>Before that, most micros used off-the-shelf ICs. Although some of these
>chips are getting rather hard to find now -- some disk controllers
>(WD1771, Intel 8271, etc) are _very_ difficult to find new.
Not all are that difficult - BG Micro ( http://www.bgmicro.com/ ), for
example, has a fairly decent selection of WD floppy controller chips.
While on the topic of replacing "classic" VLSI chips, are there any
FPGA's still available in 40-pin packages anymore? I've seen PGA-to-DIP
adapters, but those are a bit clunky (and overkill!)
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
On Monday, September 27, 1999 12:10 PM, Bill Yakowenko
[SMTP:yakowenk@cs.unc.edu] wrote:
> One of the first things to do when you have a screenful of the
> wrong characters is to whip out an ASCII chart, and look at the
> binary codes for the characters you've got vs. the ones you
> expected. Very often the problem is a single-bit change, which
> narrows down the source of the problem. For instance, the
> difference between upper- and lower-case ASCII characters is a
> single bit.
>
> Cheers,
> Bill.
>
>
> On Sat, 25 Sep 1999, Gareth Randall <gwr(a)easynet.co.uk> wrote:
> ] Hi guys,
> ]
> ] I'm new here, so be gentle! =;-)
> ]
> ] I'm hopefully about to acquire a PET 8032 - the first PET I've ever owned
> ] (I was six years old when they first came out). I'm told that it boots into
> ] Basic 4.0, but the boot details are shown in lower case with the odd
> ] incorrect character. Also, when typing, some characters come up on the
> ] screen differently to the ones actually typed.
> ]
> ] The vendor suggests it may just need a clean and the I/O chip re-seating -
> ] but if it's something more complicated, is it still possible to buy
> ] replacement chips? And, thinking longer-term, are replacement screens
> ] possible to find these days (e.g. are they a standard size that you can
> ] still buy off-the-shelf)?
> ]
> ] Any suggestions gratefully received!
> ]
> ] Gareth
>
>
For the 8032, you'd need a "PETSCI" chart - Commodore didn't adhere completely
to the ASCII standard coding. I have a copy of the PETSCI codes, but they're at
home, and I'm not. If anyone needs them, e-mail me and I'll be happy to send
them to you, or post them.
Mark.
>If you don't eliminate non-authorized access to the hardware, then how
>could you eliminate non-operator use of the control panel? A
>non-operator could merely bypass the lock, or replace it with their own.
>Or is it merely intended to be a polite request and reminder?
Merely a polite request and reminder. On the DEC and DG machines,
you could put the lockswitch into the "panel lock" position, so that
folks brushing up against the front panel switches won't halt/crash the
machine.
>ANY properly designed and installed lock must be unlocked before it can be
>removed.
Sure. But if you've got physical access to the computer in the first
place, any hopes of true security are gone anyway. A hard disk lobotomy
(even easier for old removable pack drives than modern machines) gives
anyone access to your data, and they don't even have to be near the
front panel to do that!
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Greetings!
We just acquired a S/36 5363 III sans maintenance key, maint. diskettes,
manuals, in short we just got the CPU. Our main concern is opening the
case! We'd rather not drill out the lock (as some PS/2s have suffered)
if at all possible.
Any help and/or maint. materials are much appreciated!
Please reply to msg(a)waste.org
Thanks much!
Michael Grigoni
Cybertheque Museum
--- allisonp(a)world.std.com wrote:
> No scan or copy capability. The unit I was woking with required a
> resistor from the video ouput to ground, I'd picked 75ohms for the
> purpose.
Everything I've seen is like the basic 1861 design in the Elf-II article in
P-E: http://www.infinet.com/~erd/retrocomputing/ElfII/ (10K resistor on
SYNC, 2K resistor on VIDEO, tied together and to ground by 1K resistor).
Perhaps I just need to play with the resistor values.
> I'd have to see the circuit you have to figure it out. there were several
> variations.
It's the standard COSMAC VIP. I'll scan the 1861 output section and post
a URL for it later tonight if I get the chance. IIRC, it looks just like
the Elf-II circuit. Nothing complicated.
-ethan
=====
Infinet has been sold. The domain is going away in February.
Please send all replies to
erd(a)iname.com
__________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com
The 1770 and 1772, which were 28-pin IC's intended for use only with 5-1/4"
drives, the primary difference between them being the step rates they
support, were not widely used. I have the 1770 on my AMPRO "Little Board"
but the numbers are out of sequence in the sense that the first of their
parts was the 1771, followed by the 179x series, with a shot at a 178x group
( intended to fill the gap with respect to M^2FM and (?) hard sectors )
which wasn't around long if at all. The 1791 was an inverted-bus version of
the 1793. This inverted bus was inherited from the1771, and was designed to
explout the benefit of the inverting bus' slightly shorter propagation
delays.
