While the nitty gritty detail of recollections captured when still fresh in memory can be fascinating, I especially appreciate reflections written a few decades later as it allows putting the outcomes of key decisions in perspective, as well as generally enabling more frank assessments thanks to fewer business and personal concerns.
Pretty sure the author meant write 640 kilobytes.
At a time when PC memory maxed out at 640 megabytes, the fact that the PCI bus could address 4 gigabytes meant that quite a few of its address bits were surplus. So we decided to increase the amount of data shipped in each bus cycle by using some of them as data. IIRC NV1 used 23 address bits, occupying 1/512th of the total space. 7 of the 23 selected one of the 128 virtual FIFOs, allowing 128 different processes to share access to the hardware. We figured 128 processes was plenty.
PC memory was nearly always sold in powers of two. So you could have SIMMs in capacity of 1MiB, 2MiB, 4, 8, 16MiB. You could usually mix-and-match these memory modules, and some PCs had 2 slots, some had 4, some had a different number of slots.
So if you think about 4 slots that can hold some sort of maximum, we're thinking 64MiB is a very common maximum for a consumer PC, and that may be 2x32 or 4x16MiB. Lots of people ran up against that limit for sure.
640MiB is an absurd number if you think mathematically. How do you divide that up? If 4 SIMMs are installed, then their capacity is 160MiB each? No such hardware ever existed. IIRC, individual SIMMs were commonly maxed at 64MiB, and it was not physically possible to make a "monster memory module" larger than that.
Furthermore, while 64MiB requires 26 bits to address, 640MiB requires 30 address bits on the bus. If a hypothetical PC had 640MiB in use by the OS, then only 2 pins would be unused on the address bus! That is clearly at odds with their narrative that they were able to "borrow" several more!
This is clearly a typo and I would infer that the author meant to write "64 megabytes" and tacked on an extra zero, out of habit or hyperbole.
I can’t find the purchase receipts or specific board brand but it had four SDRAM slots, and I had it populated with 2x64 and 2x256.
Now we have Vulkan. Vulkan standardizes some things, but has a huge number of options because hardware design decisions are exposed at the Vulkan interface. You can transfer data from CPU to GPU via DMA or via shared memory. Memory can be mapped for bidirectional transfer, or for one-way transfer in either direction. Such transfers are slower than normal memory accesses. You can ask the GPU to read textures from CPU memory because GPU memory is full, which also carries a performance penalty. Or you can be on an "integrated graphics" machine where CPU and GPU share the same memory. Most hardware offers some, but not all, of those options.
This is why a lot of stuff still uses OpenGL, which hides all that.
(I spent a few years writing AutoCAD drivers for devices now best forgotten, and later trying to get 3D graphics to work on PCs in the 1990s. I got to see a lot of graphics boards best forgotten.)
> “This was the most brilliant thing on the planet. It was our secret sauce. If we missed a feature or a feature was broken, we could put it in the resource manager and it would work.”
Absolutely brilliant. Understand the strengths and weaknesses of your tech (slow/updateable software vs fast/frozen hardware) then design the product so a missed deadline won’t sink the company. A perfect combo of technically savvy management and clever engineering.
pjmlp•4h ago
Back then I was quite p***d not being able to keep the Voodoo, how little did I know how it was going to turn out.
stewarts•1h ago