[N8VEM: 20200] respin of SBC-188 board

[John Coffman]

Todd has been sold-out of the SBC-188 (rev. 2) board for some time now,
and I did not know whether interest in the board had waned or whether a
re-spin was in order.

AFAIK, the present board has only one issue, a clearance problem in
mounting a SuperCap to the board. To fix this issue, a new drill mask
would be needed, and this incurs the full engineering charge by the
manufacturer. So if this issue is addressed, it might be time to
consider several other updates:

1. Address the SuperCap clearance issue.
2. Technical change to memory selection: use /A19 to select low
512K memory, freeing up the Middle Select to allow programming wait
states for the VGA and 4MEM address ranges. Low Select still unused; no
change to High Select for ROM.
3. Change UART to PLCC to save space.
4. Change MAX232 to 233 to eliminate caps, possible space saving.
5. Change DTR/DSR output to RTS/CTS. PLCC -550C UART can do latter
in h/w.
6. Add an IDE connector in one of two ways:
a. Change PIO 26-pin connector to PPIDE 40-pin connector at
board edge.
b. Eliminate 8255 completely, and go to 8-bit IDE interface
like the Mark IV.
Does anyone use the 8255 for anything other than PPIDE through a
daughter board?
7. Change interrupt connection so /INT better supports the keyboard
on the CVDU or (future) VGA board.

The SBC-188 is a very dense board; changes that use less board space are
easy; changes that use more board space may not be possible.

Any comments or further ideas would be appreciated.

--John

[Wayne Warthen]

Hi John,

I would be interested in such a respin. You captured my wish list pretty
well and I would vote for a dedicated IDE interface instead of the PPI.

--Wayne

Post by John Coffman
Todd has been sold-out of the SBC-188 (rev. 2) board for some time now,
and I did not know whether interest in the board had waned or whether a
re-spin was in order.
AFAIK, the present board has only one issue, a clearance problem in
mounting a SuperCap to the board. To fix this issue, a new drill mask
would be needed, and this incurs the full engineering charge by the
manufacturer. So if this issue is addressed, it might be time to
1. Address the SuperCap clearance issue.
2. Technical change to memory selection: use /A19 to select low
512K memory, freeing up the Middle Select to allow programming wait
states for the VGA and 4MEM address ranges. Low Select still unused; no
change to High Select for ROM.
3. Change UART to PLCC to save space.
4. Change MAX232 to 233 to eliminate caps, possible space saving.
5. Change DTR/DSR output to RTS/CTS. PLCC -550C UART can do latter
in h/w.
a. Change PIO 26-pin connector to PPIDE 40-pin connector at
board edge.
b. Eliminate 8255 completely, and go to 8-bit IDE interface
like the Mark IV.
Does anyone use the 8255 for anything other than PPIDE through a
daughter board?
7. Change interrupt connection so /INT better supports the keyboard
on the CVDU or (future) VGA board.
The SBC-188 is a very dense board; changes that use less board space are
easy; changes that use more board space may not be possible.
Any comments or further ideas would be appreciated.
--John

[Fabio Battaglia]

Interested in a respin too!
Fabio

Post by Wayne Warthen
Hi John,
I would be interested in such a respin. You captured my wish list pretty
well and I would vote for a dedicated IDE interface instead of the PPI.
--Wayne

Post by John Coffman
Todd has been sold-out of the SBC-188 (rev. 2) board for some time now,
and I did not know whether interest in the board had waned or whether a
re-spin was in order.
AFAIK, the present board has only one issue, a clearance problem in
mounting a SuperCap to the board. To fix this issue, a new drill mask
would be needed, and this incurs the full engineering charge by the
manufacturer. So if this issue is addressed, it might be time to
1. Address the SuperCap clearance issue.
2. Technical change to memory selection: use /A19 to select low
512K memory, freeing up the Middle Select to allow programming wait
states for the VGA and 4MEM address ranges. Low Select still unused; no
change to High Select for ROM.
3. Change UART to PLCC to save space.
4. Change MAX232 to 233 to eliminate caps, possible space saving.
5. Change DTR/DSR output to RTS/CTS. PLCC -550C UART can do latter
in h/w.
a. Change PIO 26-pin connector to PPIDE 40-pin connector at
board edge.
b. Eliminate 8255 completely, and go to 8-bit IDE interface
like the Mark IV.
Does anyone use the 8255 for anything other than PPIDE through a
daughter board?
7. Change interrupt connection so /INT better supports the keyboard
on the CVDU or (future) VGA board.
The SBC-188 is a very dense board; changes that use less board space are
easy; changes that use more board space may not be possible.
Any comments or further ideas would be appreciated.
--John
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[Brian Marstella]

Good afternoon, John,

While I don't really need another project, I'd be interested in getting one
of the boards if the pricing comes in around $20 to $30 plus shipping; more
than that and it might be a budget problem.

Regarding the changes, the SD card was my biggest issue although I like the
idea of an IDE connector directly supported. I like the idea of switching
to the 233 as well to eliminate components.

The other ideas look good. Thanks for heading this up.

Regards, Brian.

[John Coffman]

Post by Brian Marstella
Good afternoon, John,
While I don't really need another project, I'd be interested in
getting one of the boards if the pricing comes in around $20 to $30
plus shipping; more than that and it might be a budget problem.
Regarding the changes, the SD card was my biggest issue although I
like the idea of an IDE connector directly supported. I like the idea
of switching to the 233 as well to eliminate components.
The other ideas look good. Thanks for heading this up.
Regards, Brian.

Brian,

We can hold the board price to $20 for the 2-layer board. All previous
rev's are 2 layers.

--John

[John Coffman]

Yes, please! Give a late starter a chance to build this impressive SBC!
A dedicated IDE-interface would be great.
--Jonas

I'm pleasantly surprised at the response to the idea of the dedicated
IDE port. You all do know, that like the Mark IV, the dedicated IDE
port is an 8-bit port. I know of no Compact Flash cards that do not
support 8-bit I/O. On the other hand, I know of no hard disk that
supports 8-bit transfers; all are 16-bit.

I have the feeling that the IDE-8 i/f on the Mark IV has been a success.

Question: is the 8255 expendable? Eliminating it would free up a lot
of board real estate, and would make board layout a lot easier. Except
for its use for PPIDE, is anyone using the 8255 for other purposes?

--John

[Wayne Warthen]

I would say the 8255 is expendable. I have not heard of anyone using it
for anything other than an IDE adapter. The 8-bit constraint is not much
of a concern unless you specifically want to use a "real" hard disk, and
have not heard of anyone doing that either. Essentially, this is saying
that the board should have a connector intended specifically for a CF card
via a CF-IDE adapter.

