Having secured a copy of Tom Pittman's Tiny BASIC on paper tape
(autographed by the man himself!), I'm in the process of adding a
teletype simulator to the COSMAC Elf simulator. It's a bit strange
because the 1802 code does bit-banged serial i/o, and my simulated
teletype has to do bit-banged serial i/o back at it. At least
initially, rather than hack all the 1802 code to run at a faster baud
rate, I'm simulating 110 baud with my "teletype", so most of the time
the emulated 1802 and the emulated teletype sit there waiting for each
other to send data. It's _almost_ working, but I'm getting some odd
results that I think may stem from an incomplete understanding of the
way the ASR-33 and others of that vintage send and receive data. I'm
testing with some code in an article about interfacing the Elf to a
Teletype, so I'm pretty sure the Elf code is correct. I'm using 110
bits per second, no parity, 8 data bits, one low (logic 0) start bit,
and one high (logic 1) stop bit. It seems to like the data
low-order-bit first, but I have nothing that confirms that how it should
work. I'm also working from the assumption that the data bits, the stop
bit, and the start bit are all the same length. Also, I'm assuming that
the "110 bits per second" includes the time for the stop and start bits,
but I'm not sure of that either. It seems to be transferring
characters; I get consistent hex values for each character I send to the
Elf, but they seem to usually be either shifted left or right by one
bit, or they have the high bit set when it shouldn't be. It feels like
I've either added extra bits or am missing some in there somewhere. Can
someone who knows this information for sure clear these things up for
me?
-Bill Richman (bill_r(a)inetnebr.com)
http://incolor.inetnebr.com/bill_r - Home of the COSMAC Elf Microcomputer
Simulator, Fun with Molten Metal, Orphaned Robots, and Technological Oddities.
>I didn't see any of the Apple II stuff that Tom saw
Probably because I bought them all. :-)
>I did see 3 TRS-80s, all model 1, level 2, one with expansion box and 2
>floppy drives
I missed those (probably would have purchased them, as I don't have much
TRS-80 stuff). The only TRS-80's I saw were a $50 Model 100 and a $25
CoCo II.
>Nothing else of interest... no TTYs, nothing S-100 (I rummaged through a
number
>of boxes of PC cards and assorted junk, just to be sure), absolutely
>nothing Ohio Scientific.
I saw a TI Silent 700, one of the portable models. I've _never_ found
any S-100 or Ohio Scientific at any Hamfest around here.
Tom Owad
I have never really understood the purpose of the M1 pin or cycle. Can
anyone in simple terms explain it's purpose?
----------------------------------------
Tired of Micro$oft???
Move up to a REAL OS...
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####/ / / / / / / / / / / / | /###
###/ /__ / / / / / / / /_/ / / |####
##/____/ /_/ /_/ /_/ /_____/ /_/|_|####
# ######
("LINUX" for those of you
without fixed-width fonts)
----------------------------------------
Be a Slacker! http://www.slackware.com
Slackware Mailing List:
http://www.digitalslackers.net/linux/list.html
Well I powered the PDP-8f tonight and guess what? The PS is toast.
I'm not much surprized either. Anyhow this one has a hard short of the
kind when power is turned off the room light dim. Next step is to pull
it out of the case and inspect and meter it for where the short is.
Anyone with a schematic? This one is the rear mounted style with the
cover that says, do not operate with cover removed for more than 15
minutes. Don't need the whole prints but only some things verified.
Is this a low voltage switcher? Or linear?
Is there more that one secondary on the transformer?
Both large fans are gone too. the small PS fan is not tested yet. but
it's stiff so that ones gone too. fans I have plenty of.
Did I mention it was a clean one? ;)
Allison
I was at my grad school yesterday, and visited the guy I did vaxcluster admin
work for back in 1992-93. A sad experience, I'm afraid. Turns out my guess
was wrong, the LN-O3s appear to be long gone, first of all. Second, they've
migrated away from DEC equipment in general to a mix of NT and IBM AIX machines.
The cluster I used to run, from the sound of things, has been reduced to only
the server, the vax 4000/500, and it's off maintenance contract and scheduled
to be pulled from service within a year. *sigh* Sic transit gloria Vaxen.
A silver lining - if I keep after the guy, I'm thinking he might take me up
on my offer to haul it all away for free. What I'd do with an 8350, 5
microvaxen and so on in addition to the 4000/500 (assuming they still have all
the members of the cluster) I dunno, but if it comes up, I'll figure it out. :)
--
Jim Strickland
jim(a)DIESPAMMERSCUMcalico.litterbox.com
-----------------------------------------------------------------------
Vote Meadocrat! Bill and Opus in 2000 - Who ELSE is there?
