Re: Apple IIc+ & Memory

[hlevinsn@andromeda.rutgers.edu (Hank Levinson)]

buggie@ben06.unm.edu (stephen e buggie) writes:

>The IIC PLUS can accept the RAM EXPRESS one meg ram card.  I have it, but
>its not for sale.    Nice graphical screen on the RAM EXPRESS self-test
>disk.

>Speed of the IIC PLUS is 4 MHz unless it is slowed down at power-on.

>Normally, you run it at 4 MHz except for games.

>Steve Buggie			buggie@unm.edu

	Since I posted that the speed of a IIc+ is about 3.6 Mhz, and Prof.
Buggie stated it ran at 4 Mhz, I decided to try to find out exactly how a
IIc+ compares to a IIc. I had both run a simple counting program
simultaneously. I supposed that the IIc+ would get to 36,000 or 40,000 in
the time it took the IIc to count to 10,000. The results were surprising.

	The first program I had them run was as follows:

		10 HOME: N = 1
		20 N = N + 1: HTAB 10: VTAB 10: PRINT N
		30 GOTO 20

	The program was entered into both machines, "RUN" was typed and both
<RETURN> keys were pressed as simultaneously as my two hands could manage. To
my amazement, both macines executed the same counts AT THE SAME SPEED! I
stopped both, again as simultaneously as possible with my two hands, and they
read almost the same numbers after counting to 100,000.

	I thought the reason lay in their printing each number they counted.
Performing I/O inherently slows a machine down. So I changed the program to:

		10 HOME: N = 1
		20 N = N + 1: IF N = 100000000 THEN M = M + 1: N = 1: GOTO 20
		30 GOTO 20

	Now there would be no I/O. <CONTROL> <RESET> would have to be pressed
to stop the programs (simultaneously). The IF... THEN part was added since I
thought the programmight count beyond 100,000,000 in which case N would
switch to scientific notation and would not increment by 1 any more. That
turned out to be unecessary; after 3 hours the IIc was at 337,984 and the IIc+
was at 1,150,438. Now 1150438/337984 = 3.4038. If the IIc ran at 1 Mhz, the
IIc+ was running at 3.4038 Mhz. To see if the ratio would be affected much by
doing a longer run, I ran both programs for 8 hours. The IIc reached 2,338,512
and the IIc+ 7,463,927. 7463927/2338512 = 3.4049, a difference of .0002 in 5
more hours.

	In case the conditional IF... THEN slowed things down, I ran a much
simpler program:

		10 HOME: N = 1
		20 N = N + 1: GOTO 20

	   after 10 hours, the IIc had counted to 10,683,218 and the IIc+ to
35,958,758. 35958758/10683218 = 3.36591, slower (!!!) than the longer program.

	I conclude that calls to the BASIC interpreter, which translates each
line to machine language, executes it and then goes to the next line (the same
line in this case; GOTO 20), may have also slowed down the IIc+ from its native
speed. On the other hand, these calls should have been executed at the IIc+'s
faster speed and it shouldn't have made any difference in relative speeds of
the two machines.

	However, it seems to me that the IIc+ goes at a speed of closer to 3.6
Mhz than to 4 Mhz. There is indeed a 16 Mhz crystal in the IIc+, but does it
clock the machine or does it synchronize output to the monitor as the early
PC's do? I remember seeing somewhere that the IIc+ ran at 3.6 Mhz, but I fail
to remember exactly where I saw this.

	If anyone can devise a test to show the IIc+ runs 3.6 (or 4) times
faster than a IIc, please let me know. All this raises the question of "How
fast does a machine go?" Do we simply measure the speed at which its CPU chip
is clocked, or shall we see how fast it executes a program? (I once had a car
whose speedometer was capable of reading 160 mph.; luckily I never attempted
it!)

H. Levinson   hlevinsn@andromeda.rutgers.edu

P.S. This posting was delayed several days by problems with Rutgers' andromeda
     system's access to this newsgroup.



>Gus Vilomar (gvilomar@bellsouth.net) wrote:
>: Does anybody know how I can find out the Mhz and memory of my Apple IIc+?
>: Once I know this, how can I add more memory?  How much?  and where can I get
>: it?

>: Gus