> Ok so you do know different. Why is there so little discussion of
> these on the list?
There are VERY VERY few people that have such systems. I only know of at
most a dozen in the US, and most of them do not participate in on-line
discussions. A few rairly use email.
> Is there a more appropriate list? Maybe as we all have different
> manufacturer's kit we have little to talk about, but we still face
> Similar problems, thing like tracking down media, repairing peripherals, fault
> finding logic, keeping the machine clean and stopping them rusting,
> keeping the offline support stuff working - keypunches, Flexowriters,
> Teletypes etc, though maybe that is not a problem for you as your
> machine has a comms controller.
The Computer History Museum is formalizing the restoration process, now that
several machines have either been restored, or are in the process.
Surviving systems from before 1975 are very rare animals, esp mainframes,
since so many of them have been scrapped for precious metals. Sadly, there
is even less software that has survived. CHM didn't start seriously
collecting documentation nor software prior to the move to the West Coast in
the 90's. While they have an impressive collection of hardware, and a pretty
decent collection of US computer documentation now, the software holdings
pre 1975 are minimal.
I will be giving a talk at VCF this Saturday on the CHM software collection.
I was at work and needed an EBCDIC code, came across this. A useful link if
you are using the old hardware and need a old code.
http://www.lookuptables.com/
Billy
sorry I couldn't resist ...
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
> I think the distinction I normally use is often called 'keeper'. That's a
> pun on 'Key Per Function' meaning a calcultor has, say, a key labelled
> 'SIN', whereas on a computer you spell it out. Byt that definition the
> HP41 is a calculator (although you _can_ spell out the function names if
> you want to), the HP9830 most vertainly isn't.
so what does this make the Sinclair ZX-80, ZX-81 and Spectrum systems?
(I am not even sure you *could* type in the commands, I think you *had*
to press the appropriate function key).
**vp
>
>Subject: A question regarding floppy drives functionality..
> From: Marian Capel <marian.capel at bluewin.ch>
> Date: Tue, 31 Oct 2006 18:26:22 +0100
> To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Since this list has a number of people that are very knowledgable on the
>subject :
>
>Am i correct in thinking that, given a custom FDC, i could run a modern
>1.44 floppy in FM mode, and at much lower data rates i.e. (say 50 KHz.) ?
You may not be able to run that slow but you could test by recording square
waves of varying frequencies and look at what comes back.
>Background : I am musing on how to give a small amount of storage, say
>around 100kb, to a very small low tech cpu.
>I do not care about speed and efficiency.
Myself for 100k I'd use a EEprom. Eprom or even 128k ram with a battery.
>I am aware that IDE-based solutions are simpler, both hard- and software
>wise, but I would prefer a floppy based solution.
FYI the slowest floppies are the oldest 5.25 like the SA400 and TM100
as they will reach down to 64khz, I did some testing once. I'd suspect
some of the later 360k drives would do well (slow data) too. I do
know that most of the 360k drives work fine at FM (single density) data
rates (125khz).
Allison
I just brought up my /34a and apparently it's sick. It has one DD11-PK.
Configuration is as follows:
1 - M8266 (A-F)
2 - M8265 (A-F)
3 - M9312 (A-B), M7859 (C-F)
4 - M7891 (A-F)
5 - Grant (D)
6 - Grant (D)
7 - Grant (D)
8 - Grant (D)
9 - M9302 (A-B), Grant (D)
What works:
Storing & retreiving various patterns from ram via the front panel works
fine in all cases.
Looping on CLR PC loops as expected
Looping on BR . loops as expected
Trap catcher works (first pass halts at 1030 filling ram, then a BR . loops
as expected).
The memory address test program fails though. It halts at 246 indicating a
memory addressing error. R1 points to 422. Examining memory via the front
panel shows the following:
420 420
422 177355
424 177353
426 177351
430 177347
So it looks to me like it is able to store 420 in 420, but nothing after
that. I would normally think there is a problem with the memory board
(M7891). However, I have replaced that board with 2 others, and all 3 boards
fail at the same address AND with the same values. I find that likely to
rule out the memory board as really being bad. In addition, I can deposit
and examine values to locations 420 through 430 via the front panel just
fine. It's my understanding that the KY11-LB puts data in memory via the
unibus, so I would think this makes it somewhat unlikely to be a backplane
issue. Is it a strong likelyhood that the problem is the cpu set itself
then, as that's what would be writing the values to memory during the
address test?
And as I type this, I just noticed something interesting. The numbers stored
in ram at 422 through 430 are the right numbers, just inverted logic. More
specifically if you invert all the bits in 177355 you get 422, if you invert
all the bits in 177353 you get 424, inverting 177351 gives 426 (all the
latter values being what I'd expect). I'm guessing there's a dead inverter
on the cpu set somewhere perhaps? But if that's the case, why does 420 get
set to 420 correctly??
Any advice is most appreciated :)
Jay West
Hi
Is there a way to clean printer heads from the outside, rather than
allowing so much ink to be wasted by the machine blowing the ink through
the heads to clean them.
(This must be in a FAQ. I just need to be pointed to where this has
been discussed a thousand times already.)
A bit of background:
I have an Epson CX6600 printer/scanner that has suddenly quit printing.
The company sent the machine to me to replace an earlier model that
developed the same problem.
Maybe this machine has the same problem, or maybe it just needs head a
more aggressive cleaning.
I've "blown the jets" a few times, using over half the ink in the
cartridges to do it, and the machine still barely leaves an image on the
paper.
(I keep a towel over my printers when I don't use them, and no one
smokes in the house.)
I'm hoping to avoid taking the time to crate and ship this machine as
well. I'm not really interested in another replacement anyway.
Thanks in advance for any help.
Greg P.