One question related to the orientation of pin 1 on the ide connector
though... I like having the flexibility of mounting a CF adapter so that
it either extends out from the board footprint OR so that it doubles back
on the board foot print. This is possible if the IDE connector is oriented
with pin 1 down (when looking at the top (component side) of the board with
the ECB connector on the right). This allows you to install a 270 degree
CD-IDE adapter so that the CF card doubles back on the board. Alternately,
you can still use a right-angle IDE connector and have the CF card extend
out from the board.

I have attached a picture of the 270 degree adapter with CF card doubled
back over the board from a SCIS2IDE board to illustrate what I mean.

Thanks,

Wayne

Post by John Coffman

Yes, please! Give a late starter a chance to build this impressive SBC!
A dedicated IDE-interface would be great.
--Jonas

I'm pleasantly surprised at the response to the idea of the dedicated
IDE port. You all do know, that like the Mark IV, the dedicated IDE
port is an 8-bit port. I know of no Compact Flash cards that do not
support 8-bit I/O. On the other hand, I know of no hard disk that
supports 8-bit transfers; all are 16-bit.
I have the feeling that the IDE-8 i/f on the Mark IV has been a success.
Question: is the 8255 expendable? Eliminating it would free up a lot
of board real estate, and would make board layout a lot easier. Except
for its use for PPIDE, is anyone using the 8255 for other purposes?
--John

[John Coffman]

[Wayne Warthen]

Wayne,
Some CF card adapters allow 2 CF cards to be inserted, one on the front
(IDE master) and one on the back (IDE slave). With the adapter you are
using in the photo, is there space on the back for a slave CF card?
Any IDE connector orientation allows the CF adapter to stick up at right
angles to the N8 board. With pin 1 oriented as used on the MF/PIC & Mark
IV boards, use of a right-angle IDE connector allows a 2-sided adapter to
extend upward almost in the plane of the board. (see MF/PIC in background
of photo).
I hope others will weigh in on this orientation issue.
--John
Hi John,

Yes, use of a 270-degree adapter would preclude the use of a slave CF card.
In my 270-degree adapter, there is no CF card slot on the back at all. In
fact, I don't think I have ever seen a 270-degree adapter with both the
master and slave sockets.

Not sure I followed your comment about the way the current orientation
helps keep the adapter in the plane of the host board. I took a couple
photos using the Mark IV. In one, the CF adapter is in the current,
working orientation (photo called "as-is"). In the second photo
("proposed") I have flipped the CF adapter. As far as I can see, there is
no difference in the alignment of the space used. Only difference I note
is the LEDs being on the "back" side.

One more thing I have found that I like about the proposed orientation is
that I seem to be able to find shrouded right-angle adapters that work. In
the as-is orientation, I cannot seem to find a suitable shrouded
right-angle adapter. As you know, I am a big fan of shrouded connectors
because they keep me from doing stupid things...

Anyway, all this is not a big deal. I don't feel strongly about this.

Thanks,

Wayne

[Wayne Warthen]

Oops, forgot the photos... Here they are.

Post by Wayne Warthen

Wayne,
Some CF card adapters allow 2 CF cards to be inserted, one on the front
(IDE master) and one on the back (IDE slave). With the adapter you are
using in the photo, is there space on the back for a slave CF card?
Any IDE connector orientation allows the CF adapter to stick up at right
angles to the N8 board. With pin 1 oriented as used on the MF/PIC & Mark
IV boards, use of a right-angle IDE connector allows a 2-sided adapter to
extend upward almost in the plane of the board. (see MF/PIC in background
of photo).
I hope others will weigh in on this orientation issue.
--John
Hi John,

Yes, use of a 270-degree adapter would preclude the use of a slave CF
card. In my 270-degree adapter, there is no CF card slot on the back at
all. In fact, I don't think I have ever seen a 270-degree adapter with
both the master and slave sockets.
Not sure I followed your comment about the way the current orientation
helps keep the adapter in the plane of the host board. I took a couple
photos using the Mark IV. In one, the CF adapter is in the current,
working orientation (photo called "as-is"). In the second photo
("proposed") I have flipped the CF adapter. As far as I can see, there is
no difference in the alignment of the space used. Only difference I note
is the LEDs being on the "back" side.
One more thing I have found that I like about the proposed orientation is
that I seem to be able to find shrouded right-angle adapters that work. In
the as-is orientation, I cannot seem to find a suitable shrouded
right-angle adapter. As you know, I am a big fan of shrouded connectors
because they keep me from doing stupid things...
Anyway, all this is not a big deal. I don't feel strongly about this.
Thanks,
Wayne

[John Coffman]

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Wayne,<br>
<br>
I recall going through the "orientation" argument with myself back
when the MF/PIC board was laid out.&nbsp; The only right angle shrouded
headers I could find orient the CF adapter with the CF cards and
indicator LEDs facing backward.&nbsp; I thought this orientation to be
very unnatural.<br>
<br>
I don't particularly like the bare (unshrouded) right angle headers,
but forward facing orientation won out.<br>
<br>
If a straight-thru&nbsp; header is used, shrouded or not, then the
indicator LEDs and CF card face toward the center of the board.<br>
<br>
--John<br>
<br>
<br>
<br>
<br>
&nbsp;On 10/11/2015 06:57 PM, Wayne Warthen wrote:
<blockquote
cite="mid:ebd1a646-02d2-435b-9b7f-***@googlegroups.com"
type="cite">
<div dir="ltr">Oops, forgot the photos... &Acirc;&nbsp;Here they are.
<div><br>
</div>
<div><br>
<br>
On Sunday, October 11, 2015 at 6:55:52 PM UTC-7, Wayne Warthen
wrote:
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;"><br>
<br>
On Sunday, October 11, 2015 at 9:34:09 AM UTC-7, John
Coffman wrote:
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> Wayne,<br>
<br>
Some CF card adapters allow 2 CF cards to be inserted,
one on the front (IDE master) and one on the back (IDE
slave).&Acirc;&nbsp; With the adapter you are using in the photo,
is there space on the back for a slave CF card?<br>
<br>
Any IDE connector orientation allows the CF adapter to
stick up at right angles to the N8 board.&Acirc;&nbsp; With pin 1
oriented as used on the MF/PIC &amp; Mark IV boards, use
of a right-angle IDE connector allows a 2-sided adapter
to extend upward almost in the plane of the board.&Acirc;&nbsp;
(see MF/PIC in background of photo).<br>
<br>
I hope others will weigh in on this orientation issue.<br>
<br>
--John<br>
<br>
</div>
</blockquote>
<div>Hi John,</div>
<div><br>
</div>
<div>Yes, use of a 270-degree adapter would preclude the use
of a slave CF card. &Acirc;&nbsp;In my 270-degree adapter, there is
no CF card slot on the back at all. &Acirc;&nbsp;In fact, I don't
think I have ever seen a 270-degree adapter with both the
master and slave sockets.</div>
<div><br>
</div>
<div>Not sure I followed your comment about the way the
current orientation helps keep the adapter in the plane of
the host board. &Acirc;&nbsp;I took a couple photos using the Mark
IV. &Acirc;&nbsp;In one, the CF adapter is in the current, working
orientation (photo called "as-is"). &Acirc;&nbsp;In the second photo
("proposed") I have flipped the CF adapter. &Acirc;&nbsp;As far as I
can see, there is no difference in the alignment of the
space used. &Acirc;&nbsp;Only difference I note is the LEDs being on
the "back" side.</div>
<div><br>
</div>
<div>One more thing I have found that I like about the
proposed orientation is that I seem to be able to find
shrouded right-angle adapters that work. &Acirc;&nbsp;In the as-is
orientation, I cannot seem to find a suitable shrouded
right-angle adapter. &Acirc;&nbsp;As you know, I am a big fan of
shrouded connectors because they keep me from doing stupid
things...</div>
<div><br>
</div>
<div>Anyway, all this is not a big deal. &Acirc;&nbsp;I don't feel
strongly about this.</div>
<div><br>
</div>
<div>Thanks,</div>
<div><br>
</div>
<div>Wayne</div>
</blockquote>
</div>
</div>
</blockquote>
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[Wayne Warthen]

