First post, by rkurbatov
My first PC was Am486DX4-100 that was bought in 1997 - very interesting time, when you could choose from several generations of PC being very different. The friend of mine was happy to play Dune II on his 286, retired from some office, another friend of mine did his university labs on 8086 and third friend of mine (very rich one, I suppose) was playing games on Pentium MMX while PII was on horizon.
So my PC was quasi-Pentium, based on Sis496 chip with PCI slots, probably even supporting EDO memory, with notebook HDD put to it for some reason (I knew that much later, because I was afraid to open it for several years 😀). I missed the VLB stuff completely, like SCSI and SIMM modules, all my adapters were Plug and Play so I wanted to play with something more 486ish when I planned this build initially.
I wanted to build classic 486 DX2 66MHz on VLB motherboard. And this journey turned into pain and still too far from resolution 😀
It's not interesting to get something prebuilt (though I payed probably twice or triple from that price already - enough to buy a new average machine), so I started hunting for parts last year, long before the war.
The motherboard is ECS UMV486V AIO
Seems not damaged because of external battery. I had to add one created from CR2032 holder and PC Speaker connector.
There was a problem with RAM modules when I was trying to install 8x1MB. I tried 3 chip modules in two sets, absolutely the same, but motherboard saw only 4MB of RAM for some reason. Like I install each of set independently and see 4MB and install them both - and again, see 4MB. The problem solved when I took another set of 1MB modules (with 9 chips) but later I found 8x4MB modules so now I have 32MB in total. I would have killed for such amount a memory back those days - I had only 8MB - barely enough to use WIndows 95.
Also need to check how turbo implemented on it. The mobo is not extendable, DX4-100 will not work in it, as it supports 5V CPUs only. I'll need a voltage regulator. There are known problems with WB cache and non-working motherboard cache in case AM5x86 CPUs are used. Pentium Overdrive is to rare (and I'm going to build pure Pentium build anyway).
I put motherboard in horizontal desktop case:
Nothing remarkable about it, I just wanted it to be non-tower one. Still don't know what S/B button does.
The videoadapter is Trident TGUI9440AGi
It was 1MB initially, but I managed to find memory chips so now it's 2MB.
There is a problem with it I noticed recently, when started working on build on a regular basis. When I turn the PC on, I can have broken image in text mode, like lots of garbage in video memory. Usually, when I turn it off and on again, the problem disappears. I will try running it on 1MB of original memory and see if it helps. I have two spare modules to replace. Or maybe it's something related to capacitors, I don't know.
The motherboard has almost everything on it - two COM ports, LPT, gameport and FDC/IDE controller so I don't need a multicard.
The soundcard is ProAudio Spectrum 16. All I knew about it before - it's the strange name I saw in games setup program 😀
My card is with LMSI controller on board, this exact one:
$40 in prices before war 😀 Probably, only few are in Ukraine, only GUS is more rare one.
The network card is 3COM EtherLink III:
A good source of EPROM for XT-IDE Bios, has to be configured via the special tool to make XT-IDE work as it doesn't have jumpers.
XT-IDE is veeery convenient thing (and not only for IDE drives). I have two floppies - 5.25 and 3.5 - and due to the case shape the only way to connect them is when 5.25 becomes the drive A. And DOS boots only from drive A.
I wanted to make my own cable and bought everything for it but eventually found the cable of required lenght in one of the cases I bought recently. There are several solutions for my problem:
1. Twist the cable again close to the FDC end (I will probably do that when will create custom cable, don't want to do something with existing one)
2. Make an adapter with a twist (I need the male 40 pin connector for that, too problematic)
3. Install XT-IDE that allows drive swapping on old BIOSes - that's what I did.
The harddrive was the real pain, the most problematic part.
I could have used the CF-adapter, but I wanted the real hard drive so wanted to play with SCSI. I was hunting for the VLB SCSI for a long time, until found the Adaptec2842A:
First, I spent a day trying to make it run at all. The problem was in a small jumper enabling the WB-cache (the motherboard doesn't support it).
Second, I tried to add support for larger hard drives. I used 18GB SCSI (68 pin via 68 to 50 pin adapter). There was an Adaptec BIOS patch by mkarcher (thanks him a lot), but I had different BIOS version so had to make my own patch with offsets of my BIOS based on his work.
And when I had all of it working and partitioned my hard drive it died 🙁 The problem with SCSI is that there are many hard drives with SCA-80 interfaces, even the new ones, of size 73GB or more that don't work on old 50-pin adapters. The simply don't have narrow/wide switch so SCA-80 to 50 pin adapters simply don't work. I bought 2 18GB drive with HD68 - one was dead initially and another one died few days ago - the motor tries to start and squeaks, though adapter detects the hard drive. The same was with 9GB drives.
The optical drive is period correct 6x CDROM Toshiba XM-6002. I managed to find drivers (all CD ROMs with speed up to 16x are very hard to make them work, they all require specific drivers, common ones simply don't work - sometimes every model has its own driver) but it had mechanical problems. I fixed mechanical problems by applying grease - it stopped to be recognized by the system. I need to check now whether it's IDE cable problem, drive or controller - HDC behaves quite strange on this motherboard.
So my initial plan to assemble everything during this short vacation wasn't completed. The battle rages on.
Anyway, it's interesting journey! I learnt how to program chips, knew a lot about their difference and how device BIOSes work. Experimented with different SCSI adaptors. Hope I will play Lotus III till the end of the year on my new old machine 😀
Attachments
486: ECS UM486 VLB, 256kb cache, i486 DX2/66, 8MB RAM, Trident TGUI9440AGi VLB 1MB, Pro Audio Spectrum 16, FDD 3.5, ZIP 100 ATA
PII: Asus P2B, Pentium II 400MHz, 512MB RAM, Trident 9750 AGP 4MB, Voodoo2 SLI, MonsterSound MX300