-----------------------------------------------------------------------
Hi,
----------
> From: Don Maslin <donm(a)cts.com>
> To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
> Subject: Re: Collectors list
> Date: Wednesday, March 31, 1999 1:09 PM
>
> On Wed, 31 Mar 1999, emanuel stiebler wrote:
>
> > Hi all,
> >
> > Because i feel so lonely here in Denver, i got the idea of collecting a
> > list of the listmembers. I simply want to see, in what areas you can
meet
> > people an what they collecting.
> I think that zip codes are only useful for mailing.
I thought about the zip code because you could sort the list very easy.
And in the sorted list, you could easy find out, if anybody is near you.
But ok, we can do a list with:
country/state/city name interests
so it still can be sorted.
thanks all for your attention ;-))
cheers,
emanuel
BTW, i don't like to see real email-addresses here, i get enough spam
already :-((
>> Anyone with a schematic? This one is the rear mounted style with the
>> cover that says, do not operate with cover removed for more than 15
>> minutes. Don't need the whole prints but only some things verified.
>At the risk of sounding like a complete and utter moron, why can't you
>operate for more than 15 minutes with the cover removed?
Because without the cover the airflow from the fans won't properly
go over the components needing to be cooled.
Remember, unlike PC-clone cases, where the fan on the back provides
minimal cooling to the contents of the box, most non-PC-clones actually
have fans to ventilate the guts.
Tim.
I need to reformat a bunch of old 8" floppy disks for use on a Terak
system with single sided single density shugart drives. Terak's
cannot format floppies (well, actually I recall a program that
could format, but it required special hardware and DSDD drives on
the Terak, which I dont have).
I will attempt to format the floppies on a Cromemco Z-2 system
with DSDD drives. Assuming this even works, I'm wondering if I
should buy a tape eraser and use it on the floppies before
attempting to reformat them. I need the 'standard' SSSD format,
which I think is 26 sectors, 128 bytes/sector.
Any suggestions on the best way to proceed will be appreciated. I
need to backup the old floppy disk software I have before time or
accidents cause me to lose some of it forever.
-Lawrence LeMay
lemay(a)cs.umn.edu
PS: I'm looking into obtaining permission to distribute the software
and manuals and operating system that were developed here at the
University of Minnesota, Minneapolis.
> Bzzzt!
>
> In asychronous communication, the rated speed of the channel in bits per
> second *includes* the start, stop, and parity bits.
>
> The ASR-33 did transmit (and receive) 110 bits per second, even though
> only 70 (not 80) were usable data.
I think the figure is 80, not 70, for the usable data. (I won't get into the
baud/bps argument). Ten whole characters. The ASR-33 doesn't do anything to
the msb, except have an option to generate parity there in the _keyboard_. You
can send ten 8-bit characters per second, 80 bits of data, to a TTY and all 80
bits will appear on the punch. You can read ten characters per second from the
punch and all 80 bits will be sent down the line. It's only typing on the
keyboard in which usefulness is restricted to 70 bits.
Philip.
Hey gang, still sorting out stuff I really cannot keep over here at the new
house.
This is an item I must part with:
Complete ZDS 1/40 Development System with Z80A emulator pod. Dual 8" floppy
drives. About 1977-'78 vintage. Runs RIO (the OS), BASIC and of course, a
Z80 assembler/linker. Have software floppies and docs. Zenith Z-19 terminal
is part of this system. I haven't used it for at least 12 years or so.
System is in two sizeable desktop cases each 19" wide x approx. 17" deep x
10" high. The main unit weighs about 30 lbs (I'm guessing as I don't have
the scales over at the old house where the syst. is still at), the dual 8"
floppy drive unit is maybe 45 lbs and a separate batch of s/w and docs
should be around 20 lbs or so. The Z-19 should be around 25 lbs I think.
Packed away somewhere in a box in the new library upstairs is the s/w and
docs. Gotta dig them out when I get a bit of time tomorrow I hope. I could
then send a list to the interested parties. Also, I gotta dig out that Z-19
and check it out. You wouldn't believe how much work I've got yet to get
that old house cleared out yet :( (I at least took time yesterday to
discuss Megan's 11/34A as it's just as important for me and my own 34A's
troubles plus I *really* needed a rest)
Anybody want to offer anything for this plus shipping from zip 14701? Will
be shipped in three or four cartons. Let me know.
Thanks much.
Regards, Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt(a)netsync.net
Member of Antique Wireless Association
URL: http://www.ggw.org/awa