Yes, makes sense. Probably time to drop this proposal, but one last
comment is that the "top" of the CF-IDE adapters varies. In other words,
the LEDs are sometimes on the keyed side of the IDE connector and sometimes
on the non-keyed side. Below is a link to an example where the LEDs are on
the keyed side which is opposite of what you have. It seems to be the case
that the single-slot adapters usually put the LEDs on the keyed side of the
IDE connector and the dual-slot adapters usually put the LEDs on the
non-keyed side of the IDE connector. So, I guess it continues to make
sense to leave the orientation of the IDE connector as-is if the priority
is using a dual-slot adapter and keeping the LEDs facing the same way as
the components of the host board.

Thanks, Wayne


http://www.amazon.com/Syba-SD-CF-IDE-DI-Connects-3-5-Inch-Interface/dp/B000YUMLPI/ref=sr_1_3?ie=UTF8&qid=1444675547&sr=8-3&keywords=cf-ide+adapter

Wayne,
I recall going through the "orientation" argument with myself back when
the MF/PIC board was laid out. The only right angle shrouded headers I
could find orient the CF adapter with the CF cards and indicator LEDs
facing backward. I thought this orientation to be very unnatural.
I don't particularly like the bare (unshrouded) right angle headers, but
forward facing orientation won out.
If a straight-thru header is used, shrouded or not, then the indicator
LEDs and CF card face toward the center of the board.
--John

[John Coffman]

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Wayne,<br>
<br>
In the link below, pin 1 is on the left -- and the orientation key
is on the front.&nbsp; I have never seen this orientation until you
provided the link below.<br>
<br>
The cards I have ordered from eBay for $1-2 are keyed on the back,
and pin 1 of the IDE is on the right.&nbsp; Here is one such card on
Amazon:<br>
<br>
<a
href="http://www.amazon.com/Compact-Flash-Dual-Female-Converter/dp/B01325TZNC/ref=sr_1_15?ie=UTF8&amp;qid=1444681545&amp;sr=8-15&amp;keywords=cf-ide+adapter">http://www.amazon.com/Compact-Flash-Dual-Female-Converter/dp/B01325TZNC/ref=sr_1_15?ie=UTF8&amp;qid=1444681545&amp;sr=8-15&amp;keywords=cf-ide+adapter</a><br>
<br>
--John<br>
<br>
<br>
<br>
<br>
On 10/12/2015 11:54 AM, Wayne Warthen wrote:
<blockquote
cite="mid:7da14dd1-7752-46de-88fb-***@googlegroups.com"
type="cite">
<div dir="ltr">Yes, makes sense. &Acirc;&nbsp;Probably time to drop this
proposal, but one last comment is that the "top" of the CF-IDE
adapters varies. &Acirc;&nbsp;In other words, the LEDs are sometimes on the
keyed side of the IDE connector and sometimes on the non-keyed
side. &Acirc;&nbsp;Below is a link to an example where the LEDs are on the
keyed side which is opposite of what you have. &Acirc;&nbsp;It seems to be
the case that the single-slot adapters usually put the LEDs on
the keyed side of the IDE connector and the dual-slot adapters
usually put the LEDs on the non-keyed side of the IDE connector.
&Acirc;&nbsp;So, I guess it continues to make sense to leave the
orientation of the IDE connector as-is if the priority is using
a dual-slot adapter and keeping the LEDs facing the same way as
the components of the host board.
<div><br>
</div>
<div>Thanks, Wayne<br>
<div>
<div><br>
</div>
<div><br>
</div>
<div><a class="moz-txt-link-freetext" href="http://www.amazon.com/Syba-SD-CF-IDE-DI-Connects-3-5-Inch-Interface/dp/B000YUMLPI/ref=sr_1_3?ie=UTF8&amp;qid=1444675547&amp;sr=8-3&amp;keywords=cf-ide+adapter">http://www.amazon.com/Syba-SD-CF-IDE-DI-Connects-3-5-Inch-Interface/dp/B000YUMLPI/ref=sr_1_3?ie=UTF8&amp;qid=1444675547&amp;sr=8-3&amp;keywords=cf-ide+adapter</a></div>
<div><br>
</div>
<div><br>
<br>
On Sunday, October 11, 2015 at 11:38:59 PM UTC-7, John
Coffman wrote:
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> Wayne,<br>
<br>
I recall going through the "orientation" argument with
myself back when the MF/PIC board was laid out.&Acirc;&nbsp; The
only right angle shrouded headers I could find orient
the CF adapter with the CF cards and indicator LEDs
facing backward.&Acirc;&nbsp; I thought this orientation to be
very unnatural.<br>
<br>
I don't particularly like the bare (unshrouded) right
angle headers, but forward facing orientation won out.<br>
<br>
If a straight-thru&Acirc;&nbsp; header is used, shrouded or not,
then the indicator LEDs and CF card face toward the
center of the board.<br>
<br>
--John<br>
<br>
</div>
</blockquote>
</div>
</div>
</div>
</div>
</blockquote>
<br>
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[Wayne Warthen]

Yup, I think I am saying the same thing as you. The link you provided is
for a dual-slot adapter and has LEDs on the same side as the IDE connector
notch. My link is to a single-slot adapter and has the LEDs on the
opposite side from the IDE connector notch. Makes no sense to me. Was
just pointing out the existence of some inconsistencies with these
adapters... Nothing you can do about it.

