get a decent VLB VGA card with Windows acceleration. And this improves the Windows experience on a 386 very much.

Otherwise I like these boards to play around with different PGA132 processors and VLB cards.