zmacv14@tsun3.doc.ic.ac.uk.doc.ic.ac.uk (C P Brown) (11/18/89)
I have a 1Mb A500 and a custom-designed box which has three slots for A2000
cards, one of which is taken up by a Xetec 85Mb hard disk, and another I have
appointed for an A2286 which I plan to buy soon. Memory expansion and a
processor upgrade are definitely in my near future, and I have one slot spare
to acheive this. However, having investigated the processor upgrade market, I
am left in a bit of a quandary. The following options are available to me:
1. 68010 approx 30 pounds
I can't see that this will improve things much except maybe some maths
ops, then again I don't know the specific differences between the 68000
and the 68010.
2. 68000 at 16MHz approx 180 pounds ("Processor Accelerator")
Seeing as the chip must fetch instructions at 8MHz (I assume), surely the
chip will be spending much of its time waiting, resulting in maybe a 10%
increase in speed. Again, feel free to correct me on this.
3. 68000 at 16MHz with 8K 80ns RAM cache approx 150 pounds
A techie chap at a distributor told me that this is a brand new innovation
and the fast-ram caching results in a 65%-100% increase. Has anybody used/
heard of this yet?
4. CSA's Turbo 68020 at 16MHz approx 300 pounds
Similar to point 2 above, although it's a more powerful chip, it must spend
time waiting for instructions. Maybe 60% increase?
5. A2620 approx 1100 pounds
Now this I like the sound of; 2Mb of 32-bit RAM, 68881 built-in and of
course it is Commodore-sourced. Also the MMU to relocate KS would be useful,
and the software processor selection I like. I have been told that this card
needs a 'CPU' slot - is this the same as an ordinary Zorro-II or something
different?
What I'd like to know is the experiences that other users have had with any of
the above, ie typical speed increases for normal programs and those which have
had 68020/68881 versions written, software incompatibilities etc. If I buy a
68000-type accelerator, I still have the slot free which I can use for 2Mb of
RAM, about 300 pounds. Also I have been told that 1.3 maths libraries detect
a 68881, so if I buy a 68000/68881 combination then I will get support with all
programs that use the 1.3 libraries. Is this true? And how many programs fall
into this category? Also, if I buy a 68000/68881 and 2Mb of RAM this comes to
600 pounds, about half the price of an A2620 but non-standard and definitely a
less powerful combination. Please advise. I use SA4D, Turbo Silver extensively
but also do many compilations (C, M2, Prolog).
Another alternative I suppose is to wait until Commodore release the Amiga
which was announced here recently; a 68030 card, 1Mb chip/1Mb fast RAM and
asynchronous clock to acheive a magical increase in performance. The quoted
price? 1500 pounds. Sounds too good to be true, as I could then drop in my
hard disk etc and flog the A500.
Any comments, suggestions, performance info, corrections gratefully received.
Thanks in advance, I'm so glad I stuck my neck out and bought an Amiga all that
time ago - the Amiga fraternity is so helpful!
Phil