Thanks,

Wayne

Wayne,
In the link below, pin 1 is on the left -- and the orientation key is on
the front. I have never seen this orientation until you provided the link
below.
The cards I have ordered from eBay for $1-2 are keyed on the back, and pin
http://www.amazon.com/Compact-Flash-Dual-Female-Converter/dp/B01325TZNC/ref=sr_1_15?ie=UTF8&qid=1444681545&sr=8-15&keywords=cf-ide+adapter
--John
Yes, makes sense. Â Probably time to drop this proposal, but one last
comment is that the "top" of the CF-IDE adapters varies. Â In other words,
the LEDs are sometimes on the keyed side of the IDE connector and sometimes
on the non-keyed side. Â Below is a link to an example where the LEDs are
on the keyed side which is opposite of what you have. Â It seems to be the
case that the single-slot adapters usually put the LEDs on the keyed side
of the IDE connector and the dual-slot adapters usually put the LEDs on the
non-keyed side of the IDE connector. Â So, I guess it continues to make
sense to leave the orientation of the IDE connector as-is if the priority
is using a dual-slot adapter and keeping the LEDs facing the same way as
the components of the host board.
Thanks, Wayne
http://www.amazon.com/Syba-SD-CF-IDE-DI-Connects-3-5-Inch-Interface/dp/B000YUMLPI/ref=sr_1_3?ie=UTF8&qid=1444675547&sr=8-3&keywords=cf-ide+adapter

Wayne,
I recall going through the "orientation" argument with myself back when
the MF/PIC board was laid out. The only right angle shrouded headers I
could find orient the CF adapter with the CF cards and indicator LEDs
facing backward. I thought this orientation to be very unnatural.
I don't particularly like the bare (unshrouded) right angle headers, but
forward facing orientation won out.
If a straight-thru header is used, shrouded or not, then the indicator
LEDs and CF card face toward the center of the board.
--John

[John Coffman]

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Wayne,<br>
<br>
It may be a kludge, but you can always solder the shrouded header
connector to the back of the board, assuming the MF/PIC orientation
with pin 1 to the right.&nbsp; (Board in portrait orientation, 96-pin ECB
connector to the bottom)<br>
<br>
--John<br>
<br>
<br>
<br>
On 10/12/2015 01:38 PM, Wayne Warthen wrote:
<blockquote
cite="mid:1834c54a-4f5b-4617-9288-***@googlegroups.com"
type="cite">
<div dir="ltr">Yup, I think I am saying the same thing as you.
&Acirc;&nbsp;The link you provided is for a dual-slot adapter and has LEDs
on the same side as the IDE connector notch. &Acirc;&nbsp;My link is to a
single-slot adapter and has the LEDs on the opposite side from
the IDE connector notch. &Acirc;&nbsp;Makes no sense to me. &Acirc;&nbsp;Was just
pointing out the existence of some inconsistencies with these
adapters... &Acirc;&nbsp;Nothing you can do about it.
<div><br>
</div>
<div>Thanks,</div>
<div><br>
</div>
<div>Wayne<br>
<br>
On Monday, October 12, 2015 at 1:27:32 PM UTC-7, John Coffman
wrote:
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> Wayne,<br>
<br>
In the link below, pin 1 is on the left -- and the
orientation key is on the front.&Acirc;&nbsp; I have never seen this
orientation until you provided the link below.<br>
<br>
The cards I have ordered from eBay for $1-2 are keyed on
the back, and pin 1 of the IDE is on the right.&Acirc;&nbsp; Here is
one such card on Amazon:<br>
<br>
<a moz-do-not-send="true"
href="http://www.amazon.com/Compact-Flash-Dual-Female-Converter/dp/B01325TZNC/ref=sr_1_15?ie=UTF8&amp;qid=1444681545&amp;sr=8-15&amp;keywords=cf-ide+adapter"
target="_blank" rel="nofollow">http://www.amazon.com/Compact-<wbr>Flash-Dual-Female-Converter/<wbr>dp/B01325TZNC/ref=sr_1_15?ie=<wbr>UTF8&amp;qid=1444681545&amp;sr=8-15&amp;<wbr>keywords=cf-ide+adapter</a><br>
<br>
--John<br>
<br>
<br>
<br>
<br>
On 10/12/2015 11:54 AM, Wayne Warthen wrote:
<blockquote type="cite">
<div dir="ltr">Yes, makes sense. &Atilde;&#8218;&Acirc;&nbsp;Probably time to
drop this proposal, but one last comment is that the
"top" of the CF-IDE adapters varies. &Atilde;&#8218;&Acirc;&nbsp;In other
words, the LEDs are sometimes on the keyed side of the
IDE connector and sometimes on the non-keyed side.
&Atilde;&#8218;&Acirc;&nbsp;Below is a link to an example where the LEDs are
on the keyed side which is opposite of what you have.
&Atilde;&#8218;&Acirc;&nbsp;It seems to be the case that the single-slot
adapters usually put the LEDs on the keyed side of the
IDE connector and the dual-slot adapters usually put
the LEDs on the non-keyed side of the IDE connector.
&Atilde;&#8218;&Acirc;&nbsp;So, I guess it continues to make sense to leave
the orientation of the IDE connector as-is if the
priority is using a dual-slot adapter and keeping the
LEDs facing the same way as the components of the host
board.
<div><br>
</div>
<div>Thanks, Wayne<br>
<div>
<div><br>
</div>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="http://www.amazon.com/Syba-SD-CF-IDE-DI-Connects-3-5-Inch-Interface/dp/B000YUMLPI/ref=sr_1_3?ie=UTF8&amp;qid=1444675547&amp;sr=8-3&amp;keywords=cf-ide+adapter"
target="_blank" rel="nofollow">http://www.amazon.com/Syba-SD-<wbr>CF-IDE-DI-Connects-3-5-Inch-<wbr>Interface/dp/B000YUMLPI/ref=<wbr>sr_1_3?ie=UTF8&amp;qid=1444675547&amp;<wbr>sr=8-3&amp;keywords=cf-ide+adapter</a></div>
<div><br>
</div>
<div><br>
<br>
On Sunday, October 11, 2015 at 11:38:59 PM
UTC-7, John Coffman wrote:
<blockquote class="gmail_quote" style="margin:
0pt 0pt 0pt 0.8ex; border-left: 1px solid
rgb(204, 204, 204); padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> Wayne,<br>
<br>
I recall going through the "orientation"
argument with myself back when the MF/PIC
board was laid out.&Atilde;&#8218;&Acirc;&nbsp; The only right angle
shrouded headers I could find orient the CF
adapter with the CF cards and indicator LEDs
facing backward.&Atilde;&#8218;&Acirc;&nbsp; I thought this
orientation to be very unnatural.<br>
<br>
I don't particularly like the bare
(unshrouded) right angle headers, but
forward facing orientation won out.<br>
<br>
If a straight-thru&Atilde;&#8218;&Acirc;&nbsp; header is used,
shrouded or not, then the indicator LEDs and
CF card face toward the center of the board.<br>
<br>
--John<br>
<br>
</div>
</blockquote>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</div>
</blockquote>
</div>
</div>
</blockquote>
<br>
</body>
</html>

