mmm@cup.portal.com (Mark Robert Thorson) (07/20/90)
Does the Micro Channel on the Model 80 have 32-bit address and data? Does the DMA controller on a Model 80 system board support 32-bit data transfers? Does the DMA controller support 32-bit addressing, or just 24-bit? Do I have to get an account on Prodigy to get my PS/2 questions answered :-) Thanks for any info you can provide!
nathan@yatton.inmos.co.uk (Nathan Sidwell) (07/23/90)
In article <31898@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >Does the Micro Channel on the Model 80 have 32-bit address and data? Yes, though only on 3 MCA adaptor cards. These 32 bit slots also have a 'matched memory' protocol which allows the 386 to access _memory_ faster They do not have to decode all 32 address lines, as there is a 24-address valid flag, which can be used. >Does the DMA controller on a Model 80 system board support 32-bit >data transfers? No, It only supports 8 and 16 bit transfers >Does the DMA controller support 32-bit addressing, or just 24-bit? Only 24 bit addressing. Another thing about DMA on MCA, is that it is executed by a read and then a write cycle, thus being half as fast as the actual bus bandwidth. To get the fastest data transfer to/from a card, that card must be a bus master. --------------- So what's your mission statement? ---------------- Nathan Sidwell, INMOS Ltd, JANET: nathan@uk.co.inmos Aztec West, Bristol, UK UUCP: ukc!inmos!nathan My indicision is final (I think) INTERNET: nathan@inmos.com