First post, by Yushatak
- Rank
- Member
My favorite retro box of all time (so far, anyway) is my Compaq Presario 425. It's a 486 box that's got an all-in-one design, meaning the video card is integrated and has a proprietary connector. I crammed a Pentium Overdrive into this Socket 1 beast (yes that works, heheheh) and maxed it's RAM out at 24MB (4MB onboard, 2x8MB sticks - can't take larger). The chipset is a mix of VLSI (brand) chips. I've got DOS 7.10 on it with a DDO to let it run from a larger-than-normal drive so that I can cram it full of games and stuff. Everything's great, but if I stick a copy of Win95 on it it lacks the RAM to play a DOS game from within Windows, and that upsets me a tad. As well, while it can run Quake and Duke3D like a beast for a 486 (thanks to the POD's floating point unit) it isn't quite as fast as I'd like. While I know that the video card is an issue here, I think that the RAM is also a bit small for Duke3D.
I'd love to upgrade the RAM and the video card on this, but I'm not a hardware genius, more of a software genius. 😜 There's also the question of cache.
My only idea for modding the video card would be to use the pinout for the proprietary monitor connection to wire up a VGA->(whatever this is) adapter and hook up a faster card in one of it's two ISA slots (it has no PCI - shame), but that would be a bit ghetto and take up one of my two ISA slots. A more advanced hardware modder might be able to assess the possibility of a drop-in replacement for the GPU chip itself (a Cirrus Logic GD5420) or a simple-to-adapt replacement, and then replace it via SMC desolder/resolder - out of my skill range, unfortunately, but perhaps you could help me assess the possibility? Also, the GPU is capable of addressing more VRAM - more upgrade options perhaps in that department? It's at 512K stock, chip supports 1MB iirc.
As for the RAM, I've got three thoughts. The machine has 4MB onboard, and two slots. You can put up to 8MB in each slot, and each slot is it's own bank. This means that perhaps the onboard bank could have another 4MB soldered on - piggybacked perhaps - and bring the box up to 28MB. Not a big upgrade, but a thought. The second idea is a RAM riser. A device that would plug into one or both of the SIMM sockets and provide more sockets. This would help with physically getting more RAM in, but it would probably be recognized as just a big stick of RAM, so that probably wouldn't help any more than finding 16MB+ FPM SIMMs to put in the existing slots. The third idea is related to the chipset - I've read some documentation on the chips and they are very late, very cheap/tightly integrated chipsets - not bad though. The chipset supports up to a large amount of RAM, but more realistically up to 256MB at least, with that 256MB being cacheable even if the machine has a 1MB L2 cache. Perhaps with some clever tweaking of the pins/traces or a BIOS mod this capacity could be utilized in the form of upward of 2x128MB RAM sticks (they exist..)?
Speaking of the cache, I'm honestly not sure if the box has any. If not, then it could sure as hell use some. The chipset supports lots of cache, some crazy amount like 2-4MB (the chipset also supports some crazy amount of RAM like 1-2GB, but probably never tested or implemented that way) - anyway I'd be happy with even a little bit of L2 cache, but 1MB would be brilliant, especially if I could get the RAM up to 256MB (not that I need it that high, but I'm all for crazy maxed-out stuff).
Not that I'm unsatisfied in the CPU department, but I would be open to suggestions for speeding that up as well - 83Mhz POD is great, but in integer performance it's beat quite handily by the 5x86-133 - not that anything I'm doing on there currently uses all of that power - again though, in the name of maxing out the box.
Thanks!
Oh and I have the spec sheets for the relevant chipset chips (not easy to track down, at least for me) - if you are interested in assessing this box's modding potential and think they'd be helpful, let me know - any other info ya might need too.