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[John Coffman]

Post by Wayne Warthen
Hi John,
I would love to build this impressive SBC! A dedicated IDE-interface
would also be nice.
So far I've built the SBC-V2, the PropIO, the ColorVDU, the DiskIO V3
and the Backplane.

Jonas,

With such a monitor, the output from this board is very impressive,
especially with the SBC-188. However, too many people had too much
trouble finding a monitor that would sync to the EGA signal.

For my information, were you able to solve the EGA output problem with
the ColorVDU? I mean, were you able to find an EGA-compatible monitor?

--John

[Andrew Bingham]

John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I try
and install it in my Siemens 505 chassis / 12 slot backplane combo. If we
could "mind the edges" better on a new board, that might be beneficial.

As far as the Color VDU, I have my poor ColorVDU sitting here on my desk
useles for lack of a monitor that works with it. Because of the timing
chosen, off-the-shelf arcade adapters that *do work* with a C128 and a
simple XOR gate to create combined sync, won't work with the ColorVDU board.

I still have in my head a schematic for a monochrome, memory-mapped-page
version of the PropIO board that mimic a RAM chip using the PropIO pins and
use the shared hub RAM as basically a dual-port RAM, and would allow us to
support DOS Mode 7h (MDA-compatible mode) on the SBC-188, but I haven't had
time to prototype it out. I think this would be a great help in running
text-based DOS programs and utilities on the SBC-188. As far as I can tell
all of the resources needed to make this happen are on the Propeller.

Andrew

Post by Wayne Warthen
Hi John,
I would love to build this impressive SBC! A dedicated IDE-interface would
also be nice.
So far I've built the SBC-V2, the PropIO, the ColorVDU, the DiskIO V3 and
the Backplane.

Post by John Coffman
Jonas,

With such a monitor, the output from this board is very impressive,
especially with the SBC-188. However, too many people had too much trouble
finding a monitor that would sync to the EGA signal.
For my information, were you able to solve the EGA output problem with the
ColorVDU? I mean, were you able to find an EGA-compatible monitor?
--John

[Dan Werner]

I use a c128 monitor with my color VDU but I use the standard timing values
from the C128 ROM. The original test software that I uploaded has those
values.
Dan werner

Post by Andrew Bingham
John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I try
and install it in my Siemens 505 chassis / 12 slot backplane combo. If we
could "mind the edges" better on a new board, that might be beneficial.
As far as the Color VDU, I have my poor ColorVDU sitting here on my desk
useles for lack of a monitor that works with it. Because of the timing
chosen, off-the-shelf arcade adapters that *do work* with a C128 and a
simple XOR gate to create combined sync, won't work with the ColorVDU board.
I still have in my head a schematic for a monochrome, memory-mapped-page
version of the PropIO board that mimic a RAM chip using the PropIO pins and
use the shared hub RAM as basically a dual-port RAM, and would allow us to
support DOS Mode 7h (MDA-compatible mode) on the SBC-188, but I haven't had
time to prototype it out. I think this would be a great help in running
text-based DOS programs and utilities on the SBC-188. As far as I can tell
all of the resources needed to make this happen are on the Propeller.
Andrew

Post by Wayne Warthen
Hi John,
I would love to build this impressive SBC! A dedicated IDE-interface
would also be nice.
So far I've built the SBC-V2, the PropIO, the ColorVDU, the DiskIO V3 and
the Backplane.

Post by John Coffman
Jonas,

With such a monitor, the output from this board is very impressive,
especially with the SBC-188. However, too many people had too much trouble
finding a monitor that would sync to the EGA signal.
For my information, were you able to solve the EGA output problem with
the ColorVDU? I mean, were you able to find an EGA-compatible monitor?
--John
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[J. Alexander Jacocks]

If a C128 monitor works, then any of the several C128-to-VGA adapter boards
could convert the digital RGBI signal to one suitable for any of the
standard arcade VGA converters. I have made (but don't currently sell) a
board that does just that, in combination with a GBS-8220 converter.

http://he-insanity.blogspot.com/

I believe that another version of the same design is still for sale, from
this site:

http://bit-c128.com/

I'd be curious if anyone gives this a shot. I have the adapter, but not a
complete ECB system to test with.

- Alex

Post by Dan Werner
I use a c128 monitor with my color VDU but I use the standard timing
values from the C128 ROM. The original test software that I uploaded has
those values.
Dan werner

Post by Andrew Bingham
John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I try
and install it in my Siemens 505 chassis / 12 slot backplane combo. If we
could "mind the edges" better on a new board, that might be beneficial.
As far as the Color VDU, I have my poor ColorVDU sitting here on my desk
useles for lack of a monitor that works with it. Because of the timing
chosen, off-the-shelf arcade adapters that *do work* with a C128 and a
simple XOR gate to create combined sync, won't work with the ColorVDU board.
I still have in my head a schematic for a monochrome, memory-mapped-page
version of the PropIO board that mimic a RAM chip using the PropIO pins and
use the shared hub RAM as basically a dual-port RAM, and would allow us to
support DOS Mode 7h (MDA-compatible mode) on the SBC-188, but I haven't had
time to prototype it out. I think this would be a great help in running
text-based DOS programs and utilities on the SBC-188. As far as I can tell
all of the resources needed to make this happen are on the Propeller.
Andrew

Post by Wayne Warthen
Hi John,
I would love to build this impressive SBC! A dedicated IDE-interface
would also be nice.
So far I've built the SBC-V2, the PropIO, the ColorVDU, the DiskIO V3
and the Backplane.

