any thoughts? And although he claimed the 2000 never
generated a NMI, won't a parity error always do this?
Irrelevant maybe cuz that's a catastrophic fault
thing, not something typically encountered...
Maybe he provided more details, but I'm tired...
> > I was working on a mod, never completed, for the
T2K
> > that would make it
> > after the O/S was loaded, 100% PC-compatible.
> > Required 1 hardware chip,
> > and a customized IO.SYS. Whereupon any DOS
> > application would run on the T2K,
> > even stuff doing serial-port manipulation, direct
> > video-memory writes, DMA,
> > etc.
The one-chip mod was a PAL that monitored the address
lines from the
CPU,
when It saw an I/O instruction in 'low' address-space,
it generated an
NMI (not used at all by the T2K), then the software
service routine
for NMI unwound the stack to find the offending I/O
instruction, and
re-mapped the "PC" functionality to the T2K hardware.
Coupled with a
timer-tick 'refresh' routine that copied data from "PC
video memory" to
the T2K video memory (remapping attributes, etc. as
required.)
The chip actually had 2 modes of operation -- NMI
active, as described
above, and 'NMI inactive', where it pretty much did
nothing -- except
listen for the 'magic words' that made it go active,
that is. :) This
enable/disable mode switching was necessary, to allow
"T2K DOS"
internals
(and/or the 'sofware service routine) to access the
T2K hardware
directly.
____________________________________________________________________________________
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> At 09:46 AM 7/1/2007, Scott Quinn wrote:
>> For a brief period, NewTek did have a Macintosh clone with a 68030
>> and system software that was a hybrid of System 6 and System 7,
>
> "NewTek" was an Amiga company, "NewTech" was the Mac clone company.
>
> - John
Hmm-the reviewer in the magazine I have must have had spell-check on,
as it came out "NewTek Duet" every time.
Explains why I couldn't find much else on it.
Greetings,
I am new to this group, so I hope that I am doing this correctly.
I have a bunch of computer parts looking for a new home, many are from
vintage computers. Most of the initial things I have posted are S-100 PCBs
(memory, I/O, interfaces,...), many of which include documentation, and some
even include software. I also have a NorthStar Horizon chassis (including
linear P/S, motherboard, but no top cover or drives). There are other items
as well, including a VME chassis; and I expect to have several Heathkit
items posted soon. Unless specified, I believe that all of these items were
operational prior to being boxed (several years ago), and still appear to be
in good condition.
I am enquiring with several people I have found on the Web, hoping to find
one or more interested parties. I have considered posting them on eBay; but
thought that I'd offer them directly first.
These items are located in Southern California; so shipping outside that
area may be a (minor) concern (for larger or heavier items). At the very
minimum, I am interested in recovering the cost for S/H; but would prefer to
get a bit more to help with my purchasing a new laptop.
I have set up a temporary Yahoo Group to help with showing and describing
the items; that way, it won't impact the bandwidth of sites such as this
one. The Group is called "Verns_Stuff"
(http://groups.yahoo.com/group/Verns_Stuff). If you have any interest in
S-100, VME, or Heathkit computer items, please drop by.
If you are not interested, but you are aware of other individuals or groups
that might be, please feel free to forward this information on to them.
Thank-you.
Vern.
>
> From: "Mike Hatch" <mike.hatch at mclennan.co.uk>
>
>> Its got Ampex
>> TM4 mag tape drives (not industry standard 7 or 9 track, these are
>> ten track units with hubs the same design as professional audio
>> tapes
>> and the 2 and 3 inch wide video tapes once used by TV broadcasters).
>
> Our SDS9300 had TM4 drives but I don't remember them being 2 and 3
> inch
> wide, I thought they were 0.5 inch, but then that was 35years ago.
Yes they are half inch. What I meant was that they are not 'industry
standard' half inch tape with large expanding hubs with the write
protect ring in a groove in the reel. Instead the centres are much
smaller, allowing 3200 feet on the same outside diameter spool as a
2400 foot reel using the same thickness tape (not the ultra thin
tape). The reels are aluminium, not plastic, their centres have three
notches which three matching 'fingers' within the hub fit into,
holding the reel onto the hub. Some TM4s were fitted with small
expanding hubs (the ones on the Leo and maybe others), but this did
not fit 'industry standard' reels. The same design of hub is used on
tapes of quarter inch, half inch, one inch, two inch and three inch,
maybe other sizes too. I do not mean domestic quarter inch tape
recorders, these use a simple nut on a stud. The write protect ring
protrudes from the back of the reel, and three projections on the
ring fit into three holes in the reel. The tapes themselves have a
metalised leader which is electrically sensed by the deck. They also
have a reflective early end of tape marker like later tapes, and I
think they have a metalised leader at the end of tape, though I've
never unreeled 3200 feet of tape to find out.
FYI:
Regards,
Andrew B
aliensrcooluk at yahoo.co.uk
rbernardo(at)iglou.com wrote: To: acug0447 at yahoogroups.com,auscbm at yahoogroups.com
From: <rbernardo at iglou.com>
Date: Sat, 30 Jun 2007 19:53:12 -0400
Subject: [acug0447] Fwd: Jim Butterfield passes away
--- Forwarded message ---
I regret to advise the Commodore community that Jim Butterfield has
passed away. Jim died at 1:30 AM on June 29 after battling cancer
which infected many parts of his body.
His family advises that there will not be a funeral as such but a
commemoration of Jim's life is planned in the next month or two.
At the moment that is all the detail that I have to report.
We have all lost a truly wonderful friend and teacher.
Ernie Chorny
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>
>Subject: Re: Drum vs. Core
> From: "Chuck Guzis" <cclist at sydex.com>
> Date: Fri, 29 Jun 2007 13:49:22 -0700
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>While the main store on the IBM 650, didn't most of the installed
>base (eventually) also have 50 words of core as sort of a
>"scratchpad" memory?
>
>Cheers,
>Chuck
This was common. The problem with rotating memory, mercury delay,
magnostrictive delay and even shift registers is they are not random
access they are sequential access They all have a fixed delay and you
wait for what you want to "come around". Programmers had to program
around that if speed was required.
Allison
> Now, of course, such an effort would be in violation of DMCA, but it
> worked back then. I'm surprised that no one did that with the Mac
> ROMs--anyone know why not?
Probably because they would also then need to clone the system software
as well, a much bigger task for a much smaller (potential) market.
Apple would have been much less likely to deal with clone makers than
Microsoft was. While the system software was made freely available in
the early years, it is unlikely it would have stayed that way if clone
makers had been successful.
For a brief period, NewTek did have a Macintosh clone with a 68030 and
system software that was a hybrid of System 6 and System 7, with a user
interface based on Motif. It suffered the same problems as the 1st -
gen IBM clones as far as compatibility.
On Fri, 29 Jun 2007, Brent Hilpert wrote:
> Indeed, according to http://www.columbia.edu/acis/history/650.html there was
> 60 words of core used as a buffer between the drum and tape drives to account
> for their different data rates, but which could also be used for other stuff.
Well, then you have to count the LGP-30 as computer with core memory, too,
because the interface to the (apparently extremly rare) magnetic tape drives
(yes, there were tape drives for the LGP-30!) contained core memory as buffer.
The drive would buffer the block in core so that the LGP-30 could read it with
its own speed (and vice versa).
Christian
Now that I have some more time to do it, I've listed some stuff on Ebay.
My name there is "frotz661".
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
