Hi
The zener is only needed if the keyboard you intend to
use needs a negative rail. Normally most would need
a 12 volt zener but some need a -15 volt level.
You need to check the current of the keyboard to determine
the right value for the resistor.
As Randy states, the manual is available now. The keyboard
is intended to be connected through this board and this
board has a connection to one of the interrupt lines.
The keyboard is to be a parallel out, 8 bits, w/ + or - strobe.
It has memory mapped video with either characters ( including
Greek ) or block graphics. The output is standard composite
video.
If you ever want to get it working, you can contact me
and I can most likely help you some.
Dwight
>From: "Randy McLaughlin" <randy_at_s100-manuals.com>
>
>----- Original Message -----
>From: <Saquinn624_at_aol.com>
>To: <cctalk_at_classiccmp.org>
>Sent: Monday, December 27, 2004 12:38 PM
>Subject: S-100 Polymorphic Systems card questions
>
>
>> I have a S-100 based system that seems to mostly run, but I have some
>> questions on the video card.
>> It is a Polymorphic Systems card, but looks different from all the
>> examples I
>> could find on the internet
>>
>> Markings are: Polymorphic Systems (c) 1976 I.P.C VIDEO rev 0.0, with most
>> chips aligned vertically
>>
>> The keyboard? port is a 14 pin DIP socket in the upper R.H. corner, next
>> to a
>> 8212 I/O chip.
>> Between this and the VIDEO marking, there are some pads with heat damage
>> that
>> have the symbol for Zener diode across one of them. I have no idea what
>> the
>> component specs are for these pads.
>>
>> Also, 2 questions: does anyone have the DIP switch settings table for this
>> card? 7 switches, currently set at 1 1 1 1 0 0 0
>>
>> and (2) the 8212 interface makes me think that the keyboard is some sort
>> of
>> parallel interface, but the computer came with a DIP header connected to 3
>> wires
>>
>> (bonus question: this card has some jumper wires and a resistor soldered
>> on
>> the trace side of the PCB, is this official, or is this a hack? the joints
>> look
>> sort of "hacky" the resistor goes between +Vcc and pin 20 of the 6571AL,
>> the
>> jumpers are between some of the 74XXX gates on the L.H. side of the card
>> [where the 7805 V.R. is])
>>
>> found it at my church garage sale several years ago, so I can't "ask the
>> owner"
>>
>> Scott Quinn
>
>
>You can find the manual for it on my website:
>
>http://www.s100-manuals.net/Harte-manuals/PolyMorphic/index.html
>
>
>Randy
>www.s100-manuals.com
>
>
>
Received on Sun Jan 02 2005 - 19:09:28 GMT