Post by John Coffman
Jonas,

With such a monitor, the output from this board is very impressive,
especially with the SBC-188. However, too many people had too much trouble
finding a monitor that would sync to the EGA signal.
For my information, were you able to solve the EGA output problem with
the ColorVDU? I mean, were you able to find an EGA-compatible monitor?
--John
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[Andrew Bingham]

The Color VDU already does the "resistor network DAC" and the "brown fix"
to generate analog voltages on the output pins on the VGA connector
onboard, so that is not needed. The issue is sync. I've tried both
seperate sync and combined sync (using an XOR gate to generate the sync
signal, as mentioned on
https://sites.google.com/site/h2obsession/CBM/C128/rgbi-to-vga) and this
does not work. The SBC-188 test program for the ColorVDU combined with the
16.257Mhz pixel clock sets a horizontal sync timing of ~18khz and a vsync
of ~48hz. The GBS-8220 wants 15khz or 30khz, as far as I can tell, 18hz is
outside the range where it will sync.

Andrew

Post by J. Alexander Jacocks
If a C128 monitor works, then any of the several C128-to-VGA adapter
boards could convert the digital RGBI signal to one suitable for any of the
standard arcade VGA converters. I have made (but don't currently sell) a
board that does just that, in combination with a GBS-8220 converter.
http://he-insanity.blogspot.com/
I believe that another version of the same design is still for sale, from
http://bit-c128.com/
I'd be curious if anyone gives this a shot. I have the adapter, but not a
complete ECB system to test with.
- Alex

Post by Dan Werner
I use a c128 monitor with my color VDU but I use the standard timing
values from the C128 ROM. The original test software that I uploaded has
those values.
Dan werner

Post by Andrew Bingham
John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I try
and install it in my Siemens 505 chassis / 12 slot backplane combo. If we
could "mind the edges" better on a new board, that might be beneficial.
As far as the Color VDU, I have my poor ColorVDU sitting here on my desk
useles for lack of a monitor that works with it. Because of the timing
chosen, off-the-shelf arcade adapters that *do work* with a C128 and a
simple XOR gate to create combined sync, won't work with the ColorVDU board.
I still have in my head a schematic for a monochrome, memory-mapped-page
version of the PropIO board that mimic a RAM chip using the PropIO pins and
use the shared hub RAM as basically a dual-port RAM, and would allow us to
support DOS Mode 7h (MDA-compatible mode) on the SBC-188, but I haven't had
time to prototype it out. I think this would be a great help in running
text-based DOS programs and utilities on the SBC-188. As far as I can tell
all of the resources needed to make this happen are on the Propeller.
Andrew

Post by Wayne Warthen
Hi John,
I would love to build this impressive SBC! A dedicated IDE-interface
would also be nice.
So far I've built the SBC-V2, the PropIO, the ColorVDU, the DiskIO V3
and the Backplane.

Post by John Coffman
Jonas,

With such a monitor, the output from this board is very impressive,
especially with the SBC-188. However, too many people had too much trouble
finding a monitor that would sync to the EGA signal.
For my information, were you able to solve the EGA output problem with
the ColorVDU? I mean, were you able to find an EGA-compatible monitor?
--John
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[John Coffman]

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On 10/11/2015 09:27 AM, Andrew Bingham wrote:
<blockquote
cite="mid:2e3b4255-744c-4490-bdc7-***@googlegroups.com"
type="cite"> &Acirc;&nbsp;The SBC-188 test program for the ColorVDU combined
with the 16.257Mhz pixel clock sets a horizontal sync timing of
~18khz and a vsync of ~48hz. &Acirc;&nbsp;The GBS-8220 wants 15khz or 30khz,
as far as I can tell, 18hz is outside the range where it will
sync. &Acirc;&nbsp;</blockquote>
<br>
The ColorVDU support for the SBC-188 uses exact EGA timing:&nbsp;
H:18.4Khz V:48hz.&nbsp; Other refresh rates can be achieved with
different CRTC values, notably NTSC or PAL timing for use with a
converter to a TV composite video signal.&nbsp; However, some app-note I
saw mentioned that the 8563 has trouble generating an interlaced
signal.&nbsp; I have not tried generating an NTSC signal.<br>
<br>
--John<br>
<br>
<br>
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[J. Alexander Jacocks]

If the ColorVDU does EGA timing, then the GBS-8220 _will_ work, as it is
designed as an EGA/CGA/arcade to VGA adapter.

Again, I'd love to help test, and I do have a complete GBS-8220, but my
Mark IV ECB CPU board is not yet working, and I don't have the time (3
month old daughter) to fix the CPU board.

- Alex

 The SBC-188 test program for the ColorVDU combined with the 16.257Mhz
pixel clock sets a horizontal sync timing of ~18khz and a vsync of ~48hz.
 The GBS-8220 wants 15khz or 30khz, as far as I can tell, 18hz is outside
the range where it will sync. Â
The ColorVDU support for the SBC-188 uses exact EGA timing: H:18.4Khz
V:48hz. Other refresh rates can be achieved with different CRTC values,
notably NTSC or PAL timing for use with a converter to a TV composite video
signal. However, some app-note I saw mentioned that the 8563 has trouble
generating an interlaced signal. I have not tried generating an NTSC
signal.
--John
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[Andrew Bingham]

Here's the relevant section of the GBS-8220 manual:

<Loading Image...>


The 18.4 khz horizontal sync doesn't fall within any of the ranges defined
for sync for the -8220 boards. I'd love to be proven wrong, but I've tried
it, with an XOR gate to create combined sync (per
https://sites.google.com/site/h2obsession/CBM/C128/rgbi-to-vga which works
with a C128), checked the sync signal with an logic analyzer, no dice.


Andrew

Post by J. Alexander Jacocks
If the ColorVDU does EGA timing, then the GBS-8220 _will_ work, as it is
designed as an EGA/CGA/arcade to VGA adapter.
Again, I'd love to help test, and I do have a complete GBS-8220, but my
Mark IV ECB CPU board is not yet working, and I don't have the time (3
month old daughter) to fix the CPU board.
- Alex

 The SBC-188 test program for the ColorVDU combined with the 16.257Mhz
pixel clock sets a horizontal sync timing of ~18khz and a vsync of ~48hz.
 The GBS-8220 wants 15khz or 30khz, as far as I can tell, 18hz is outside
the range where it will sync. Â
The ColorVDU support for the SBC-188 uses exact EGA timing: H:18.4Khz
V:48hz. Other refresh rates can be achieved with different CRTC values,
notably NTSC or PAL timing for use with a converter to a TV composite video
signal. However, some app-note I saw mentioned that the 8563 has trouble
generating an interlaced signal. I have not tried generating an NTSC
signal.
--John
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[Richard Cini]

I have one of those and never got it to work consistently with a VGA monitor. I wound up buying off of eBay the same Vizio TV that John uses.

