On Oct 1 2004, 11:06, Dwight K. Elvey wrote:
> Hi
> I'm looking for a spec sheet on a 8308. I think it
> is part of the older National Semi series DM8308.
> It might be a 8303 ( the schematic is not to clear ).
> I think it is an inverting 8 channel bus tranceiver.
> I need information on which way the drivers go with
> the direction control and is the enable true or false.
I think you mean DP8303 / DP8308? Both of these are 20-pin DIL 8-bit
bidirectional transceivers; the DP8303 is inverting and the DP8308 is
non-inverting. In both cases, the A port is pins 1-8, and the
corresponding B port pins are 19-12.
On the DP8303 (and DP8304, which is the non-invering equivalent) Chip
Disable (active high to disable) is pin 9; pin 11 is Transmit/-Receive;
"transmit" (pin 11 high) means A is input and B is output.
On the DP8308 (and DP8307, the inverting equivalent), pin 9 is
-Transmit and 11 is -Receive (both active low).
On all of them, port A can sink up to 16mA and port B can sink up to
48mA.
The DP7303/4/7/8 devices are extended-temperature range versions of
DP8303/4/7/8.
--
Pete Peter Turnbull
Network Manager
University of York
>From: "Bryan Blackburn" <oldcomp(a)cox.net>
>
>
>>>I may be whacked in the head, but what did the Poly 88 innovate other
>>>than cuteness? Or maybe that doesn't matter because it is has an s-100 buss?
>>
>> Actually it did provide a turning point in micro processors.
>> It was the first S-100 to have only a power and reset button on the front.
>> It had a monitor ROM built in that provided a display of memory and
>> registers, using the memory mapped video. The ROM also had the
>> tape read code built in. They'd have put the tape write code in
>
>->snip<-
>
>So. What I hear you saying, is that they were the first to copy the
>digital group...! :)
Is it S-100? When did they first come out?
Dwight
>
>-Bryan
>
>
Hello,
I have what appears to be an original loose-leaf
manual for NewDOS/80 (Apparat, Inc) for the TRS-80
model I computer system.
Manual only, no software.
Yours for shipping costs only - maybe $5.00.
Steve.
__________________________________
Do you Yahoo!?
New and Improved Yahoo! Mail - Send 10MB messages!
http://promotions.yahoo.com/new_mail
Right, I've gone and forgotten who looks after bitsavers.org - I know
it's one of you, anyone fancy owning up? :-)
cheers,
Jules
--
I'm sorry for all the times I intentionally ducked underneath the sneeze
guard at a salad bar and sneezed on everything until I couldn't sneeze
any more. I have a problem.
There was an HP3000/922 at MSU Salvage today, with what looked like
a disk cabinet (similar size and shape to the processor cabinet)
and some cables. No idea whether any of it works. No apparent
software or manuals. I may grab it on Friday if it's still there.
If it didn't sell today it should be safe until then, as that's the
next public sale day.
If anyone wants this thing, let me know. I have little enough time
and spare cubic volume in my life without adopting machines I know
nothing about. Someone who already loves this family would make it
a better home.
De
>From: "Joe R." <rigdonj(a)cfl.rr.com>
>
>At 04:14 PM 9/30/04 -0700, you wrote:
>>>From: "Bryan Blackburn" <oldcomp(a)cox.net>
>>---snip---
>>>
>>>I may be whacked in the head, but what did the Poly 88 innovate other
>>>than cuteness? Or maybe that doesn't matter because it is has an s-100 buss?
>>
>>Hi
>> Actually it did provide a turning point in micro processors.
>>It was the first S-100 to have only a power and reset button on the front.
>>It had a monitor ROM built in that provided a display of memory and
>>registers, using the memory mapped video. The ROM also had the
>>tape read code built in. They'd have put the tape write code in
>>it as well but that was all they could squeeze into the 1K EPROM.
>>The tape was capable of both Byte format and a high speed ( I forget
>>if it was 9600 or 4800 ). To write to the tape, one could enter
>>the program through the monitor. Of course, it made sense to save
>>that program as your first tape program.
>
> OK so what's the big deal? Intel had all of these features in their
>MDS-800s (and maybe in their earlier Intellecs, I don't know). The MDS was
>Multibus but that's no big deal.
>
>
>
> The Poly88 had its problems.
>>cooling was a big issue.
>> I have two of these, fully operational :)
>
> I think I have NINE MDSs all functional :-)
>
> Joe
>
Hi Joe
The monitor on the MDS800 isn't as good as the Poly's, it isn't
S-100 and it has 8 switches on the front, other than power. Although,
only one of these switches it needed to get to the monitor.
The display is not memory mapped so you don't get the same richness
of information in depth or in speed.
Then, the 800 was designed to solve different problems.
Dwight
>From: "Bryan Blackburn" <oldcomp(a)cox.net>
---snip---
>
>I may be whacked in the head, but what did the Poly 88 innovate other
>than cuteness? Or maybe that doesn't matter because it is has an s-100 buss?
Hi
Actually it did provide a turning point in micro processors.
It was the first S-100 to have only a power and reset button on the front.
It had a monitor ROM built in that provided a display of memory and
registers, using the memory mapped video. The ROM also had the
tape read code built in. They'd have put the tape write code in
it as well but that was all they could squeeze into the 1K EPROM.
The tape was capable of both Byte format and a high speed ( I forget
if it was 9600 or 4800 ). To write to the tape, one could enter
the program through the monitor. Of course, it made sense to save
that program as your first tape program. The Poly88 had its problems.
cooling was a big issue.
I have two of these, fully operational :)
Dwight
> wanted a TTL based computer, I'm thinking about
> building the Educ-8, http://www.ljw.me.uk/educ8/ , a
> similar TTL based machine described in an electronics
> australia article in 1975. Amazingly, they still sell
> the boards for it, or at least in theory they do, I've
I managed to collect the original magazines with the Educ-8 articles as
well as scans of the articles, and although the boards are available I
am not sure they would all that useful. The Educ-8 was designed around
both 74 and 8 series TTLs. I did some cross referencing, but could not
locate datasheets on all the 8 series ICs used, so I am not 100% certain
that there are pin equivalent 74 series ICs for all. This might mean a
board reroute.
David
>From: "ben franchuk" <bfranchuk(a)jetnet.ab.ca>
>
>Peter C. Wallace wrote:
>> Isn't self modifying code pretty much deprecated these days (aside from
>> trampolines and such)
>
>
>So what is a trampoline?
>> Peter Wallace
>
>
> I have yet to see a good use for self-modifying code. Other than
>subroutines and interupts placing data into a code segement the only
>self modifying code I have seen was for the 8088.
>Ben.
>
Hi
It is interesting that different people have different ideas
as to what self modifying code is. Actually, the ability to
load code and execute from a mass storage is self modifying.
Code that uses a variable value for a table to look up execution
addresses is self modifying. Most every multitasking system
I've seen are self modifying.
I think what people consider dangerous self modifying is
when the program alters the actual execution instructions in
memory and then executes them. It is strange that this form
gets such a large amount of emotional negative response while
other types are hardly considered issues.
No matter how the code is written, one can make bad code in
most any form. One can also make good code as well. There is
no reason why self modifying code should be any more dangerous
than any other type of coding if done with a complete understanding
of what the limitations are. What is the difference between
replacing one or two instructions and then executing them or
replacing an overlay and then executing that overlay? Other
than size, both are doing the same thing. One is forbidden
while the other is normal operation.
Dwight