One advantage the 1770/72 offered was that they had drivers capable of
driving the 110-ohm terminated cable to the drives.
Shortly after they released the 1770/72, they started making boards for IBM
and compatibles, which either used all their production of the required
parts, or made them sufficiently unpopular with their former customers now
competitors that they stopped making these parts, among others. They did
make a couple of 765-compatible FDC's with cable-driving outputs which
appeared on some of their SCSI HDC's and their IBM-compatible boards.
I've only got one spare, and I'm hoping I don't need that. If you find
these, please let me know.
Dick
-----Original Message-----
From: Glenatacme(a)aol.com <Glenatacme(a)aol.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Sunday, September 26, 1999 8:26 PM
Subject: floppy controller IC (was Re: Fixing a PET?)
>In a message dated 09/25/1999 2:53:45 PM Eastern Daylight Time,
>CLASSICCMP(a)trailing-edge.com writes:
>
>Tony Duell wrote:
>> >Before that, most micros used off-the-shelf ICs. Although some of these
>> >chips are getting rather hard to find now -- some disk controllers
>> >(WD1771, Intel 8271, etc) are _very_ difficult to find new.
>>
>
>CLASSICCMP(a)trailing-edge.com replied:
>> Not all are that difficult - BG Micro ( http://www.bgmicro.com/ ), for
>> example, has a fairly decent selection of WD floppy controller chips.
>
>This looks like a pretty good source. However, they don't list the WD1770
>disk controller IC -- anyone know where these might be available?
>
>TIA,
>
>Glen Goodwin
>0/0
One of the first things to do when you have a screenful of the
wrong characters is to whip out an ASCII chart, and look at the
binary codes for the characters you've got vs. the ones you
expected. Very often the problem is a single-bit change, which
narrows down the source of the problem. For instance, the
difference between upper- and lower-case ASCII characters is a
single bit.
Cheers,
Bill.
On Sat, 25 Sep 1999, Gareth Randall <gwr(a)easynet.co.uk> wrote:
] Hi guys,
]
] I'm new here, so be gentle! =;-)
]
] I'm hopefully about to acquire a PET 8032 - the first PET I've ever owned
] (I was six years old when they first came out). I'm told that it boots into
] Basic 4.0, but the boot details are shown in lower case with the odd
] incorrect character. Also, when typing, some characters come up on the
] screen differently to the ones actually typed.
]
] The vendor suggests it may just need a clean and the I/O chip re-seating -
] but if it's something more complicated, is it still possible to buy
] replacement chips? And, thinking longer-term, are replacement screens
] possible to find these days (e.g. are they a standard size that you can
] still buy off-the-shelf)?
]
] Any suggestions gratefully received!
]
] Gareth
Have you tried http://www.ewanted.com/ ?
It's free - you never know!
Neil
> -----Original Message-----
> From: Francisco Morales [SMTP:pacomo@execpc.com]
> Sent: Friday, September 24, 1999 1:39 PM
> To: Discussion re-collecting of classic computers
> Subject: Looking for a grundy NEWBRAIN
>
> I am looking to buy a NEWBRAIN. It was my first computer and I have been
> searching the web for some time and haven't found any.
> Anyone has one for sale?
>
> Paco
I am forwarding this to classiccmp(a)lists.u.washington.edu
Neil Morrison
email:morrison@t-iii.com
> -----Original Message-----
> From: Bob Carner [SMTP:rscarner@VT.EDU]
> Sent: Monday, September 27, 1999 4:41 AM
> To: HEATH(a)LISTSERV.TEMPE.GOV
> Subject: FS: H-89A Computer
>
> Anyone interested in an Heathkit H89A computer?
> Bob Carner
>
> Bob Carner, EE, SysAdmin, and Network Liason
> Brooks Forest Products Center
> Department of Wood Science and Forest Products
> rscarner(a)vt.edu
>
> Sponsored by the City of Tempe
>
> Listserver Submissions: heath(a)listserv.tempe.gov
> Listserver Subscription: listserv(a)listserv.tempe.gov - "subscribe heath
> 'name' 'call'"
> Listserver Unsubscribe: listserv(a)listserv.tempe.gov - -"signoff heath"
Greetings!
Just acquired a Sun 3/50; it is diskless and boots on tftp. We're
hoping
to find SunOS .LE. 4.1.1 or Solaris .LE. 2.3 to demonstrate it (and
other
Sun 3 hardware).
All replies much appreciated (msg(a)waste.org)
Thanks.
Michael Grigoni
Cybertheque Museum