I know there is a separate thread on the CVDU that I haven't read yet, but personally I'd love to see a true 8-bit VGA adapter on the ECB, even if it's a stacked board. Not sure if there's enough board real estate for it, but that's my dream :-)


Sent from my iPhone

If the ColorVDU does EGA timing, then the GBS-8220 _will_ work, as it is designed as an EGA/CGA/arcade to VGA adapter.
Again, I'd love to help test, and I do have a complete GBS-8220, but my Mark IV ECB CPU board is not yet working, and I don't have the time (3 month old daughter) to fix the CPU board.
- Alex

 The SBC-188 test program for the ColorVDU combined with the 16.257Mhz pixel clock sets a horizontal sync timing of ~18khz and a vsync of ~48hz.  The GBS-8220 wants 15khz or 30khz, as far as I can tell, 18hz is outside the range where it will sync. Â

The ColorVDU support for the SBC-188 uses exact EGA timing: H:18.4Khz V:48hz. Other refresh rates can be achieved with different CRTC values, notably NTSC or PAL timing for use with a converter to a TV composite video signal. However, some app-note I saw mentioned that the 8563 has trouble generating an interlaced signal. I have not tried generating an NTSC signal.
--John
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[John Coffman]

Post by Andrew Bingham
John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I
try and install it in my Siemens 505 chassis / 12 slot backplane
combo. Â If we could "mind the edges" better on a new board, that
might be beneficial. Â

Early N8 boards left little or no clearance at the edges. At Wolfgang's
urging, space was left at the edges for card-slot insertion on all
boards starting 3-4 years ago. Unfortunately, the SBC-188 was not one
of the boards where this was possible when we went to rev. 2 because an
additional 14-pin chip had to be added to an already very dense board.

There is only one way to gain the extra space needed for the
card-insertion allowance: eliminate some components. This can be done by:
1. Using a GAL or two. Bad, because not everyone can program GAL's.
2. Convert the UART to PLCC. There are 2 pluses here. A little
space is gained, and the PLCC version (-550C) correctly supports RTS/CTS
protocol in hardware.
3. Go to an IDE-8 direct interface and eliminate the 8255. This
gains a lot of space, and unless I hear lots of screams about not having
the PIO chip, is looking like a very good option.

Thank you, Andrew, for raising this issue. It needs to be addressed.

--John

[Ian May]

Hi John,
I'm not particularly interested in keeping the 8255 (dedicated hardware
must be faster), but if you are considering changing to a PLCC UART to save
space why not change to a PLCC 8255? e.g.
http://avnetexpress.avnet.com/1/1/817291-intersil-cmos-programmable-peripheral-interface-44-pin-plcc-cms82c55az.html
at US$3.828 ea 3000+ in stock. The data sheet says "No Bus Hold Devices on
any Port Pins" which a (more expensive) CS82C55A does have.
http://www.mouser.com/ProductDetail/Intersil/CS82C55A/?Intersil%2fCS82C55A%2f&qs=B4b5rvZIvWUnccxLBJ0S4g==
US$11.60 ea 515 in stock. The data sheet does not say what the consequences
of "No Bus Hold Devices" are and what happens may also depend on the
software. So it may not be a direct replacement for a regular 8255.
Cheers, Ian.

Post by John Coffman

Post by Andrew Bingham
John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I
try and install it in my Siemens 505 chassis / 12 slot backplane
combo. Â If we could "mind the edges" better on a new board, that
might be beneficial. Â

Early N8 boards left little or no clearance at the edges. At Wolfgang's
urging, space was left at the edges for card-slot insertion on all
boards starting 3-4 years ago. Unfortunately, the SBC-188 was not one
of the boards where this was possible when we went to rev. 2 because an
additional 14-pin chip had to be added to an already very dense board.
There is only one way to gain the extra space needed for the
1. Using a GAL or two. Bad, because not everyone can program GAL's.
2. Convert the UART to PLCC. There are 2 pluses here. A little
space is gained, and the PLCC version (-550C) correctly supports RTS/CTS
protocol in hardware.
3. Go to an IDE-8 direct interface and eliminate the 8255. This
gains a lot of space, and unless I hear lots of screams about not having
the PIO chip, is looking like a very good option.
Thank you, Andrew, for raising this issue. It needs to be addressed.
--John
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[John Coffman]

