cdh%bbn-unix@sri-unix.UUCP (02/07/84)
From: Carl D. Howe <cdh@bbn-unix>
I saw the Mac at a demonstration presented here at BBN
Communications. However, I think you will find more useful
information about it in the February issue of Byte magazine than
than you will anywhere else, including from the salespeople. The
articles shows pictures of boards, has interviews with the
designers, descriptions of the contents of the 64KBytes of ROM,
memory maps, etc. It really is a good pair of articles; read them
if you want to really know what's inside.
My reaction: it's a neat thing. However, in keeping
with Apple tradition, it's overpriced. Remember that this thing
has only 50 chips in it. They keep emphasizing that there are
fewer chips in it than in an IBM PC monochrome board. Note
however, that it costs almost an order of magnitude more. The
monitor is nothing special; it's not even high resolution (i.e.
it is < 15 MHz). The disk is only $200 or so, ditto for the mouse.
I believe that even at the $1000 price
they are offering universities, Apple will make money within the
next year. Which means that $2500 is an awful lot to spend for
that hardware.
On the other hand, the software is nice and worth the
price. As a matter of fact, I believe the Mac software is
underpriced compared to the overpriced hardware.
Beware of sales hype, however. Currently, the Apple
sales people seem to be boasting about the 1 MBit "virtual slot"
bus. Be careful. That's externally clocked speed; maximum
internally clocked speed is 230 KB. If they are going to do
things externally clocked, they had better decide how long they
are going to allow their bus to be and who is going to source the
master clock. If they really intend to run at a Megabit with
twisted pair, a) they had better be careful about termination,
and b) they had better not run it over about 200 ft. Those
concerns are dictated by RS-422. Of course, that's fine if this
is a peripheral bus. It's not so great if this is considered to
be a local net.
In fact, there is a more severe caveat associated with
their serial bus. According to the interview with the designers,
they are using the Woz disk controller which requires the CPU to
transfer all bytes to and from the disk without DMA. In the same
article, they talk about how clever they are to poll the serial
port when they are doing disk transfers so that they don't lose
bytes on the serial line. They poll the serial port every 4
nibbles. A bit happens every 4 microseconds (every 2
microseconds in high density mode). That means they poll the
serial port every 32 or 64 microseconds, depending upon which
number you believe. That puts an upper speed limit on the bus of
either 250 KBits or 125 KBits. That's not a megabit, folks.
I realize I'm carping a lot about the serial bus.
Remember however: this is your only handle on the machine for
peripherals. If it isn't so good, you're going to notice it
forever.
Question: where does the hard disk go? On the serial
bus? On the port for a second floppy? Can the processor handle
a hard disk's data rate? If it goes on the serial bus, can it?
All interesting and unanswered questions.
The lack of multitasking is a bit disconcerting. The
designers said that they got a lot out of using a simpler memory
mapper than that in the Lisa. That's scary; it might mean that
there isn't enough support there to really run multiple parallel
processes. However, it's just not possible to tell yet from the
documentation I've seen.
Again, all in all, this is a nice machine. They got an
awful lot of things right. They will probably make it better.
It will keep the micro world from turning into IBM and the 7
clones. This is a wonderful $1000 machine; the question is
whether it is just as wonderful at 2.5 times that price.
Carlfarber@udel-ee.arpa (02/07/84)
From: Dave Farber <farber@udel-ee.arpa> Just for the record, ONLY 20 Universities get the Mc for $1050. The rest of us poor slobs have to pay real money. Personally I think that was a stupid way of doing it. With academic attitudes how would you like to be told you are one of the lesser souls who pay for them. Bet they dont sell many to the rest of the University world. I think that was very poor thinking.
tbm@hocda.UUCP (T.MERRICK) (02/13/84)
Or Marketing Know-How Apple has managed to put the Mac on the cover of Byte, Popular Computing, Softalk, and Popular Science not to mention MacWorld. Is that a record? That is a lot of Review material (and available to most people). Are there others? Tom Merrick ATT Bell Labs MV