First post, by WDStudios
Some of you may remember that, a while back, I posted a thread asking how much interest there was in making new hardware that replicated ye olde Win98-compatible hardware, so that people wouldn't have to dick around with emulators, virtual machines, third-party hacks, that sort of thing. It got derailed by
trolls polemicists who insisted on arguing about the technical details of a project that literally did not have any technical details to argue about, and was ultimately locked by a moderator who did not understand the difference between calling a response stupid and calling a person stupid. After that, I took a break from this forum, and I'm glad that I did, because I've learned some stuff about how such a project would or wouldn't work.
First, I was recently investigating the NES/SNES/Genesis clone market and learned about the Gamerz Tek Minigen and Analogue Mega SG. The Minigen is powered by either a TCT-6801 or a TCT-6803, depending on who you ask, and from what I've been able to gather, both chips are basically the entire Genesis crammed onto a single system-on-a-chip. I consider it very interesting that someone would create a new SOC that replicates a legacy system - and that such chips are apparently profitable enough to be made year after year. The Analogue Mega SG, on the other hand, is powered by FPGAs that have been programmed to replicate Genesis hardware. Upon learning this, I decided to contact a hardware guy that I know and ask about the possibility of replicating the AMD K7/K8 architecture on an off-the-shelf FPGA. His response was that such a chip would be able to achieve "a couple hundred MHZ. Maybe a little faster", and that interconnect delays, rather than voltage or heat output, was the limiting factor. An FPGA-based solution simply isn't an option for a project like this.
A few days or maybe a week later, as part of a research rabbit hole that started with looking for information on the Voodoo5, I went digging for information about the very last chipsets that were made for the K7 (nForce2 and KT880) and the first ones that were made for the K8 (nForce3 and K8T800). I think I was trying to find out if there was ever a GeForce FX 5-based IGP. I couldn't find one; as far as I can tell, nVidia went straight from the nForce 2 with its GeForce 4 MX IGP to the nForce 400 with its GeForce 6100 and 6150 IGPs. However, that doesn't mean I came up empty-handed. I ended up learning something that evaded me back in the day when I was building K7 systems: the K7 was choking on its 400 mhz front-side bus. The only K7 systems that benefited from dual-channel DDR-400 were the ones that had integrated graphics, where one memory channel was reserved for the CPU and the other for the northbridge/IGP. That was when I began to suspect a huge flaw in any kind of "Win98 mini" approach that involved putting a full-blown Radeon 9800 or Geforce 5950 in the CPU package: I hadn't considered graphics memory bandwidth, like, at all. After a little bit of searching, I was able to find some pretty shocking numbers. A 400 MHz front-side bus translates into 3.2 GB/sec of bandwidth. The graphics memory bandwidth on a discrete GeForce 5950? 30.4 GB/sec, almost ten times as much! Using a Pentium 4 with an 800 MHZ bus reduces that difference to five times as much, and the 1 GHz Hypertransport bus used by the last Win98-compatible K8 chipsets still offers only a fraction of the needed bandwidth. This lays bare a crucial design consideration: no matter the fabrication process, the clock speed, the cooling solution, or anything else, achieving the performance of a dedicated graphics card requires dedicated graphics memory.
Now I'm wondering what the best way would be to handle both the normal system memory and the graphics memory for a "Win98 mini". For example, there are normally 8-16 memory chips per DIMM, and although those chips could be put on the motherboard instead, the amount of real estate that they'd occupy is quite a bit bigger than the space occupied by a DIMM slot. However, that's all due to the memory demands and fabrication processes of any given time. Given that a half-gig is now the *minimum* size of a single memory chip, and given the low memory requirements of Win98 and compatible games, does it make sense to bother with DIMM slots at all? Or would it be better to just put two memory chips on the motherboard (one per channel) and call it a day? Can the GPU and dedicated graphics memory be put on the motherboard as well, or would an AGP slot and discrete card be necessary?
(yes, NOW it's appropriate to argue technical details)
Since people like posting system specs:
Core i7 Sandy Bridge @ 3.6 ghz
4 GB of RAM in quad-channel
Geforce GTX 780
1600 x 1200 monitor
Dual-booting WinXP Integral Edition and Win7 Pro 64-bit
XP compatibility is the hill that I will die on.