Yeah I was gonna say, you should try to at least have 16mb ram for the beefier Dos titles that the box could run otherwise. Otherwise everything else looks pretty solid.

A very nice system you have there!

I wonder if the 486SV2 is compatible with the 486SV2G. I upgraded the BIOS on my 486SV2G (new BIOS date 11/03/95) and it added LBA mode for large hard drives, among other things. A cursory glance on stason.org shows they are very similar, with 2x VLB and the same SIS chipset although the TAG RAM chip is in a different place, the SV2 has 30 pin SIMMs while the SV2G has 72 PIN SIMMs, and the SV2 has solder pads for a PQFP CPU. Still, I wonder if the newer BIOS may work, it may be worth a shot.

Cool, can we have some pictures? I like to see what old cases people come up with.

The DX266 is such a great chip, perfect for 1994 era games. With regard to that Diamond Stealth 24 - how does it look? Using 3dbench I determined that it's the fastest of the VLB cards I have (compared to a Tseng ET4000AX and a Cirrus Logic GD5428), but it looks a bit washed out. The ET4000AX looks the best but was the slowest and was a bit glitchy in Keen4, so I've settled for the GD5428 with 2mb RAM.

I had an SV2, it died a horrible battery acid death. I was very cut when that happened, it was a superb board. I still have it, actually, it might be salvageable.

Good build dude, just one question:

"Roland MIF-IPC-A & MPU-401"

Does that mean you have two MIDI interfaces installed? What do you have connected to it/them?

SquallStrife wrote:

I had an SV2, it died a horrible battery acid death. I was very cut when that happened, it was a superb board. I still have it, […]
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I had an SV2, it died a horrible battery acid death. I was very cut when that happened, it was a superb board. I still have it, actually, it might be salvageable.

Good build dude, just one question:

"Roland MIF-IPC-A & MPU-401"

Does that mean you have two MIDI interfaces installed? What do you have connected to it/them?

The Roland MPU-401 is the interface in an external box and can be used with multiple systems, including an Apple II and Commodore 64. It is the on the left side of the image. The MIF-IPC/MIF-IPC-A is simple board with glue logic to place the interface on the ISA bus. A DB-25 pin cable connects the two. To this interface I can connect an Roland MT-32 rev. 0 or CM-32L and an SC-55. Until I sell/trade them, I also can connect a Yamaha FB-01 or SC-55ST.

Ah, you were being nice and specific. I don't know why, but I was imagining an MIF-IPC with the breakout box implied, and then some other non-Roland brand MPU-401 type interface, like a Midiman or whatever.

Great build anyway!

I may need faster cache to make the machine run reliably without a wait state. The 486DX/2 66MHz has a cycle time of 15ns. Memory accesses must respond to the CPU in one clock cycle or wait states need to be inserted. With 15ns cache, there would be no problem with running it without wait states. With 20ns cache, assuming it could go no higher, a wait state would need to be inserted. I will try it with the 0W/S and I get crashes then I will dial it back or buy faster S-RAM chips.

One thing I forgot to mention is that this system scales remarkably well. Using Trixter's TOPBENCH program, I can get overall speeds from 14 (IBM AT 8MHz speeds, all speed options off) to 210 (all speed options on).

Speed options include the Turbo button, 25/33/40MHz clock speed selection, Video and BIOS ROM caching, DRAM Speed of slow and fast, Cache wait state of 0 or 1, and internal and external cache disable.

Awesome and well planned system. Post some pics please!

I will get around to posting pics soon, but I thought I would share an update about the sound cards. I have a Sound Blaster Pro 1.0 and it works better with certain games than any Sound Blaster 16. Since I do not have space for another machine, I thought about putting both in this 486. Of course, I thought about the probable incompatibilities.

The SB Pro works fine in the 486 except for the gameport, which is apparently too slow for a 486. The SB 16's gameport is OK as far as I can tell, but at the moment I only have a Gravis Gamepad, not a true analog stick. Ideally I should use a speed adjustable gameport like a Gravis Eliminator.

Since I have an MT-32, CM-32L, SC-55 and SC-55ST either connected or connectable to the system, Adlib does not get that much use here. I know that OPL2 chips are unreliable at high speeds, but I have yet to encounter a problem that cacheoff will not solve in this respect.

But what about the conflict between the Adlib ports at 0388-038B? Both the dual OPL2 and the OPL3 are present at those locations. Conflict could only possibly occur during reads from the chips' status registers, not writes. However, I decided to use a different SB 16 in my machine, a CT-2940. This is an SB16 PnP card, which I used to be wary due to the configuration headaches and the hanging note midi bug. On the other hand, as I had a Roland MPU-401 in my system, that was irrelevant.

I was not using a PnP BIOS or OS, so I had to obtain Creative's Configuration Manager (CTCM) and Utility (CTCU). The first initializes the card, and the second allows you to change or disable the card's resource usage. The utility looks similar to and functions identically to Windows 9x Resource Manager.

With the utility you can enable or disable the gameport and the audio function separately. It is quite possible to use the card just as a gameport. The audio has multiple configurations, including those that eliminate access to the MPU-401 Midi, Adlib ports, the low and/or high DMAs and IRQs. I figure that any game with Sound Blaster 16 support should allow the use of alternative settings. The same cannot be said for early games with only SB support. They expect the card will be at A220, I7, D1.

So with a configuration that disables the Adlib ports, I should be all set unless I play a game by choosing an OPL3 option that programs the chip through the ports at 388-38B and not those at 2x0-2x3. In that case I would re-enable the ports. Even so, there may be a potential detection issue because the OPL2s and OPL3 chip are sharing the same addresses, but I think the likelihood is low that a real problem would occur.

Great Hierophant wrote:

1. The BIOS (AMI 8/8/93) does not support IDE drives larger than 504MB, so almost half the space of the CF card goes unused. I will get the XT-IDE Universal BIOS and stick it in the Boot ROM socket of the NIC. 504MB can get filled up really quickly, especially when you are using floppy versions of disk games.

4. I have had some issues with hard drive corruption, I am not sure whether it is due to my using the IDE Block Mode setting or using the fast speed modes on VLB IDE controller.

Have you considered using a 16-bit ISA SCSI card? An Adaptec 1520B or 1540CP come to mind as cards I've used succesfully in 386 and 486 machines. You can then get a 2 or 4 GB GB SCSI drive. If you are determined to use the Addonics external CF-to-IDE card adapter, you can use an ACARD AEC7720UC1 which allows you to hook an IDE hard drive, CD-ROM, or CF-to-IDE adpater up to the SCSI 50-pin narrow connector. If you want to use the Addonics CF card adapter, you probably won't have enough space to connect the ACARD adapter directly to the CD adapter, so you'll need to use an IDE extension cable. Any old IDE cable will do provided that you flip the pins such that each pin is straight though, or one-to-one.

Here's an image of the IDE-to-SCSI adapter,
http://www.acard.com/english/fb01-product.jsp … 1_idno=2&ino=43

Do not be fooled by the $249 list price. I know Microland Electronics (http://www.microlandusa.com/) sells them for $130, and they sometimes go for around $50-$99 on eBay.

I've atached an image of the ACARD IDE extension cable I made from an ordinately IDE cable. I learned of this trick from user Anonymous Coward. I had no idea the pins on an IDE cable weren't one-to-one until I ran into this issue. You'll need some longer than normal pin headers as well. I used ones I found on digikey, part number 609-3490-ND.

If you don't want to use a 3.5" external bay for the CF-to-IDE converter, you could always use some unmounted CF card adapter and hook it straight up to the ACARD, letting the two dangle inside the case.