20 Aug
2004
20 Aug
'04
8:54 a.m.
Here?s a question for you guys. One of my HP2000 friends asked me
what the difference was between a 2100a and a 2100s. Now, I have
done a fair amount of maintenance on both and I can?t recall that
I ever paid any attention to any difference between the two.
Does anyone know of any differences between the two other than the
name on the front plate?
Thanks,
Mike Gemeny
20 Aug
20 Aug
9:04 a.m.
Mike wrote...
what the difference was between a 2100a and a 2100s.
Now, I have
There really isn't any difference, sort of.
The 2100S came with a set of options that the 2100A didn't come with by
default but which could be ordered with the 2100A. I forget which options,
perhaps hardware FP.
In addition, the 2100S had sockets on A1 & A2 for addon microcode, which
many 2100A's didn't have. If you wanted to add microcode to the A you got a
new rev of A1 or A2 card that had sockets (effectively turning it into an
S - sort of).
Jay
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9:22 a.m.
Jay West wrote:
Mike wrote...
Surely the 2100S has user-writeable microcode? The front panel
says "Microprogrammable Systems Computer":
http://www.gifford.co.uk/~coredump/hp2100s.htm
--
John Honniball
coredump(a)gifford.co.uk
what the difference was between a 2100a and a
2100s. Now, I have
There really isn't any difference, sort of.
The 2100S came with a set of options that the 2100A didn't come with by
default but which could be ordered with the 2100A. I forget which options,
perhaps hardware FP.
2:13 p.m.
Surely the 2100S has user-writeable microcode? The
front panel
says "Microprogrammable Systems Computer":
See the rest of my 2nd paragraph previous :)
The 2100S, from the factory, had sockets where you could plug in user burned
microcode chips. The 2100A did not. However, if you ordered addon firmware
for the 2100A, you could get the socketed version of the cards.
If you mean user writeable microcode as in not having to burn your own
chips, either the 2100A or 2100S could have that option board installed.
Separately ordered and purchased option board, not to be confused with the
open rom sockets on A1/A2.
Jay
23 Aug
23 Aug
1:10 a.m.
John wrote...
Surely the 2100S has user-writeable microcode? The
front panel
says "Microprogrammable Systems Computer":
As a followup - I just found over the weekend something I wasn't aware of.
Apparently the 2100A/S isn't "entirely" microprogrammable. In order to
maintain full compatability with the earlier systems (2114/2115/2116), about
2/3 of the instruction set is microprogrammed (the base set of microcode in
module 0). The other 1/3 of the base instruction set is actually done in
hardware - mostly. This is because the few instructions that are built into
the hardware would take too long to execute in microcode. However, for those
hardware based instructions to execute, that circuitry needs to be enabled
via microcode instructions. Fascinating, I had no idea.
Regards,
Jay West
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24 Aug
24 Aug
4:49 a.m.
On 23 Aug 2004 at 8:10, Jay West wrote:
As a followup - I just found over the weekend
something I wasn't aware
of. Apparently the 2100A/S isn't "entirely" microprogrammable. [...]
The other 1/3 of the base instruction set is actually done in hardware
- mostly.
The 21MX M/E/F computers retain some of this as well. The alter-skip and
shift-rotate instruction groups are implemented pretty much in hardware.
The microcode for these instructions basically just executes ASG and SRG1/2
micro-order "specials," which set up the hardware to implement the
instructions directly.
I don't know if this carried over into the A-Series or not. The A700 ERD
suggests not, but HP didn't provide microcode listings in this publication
to confirm.
-- Dave
7425
days inactive
7429
days old
5 comments
4 participants
participants (4)
-
coredump＠gifford.co.uk -
jdbryan＠acm.org -
jwest＠classiccmp.org -
MGemeny＠pgcps.org