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Ian,<br>
<br>
My original list had 8255--&gt;PLCC? on it.&nbsp; But that was before the
suggestion to go to a direct IDE8 interface came up.&nbsp; My leaning at
this time is to go the IDE8 route, ala MarkIV, and eliminate the
8255.<br>
<br>
The main argument to eliminate the 8255 is to ease board
overcrowding.&nbsp; I have not heard yet of any objections to this major
change.<br>
<br>
--John<br>
<br>
<br>
<br>
On 10/11/2015 11:50 PM, Ian May wrote:
<blockquote
cite="mid:***@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>Hi John,<br>
I'm not particularly interested in keeping the 8255 (dedicated
hardware must be faster), but if you are considering changing
to a PLCC UART to save space why not change to a PLCC 8255?
e.g. <a moz-do-not-send="true"
href="http://avnetexpress.avnet.com/1/1/817291-intersil-cmos-programmable-peripheral-interface-44-pin-plcc-cms82c55az.html"
target="_blank">http://avnetexpress.avnet.com/1/1/817291-intersil-cmos-programmable-peripheral-interface-44-pin-plcc-cms82c55az.html</a>
at US$3.828 ea 3000+ in stock. The data sheet says "No Bus
Hold Devices on any Port Pins" which a (more expensive)
CS82C55A does have. <a moz-do-not-send="true"
href="http://www.mouser.com/ProductDetail/Intersil/CS82C55A/?Intersil%2fCS82C55A%2f&amp;qs=B4b5rvZIvWUnccxLBJ0S4g=="
target="_blank">http://www.mouser.com/ProductDetail/Intersil/CS82C55A/?Intersil%2fCS82C55A%2f&amp;qs=B4b5rvZIvWUnccxLBJ0S4g==</a>&Acirc;&nbsp;
US$11.60 ea 515 in stock. The data sheet does not say what the
consequences of "No Bus Hold Devices" are and what happens may
also depend on the software. So it may not be a direct
replacement for a regular 8255.<br>
</div>
Cheers, Ian.<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Oct 12, 2015 at 2:17 AM, John
Coffman <span dir="ltr">&lt;<a moz-do-not-send="true"
href="mailto:***@gmail.com" target="_blank">***@gmail.com</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;"><span class="">On 10/10/2015 08:25 PM,
Andrew Bingham wrote:<br>
&gt; John - one of the oscillators on the right hand side
of the SBC-188<br>
&gt; overhangs and creates an interference with the card
close edges when I<br>
&gt; try and install it in my Siemens 505 chassis / 12
slot backplane<br> </span>&gt; combo. &Atilde;&#8218; If we could "mind the edges" better on
a new board, that<br>
&gt; might be beneficial. &Atilde;&#8218;<br>
&gt;<br>
<br>
Early N8 boards left little or no clearance at the edges.&Acirc;&nbsp;
At Wolfgang's<br>
urging, space was left at the edges for card-slot insertion
on all<br>
boards starting 3-4 years ago.&Acirc;&nbsp; Unfortunately, the SBC-188
was not one<br>
of the boards where this was possible when we went to rev. 2
because an<br>
additional 14-pin chip had to be added to an already very
dense board.<br>
<br>
There is only one way to gain the extra space needed for the<br>
card-insertion allowance:&Acirc;&nbsp; eliminate some components.&Acirc;&nbsp;
This can be done by:<br>
&Acirc;&nbsp; &Acirc;&nbsp; 1.&Acirc;&nbsp; Using a GAL or two.&Acirc;&nbsp; Bad, because not everyone
can program GAL's.<br>
&Acirc;&nbsp; &Acirc;&nbsp; 2.&Acirc;&nbsp; Convert the UART to PLCC.&Acirc;&nbsp; There are 2 pluses
here.&Acirc;&nbsp; A little<br>
space is gained, and the PLCC version (-550C) correctly
supports RTS/CTS<br>
protocol in hardware.<br>
&Acirc;&nbsp; &Acirc;&nbsp; 3.&Acirc;&nbsp; Go to an IDE-8 direct interface and eliminate the
8255.&Acirc;&nbsp; This<br>
gains a lot of space, and unless I hear lots of screams
about not having<br>
the PIO chip, is looking like a very good option.<br>
<br>
Thank you, Andrew, for raising this issue.&Acirc;&nbsp; It needs to be
addressed.<br>
<div class="HOEnZb">
<div class="h5"><br>
--John<br>
<br>
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[Ian May]

Hi John,
I hadn't looked at the Mark IV schematic. Now I see that you gain all the
space of the 8255 where before I thought you would be fitting something
like the interface on the Dual IDE card instead of the 8255.
Cheers, Ian.

Ian,
My original list had 8255-->PLCC? on it. But that was before the
suggestion to go to a direct IDE8 interface came up. My leaning at this
time is to go the IDE8 route, ala MarkIV, and eliminate the 8255.
The main argument to eliminate the 8255 is to ease board overcrowding. I
have not heard yet of any objections to this major change.

[Richard Cini]

If you ditch the 8255, then you lose a parallel port for possible use for a printer. If the Centronics board or ModPrn are available then it would be fine. Not sure how many would use it for printing anyway.

Sent from my iPhone

Ian,
My original list had 8255-->PLCC? on it. But that was before the suggestion to go to a direct IDE8 interface came up. My leaning at this time is to go the IDE8 route, ala MarkIV, and eliminate the 8255.
The main argument to eliminate the 8255 is to ease board overcrowding. I have not heard yet of any objections to this major change.
--John

Post by Wayne Warthen
Hi John,
I'm not particularly interested in keeping the 8255 (dedicated hardware must be faster), but if you are considering changing to a PLCC UART to save space why not change to a PLCC 8255? e.g. http://avnetexpress.avnet.com/1/1/817291-intersil-cmos-programmable-peripheral-interface-44-pin-plcc-cms82c55az.html at US$3.828 ea 3000+ in stock. The data sheet says "No Bus Hold Devices on any Port Pins" which a (more expensive) CS82C55A does have. http://www.mouser.com/ProductDetail/Intersil/CS82C55A/?Intersil%2fCS82C55A%2f&qs=B4b5rvZIvWUnccxLBJ0S4g==Â Ian,
My original list had 8255-->PLCC? on it. But that was before the suggestion to go to a direct IDE8 interface came up. My leaning at this time is to go the IDE8 route, ala MarkIV, and eliminate the 8255.
The main argument to eliminate the 8255 is to ease board overcrowding. I have not heard yet of any objections to this major change.
--John

Post by Wayne Warthen
Hi John,
I'm not particularly interested in keeping the 8255 (dedicated hardware must be faster), but if you are considering changing to a PLCC UART to save space why not change to a PLCC 8255? e.g. http://avnetexpress.avnet.com/1/1/817291-intersil-cmos-programmable-peripheral-interface-44-pin-plcc-cms82c55az.html at US$3.828 ea 3000+ in stock. The data sheet says "No Bus Hold Devices on any Port Pins" which a (more expensive) CS82C55A does have. http://www.mouser.com/ProductDetail/Intersil/CS82C55A/?Intersil%2fCS82C55A%2f&qs=B4b5rvZIvWUnccxLBJ0S4g==Â US$11.60 ea 515 in stock. The data sheet does not say what the consequences of "No Bus Hold Devices" are and what happens may also depend on the software. So it may not be a direct replacement for a regular 8255.
Cheers, Ian.

Post by Andrew Bingham
John - one of the oscillators on the right hand side of the SBC-188
overhangs and creates an interference with the card close edges when I
try and install it in my Siemens 505 chassis / 12 slot backplane
combo. Â If we could "mind the edges" better on a new board, that
might be beneficial. Â

Early N8 boards left little or no clearance at the edges. At Wolfgang's
urging, space was left at the edges for card-slot insertion on all
boards starting 3-4 years ago. Unfortunately, the SBC-188 was not one
of the boards where this was possible when we went to rev. 2 because an
additional 14-pin chip had to be added to an already very dense board.
There is only one way to gain the extra space needed for the
  1. Using a GAL or two. Bad, because not everyone can program GAL's.
  2. Convert the UART to PLCC. There are 2 pluses here. A little
space is gained, and the PLCC version (-550C) correctly supports RTS/CTS
protocol in hardware.
  3. Go to an IDE-8 direct interface and eliminate the 8255. This
gains a lot of space, and unless I hear lots of screams about not having
the PIO chip, is looking like a very good option.
Thank you, Andrew, for raising this issue. It needs to be addressed.
--John
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