First post, by NJRoadfan
I figured I'd post this here since this is where the 486 gurus all hang out.
About a month ago I got an itch to do a 486 build, but with a bus I never really encountered in my years of doing computer repair. I never had an EISA system, so some horse trading on ebay and digging the bins at the computer shop I used to work at (and my basement) yielded the following thus far:
-Micronics EISA2-VL Full-AT motherboard with 40MB RAM, 256k L2 cache, and a 486DX2/66
-Jaton VL41 S3 805 VLB Video with 2MB VRAM (my #9 GXE64 somehow fried itself tonight! 😠 )
-SIIG ISA "EIDE" I/O card with enhanced BIOS. The MB has onboard I/O, but only 16545 UART and PS/2 mode parallel.
-Random 600MB Seagate HD and some 32X Mitsumi CD-ROM
-Adaptec AHA-2740W EISA SCSI
-3Com 3c597TX 10/100 EISA ethernet. Picked this one up for $6 on amazon, NOS! Much faster then the 3c509B ISA card I had in there.
-Soundblaster AWE32 CT2760 (NOT Rev 3! Still requires Diagnose to "soft config" it though)
-All housed in a period correct full AT case I had to take completely apart to squeeze the MB in!
On the way:
-Intel 486 DX4/100 Overdrive 5v
-Promise EIDE2300plus
I was going to use my Promise EIDEMax II paired with a Boca VL2 I/O card, but the I/O card and the motherboard didn't get along at all. that same card gave me problems on my Soyo SY-25N Socket 3 board, so its likely bad. The ISA card isn't horrible, it does support PIO4/MWDMA2. The motherboard is far from ideal in terms of stupid stuff, but I'll live with it.
Pros:
-Micronics makes quality stuff
-Has full EISA implementation with Intel chips and 2 busmastering VLBus slots. None of that HiNT crap!
-Takes 72pin SIMMs
-Supports AMD 5x86 and POD83Mhz (with limitations below)
-EISA CFG and tools easy to find
Cons:
-Has cruddy Phoenix BIOS
-Memory is configured with DIP switches, 64MB max.
-BIOS shadowing can't be enabled with more then 16MB of RAM. Memory count on boot is SLOW with it off. I have to use EMM386 to do shadowing in DOS.
-L1 and L2 cache is write through only. Major bummer
-5v Socket 2, need voltage adapter or overdrive/upgrade chips. (Soyo board even though its Socket 3, is a cheap model with the 3.3v VRM missing)
-No on board APM like my Soyo has. Did any EISA boards actually support that? I know the AIR 486EI was made into 1994.
-Only makes available 637k of conventional memory in DOS. Don't know if this is an EISA thing.
Despite the above, its proving to be a speedy little box. I wish my 864 card didn't die on me. I don't think the 805 is as fast, but it works in just about every OS I have used, including NT 3.1. I could always pull out the infamous Diamond Viper VLB (MIB) if I want a headache though. The most annoying thing is that my Transcend x133 8GB CF card refuses to run in any DMA mode with the SIIG card. Its stuck on PIO4, while that crappy Seagate runs on Multiword DMA2! I'll likely pick up a nice 9.1GB SCSI HD and avoid the whole mess.
Oh, and pictures will be coming soon.