Large PC System Layout author Neil Franklin, last modification 2004.09.28 For 32bit and 64bit large PC systems Typical CPUs 80[3+]86, 680[2+]0, RISC Multiprocessor and DMA IO capable backplane/bus 32bit A/D multiplexed, provides slot IDs 32bit bus 4+28bit 16cards*256M can be split into 2 8-card buses in 2 chassis with own power, mirroring 64bit nodes 8+4+4+(8)+40bit 256chassis*16cards*16nodes*1024G each processor or controller with its own RAM is a node 4 1:1 lines to card controller, from that 4 1:1 hypercube to other 15 cards an on each controller 1 1:1 to external, for other chassis either 2 chassis with 16 1:1 (= 5dim hypercube), or switch with n chassis bus only for DMA transfers for off-card stuff interrups via DMA to target processors IRQ control register in IO space cards at top section 16*64k for IO devices, rest RAM integrated address decoder driven by slot ID, and RAM/IO decode also point for connecting BIOS or driver ROMs, 8bit or even serial left over pins can be used as PIO/VIA style devices IO bus from 1 adapter card , using 256M as (15devices+card)*16M uses only 8|16bit a/d transfers, so 4|2 times slowar as main bus no problem as IO slower than RAM, and possibly 2 IO buses for mirroring later possibly SSA/serialSCSI/SATA/Firewire/USB-like sys for simpler cabling simple version only devices 1|2|4|8 with "stepped" ribbon cable or use IEEE488-like parallel poll drives have own cache up to 16M directly visible in address space controllers must have own RAM based microcontroller to process IO 4kx8 or 4kx16 for code, 256 of these for data/IO, all in CPU adress space these then issue DMA accesses and Interrupts to target processor video/sound/key/mouse/etc card 8M for video, 4M for sound, 2M for UserIO bus video controller microcontroller for retrace, etc also possibly for hardware based windowning, collecting video data sound large microcontroller or DSP UserIO bus controller 16 track microcontroller 1kx(8|16) for self+15devices serial bus, slow but not much data, an usually access by microcontroller in monitor 1:8 decoder first 8 devices, second external 1:8 for 7 more in devices serial attached PIO/VIA like chip, used by microcontroller