anders@perdix.UUCP (04/07/87)
I have a few questions about the new Apple Mac II.
* Are someone working on porting UNIX to it? In that case which UNIX?
How and when will it be available? Is Apple doing something themselves?
* Does Mac II have support for demand-paged virtuall memory or can it
be upgraded easy?
* Price ?
* Anyone have practical experience with it?
Thanks for any relevant information.
Anders
Anders Ardo Tel: int+46 46 107522
Dept. of Computer Engineering Telex: 33533 LUNIVER S
University of Lund
P.O. Box 118 UUCP: anders@perdix.lu.se
S-221 00 Lund, Sweden BITNET: ddtnet@seldc51m5d@bobkat.UUCP (04/13/87)
In article <3423@osu-eddie.UUCP> bob@osu-eddie.UUCP (Bob Sutterfield) writes: >In article <173@perdix.lu.se> anders@perdix.lu.se (Anders Ardo ) writes: >> >> I have a few questions about the new Apple Mac II. >> [ ... ] >>* Anyone have practical experience with it? > >It runs quite nicely, but thrashes inconveniently when memory-starved >with large applications. But then you expect that from anything. > >-- > Bob Sutterfield, Department of Computer and Information Science Correct me if I'm wrong, but the belief in this neck of the woods is that the Mac II has no DMA controller. Because of this, the processor is responsible for managing transfers from the SCSI (or whatever) interface, so I/O bound processes could consume alarming amounts of processor resources. Has anyone used a system with such hardware (or similarly, a very greedy DMAC)? Is the suspicion correct? -- Mike McNally, mercifully employed at Digital Lynx --- Where Plano Road the Mighty Flood of Forest Lane doth meet, And Garland fair, whose perfumed air flows soft about my feet... uucp: {texsun,killer,infotel}!pollux!bobkat!m5d (214) 238-7474
jon@eps2.UUCP (04/15/87)
In article <3423@osu-eddie.UUCP>, bob@osu-eddie.UUCP (Bob Sutterfield) writes: > Apple has already done it. The word is that it will be on the street My understanding was that Unisoft did it. > speak). They include signals, networking, and "selected utilities". Yup. I was told that they added all the BSD IPC stuff, with the sockets interface. I'm impressed. Good job, Unisoft. > It still has the SV file system - not the Berkeley fast one, nor with > long names. Expect SVr3 streams, but (for now) no RFS nor mpx > streams. Yeah, 1K blocks. Some customers have already expressed an interest in putting the McKusick file system in A/UX. > To run A/UX (or Oreo or whatever it's called today) you must install > the optional PMMU chip - their own Programmable Memory Management > Unit. I believe that is a Motorola 68851, the *Paged* Memory Management Unit. Regarding SCSIs without DMA, it would definitely suck if you had multiple users and/or multiple processes running. But, on a single-user system with just one process running, it might be acceptable, because the only program that could run is sleeping waiting for I/O to complete anyway; so you could tie up the CPU polling for data from the SCSI host adapter. Plessey had a 1K FIFO on one of their CPU boards that has an NCR5386 SCSI host adapter. It generated interrupts when it was half full, then the CPU would come along and read 512 bytes out. I've never used it, but it's possible that the disk controller could transfer continuously into the FIFO for many consecutive disk sectors, because the CPU would start to empty it quickly when it got half full. The penalty you pay is moving bytes around with the CPU, but with interrupts from the FIFO you don't waste time polling for data. Jonathan Hue DuPont Design Technologies/Via Visuals leadsv!eps2!jon