Stan Smith writes:
> I have an early Radio Shack TRS80 L1 computer. I bought it new in the
> late seventies. I got it out of storage the other day to show my
> students and found that the horiziontal synch wasn't working. I am
> looking for a schematic to fix . Can you help me out?
There's a scan of the schematics from the tech manual at
http://incolor.inetnebr.com/bill_r/trs80_schematics.htm
--
Tim Mann tim(a)tim-mann.org http://tim-mann.org/
I acquired a PAIA PVI-1 circuit board yesterday, and a Google search
brings up no information about this board. The main chip seems to be a
GI 2513 with some 8 7400 and CMOS support chips. On the circuit board
are two RCA jacks labeled TV and VID, two pots labeled "H POS V", a
jumper for selecting 32 or 64, and another YES or NO jumper for the
cursor. The code date on some of the chips are in the 1977 era. Does
anyone know what this thing is, and does anyone have any docs?
In the haul I picked up last week, one of the advertised VT-100s turned
out to be a VT-103 and I am beginning to suspect ... with John's help :)
... that the dual 8" RX02 drives go to this unit. No software but it
looks like an interesting find!
I just recieved a few DECmate III "motherboards" which are supposedly
functional (the guy is selling more of them on eBay right now, for
their Intersil 6120 chips). Before I attempt to desolder the chip,
does anyone have information on these things? I'm looking for
information on what each of the connectors is, and the pinout of the
power connector (J2) and kb/video connector (J5?). Also, any manuals
or images of software disks for this thing would be nice : ).
Here's what the connectors are labelled on my board:
J1 and J? (can't see a label for that one) are 34pin headers, and I'm
guessing go to RX50s, J3 is probably the 'expansion connector', J6 and
J4 are serial(?) and J5 is the video/kb (?). I'm fairly certain that
J2 is power, but don't know what its pinout is without playing with my
DMM... but I'd rather get it right the first time and *not* smoke the
board...
Btw, J? hangs off of the side of the board, and is a right-angle header,
unlike all the rest of the connectors.
+------------------------------------------+
| ______J6______ ____J5____ ___J4__ |
| \___DB25P____/ /___DA15P__\ \_DE9P/ |
| _____________ +-+ |
| |__34pin hdr__| |'| |
| J1 |:| |
| |:|J|
| |:|2|
| |:| |
| +------------+ +-+ |
| | | +--+
| | E30 | | |
| | DC382 | | |J?
| | | | |
| +------------+ | |
| +--+
| +------------+ __ |
| | | | | |
| | E25 | | | |
| | DC381 | ___ | |J|
| | | | 6 | | |3|
| +------------+ | 1 | | | |
| | 2 | | | |
| | 0 | |_| |
| |___| |
| |
+------------------------------------------+
--
Purdue University ITAP/RCS
Information Technology at Purdue
Research Computing and Storage
http://www.itap.purdue.edu/rcs/
On 11/17/2003 12:07 PM -0600, Mark Tapley <mtapley(a)swri.edu> wrote:
>Date: Mon, 17 Nov 2003 09:56:36 -0600
>Subject: Dec Rainbow prehistory
>
>Tom Jennings wrote:
> >(I was the one who ported MSDOS to the DEC Rainbow 100A, I
> >could tell you some terrible DEC stories... :-(
>
>Oh, *that* Tom Jennings! I wasn't paying adequate attention. Your
>name is all over the "useful people to know if you own a Rainbow"
>documentation I have (Yes, I own a 100A, 8087 adaptor, 832k RAM, Hard
>drive board and an ST-225 (I think?) in it right now.)
>
>Welcome!
<snip>... similar light dawns over marblehead...
I was just realizing that I gave away probably my only installed copy of
the RX50.DRV shim the other month... This was an MS-DOS device driver that
remapped the standard HD 5.25" drive to be Rainbow RX50 compatible.
Does anyone have this or something like this that works with current MS-DOS?
(or even old DOS versions, I could boot an old version to just copy files)
I have a bunch of RX50s lying around I should look at before disposing of...
Dave (former Mr. DECnet-DOS).
I've got this 3Com OfficeConnect Dual Speed Hub 8 that is putting out this
obnoxious hissing noise. It's loud enough to be annoying and add
significantly to the white noise in my office. It sounds like the air is
slowly being let out of a tire...forever. I've opened it up and found a
capacitor with some brownish crusty stuff caked on the top of it. It also
was bulged ever so slight at the top, as was another one right by it.
Both are within proximity of the power connector. I didn't see any
blackened spots on the enclosure indiciating that either had let out any
magic smoke.
So the question is, what is the most likely cause for this hissing? I've
had a device before where the capacitor was causing the hiss (or at least
I was pretty sure). There doesn't seem to be anything else in there that
would cause the hissing (a bunch of ICs, a couple couls, a couple power
transistors, etc.)
Any help appreciated.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
For those who may be interested, I'm selling an original DOS 1.00 Disk on
E-bay this week. The E-bay auction number is 2767991821. The item is titled
"MS-DOS Version 1.00 Original 1981 Disk " The auction expires Nov. 29 at
23:30 EST. The current bid is US$300.
Thank you.
Ron
ChromTech still stocks paper for the HP85 - their part number CTP-3390.
Price was $22.25 a roll which should last a _long_ time. Website at
www.chromtech.com . Sure makes a difference to use the fresh stuff!
Jack Rubin
Wilmette, Illinois
USA
der Mouse wrote:
> ["Brian L. Stuart" <blstuart(a)bellsouth.net>]
>> Now here I do agree with the desire to define a computer in terms of
>> machines that can compute functions that are computable in a
>> Church-Turing sense.
>
> Hm, so you consider "analog computer" to be an oxymoron?
Certainly not an oxymoron. I have a real soft spot for analog
computers. The theorist in me wants to hear the term analog
computer as a whole as describing a computing device in a different
class from the sort we've been discussing. A part of me kind
of wishes a different term had been adopted for these machines,
but differential equation engine just doesn't have the same ring.
Now if I had just had a way to rescue the EIA hybrid machine I
used in college. Of course, I'd have no place to put it, but
we can ignore minor details like that...
Brian L. Stuart
Hi Ran,
I just wanted to follow up and ask you if you still have a Currah
Speech Messenger cart for the C-64 left. I've been looking for one on
eBay and I never seem to be able to get my hands on one. Please let me
know if you have one available or not, and if you do, I can send
payment via PayPal. Thank you for your time!
Sincerely,
Tony
