No after market ROM.
Logically, I would think the fact that the top four lines are perfect,
the hard reset produces a perfect Menu screen, and just the bottom
four lines are garbled would be a clue where to look.
I know nothing other than reading a lot off Internet. My instinct
tells me the issue is a component that regulates power or signals to
the LCD driver chips for the bottom half of the screen. The are
getting power (because we see gibberish and the perfect Menu screen)
but perhaps it is the wrong voltage or intermittent power or signal.
Thoughts are:
Capacitors C47 or C54 and or M17 and/or M25.
But I don't know how to determine their impact on the issue.
On Sunday, July 26, 2020, 11:25:01 AM EDT, Jeffrey Birt
<bir...@soigeneris.com> wrote:
When comparing your two pictures, after rotating them right side up, I
noticed just now that not only do you have blank blocks but some of
the characters are reversed. That is really bizarre. I’m not sure if
that points to a problem with how the LCD drivers are being
configured/initialized or what data is being sent to them.
If the driver ships are outputting a built-in font here it might be a
chip configuration issue. If the display is always bit mapped, then it
would be something else.
Do you have any sort of aftermarket ROM installed?
Very interesting problem.
Jeff Birt
*From:* M100 <m100-boun...@lists.bitchin100.com> *On Behalf Of *Chris
Fezzler
*Sent:* Sunday, July 26, 2020 9:47 AM
*To:* m...@bitchin100.com
*Subject:* Re: [M100] Listserv Search
Gladly.
On Sunday, July 26, 2020, 08:36:06 AM EDT, Jeffrey Birt
<bir...@soigeneris.com <mailto:bir...@soigeneris.com>> wrote:
Can you attach a picture of the cold boot screen too?
The positive and negative clips go to a +5 and ground source on the
M100 PCB itself. The PPS setting if ‘Pulses Per Second’ when using it
as a logic pulser, i.e. to inject a pulsing signal. On the chip select
lines you should she them quickly toggling.
Jeff Birt
*From:*M100 <m100-boun...@lists.bitchin100.com
<mailto:m100-boun...@lists.bitchin100.com>> *On Behalf Of *Chris Fezzler
*Sent:* Saturday, July 25, 2020 6:20 PM
*To:* m...@bitchin100.com <mailto:m...@bitchin100.com>
*Subject:* Re: [M100] Listserv Search
*ALERT*: Beginner asking question.
*Reminder:*Upon hard reset the LCD initializes perfectly and displays
the main Menu screen perfectly. However, once in BASIC or TEXT the
bottom four lines do not display correctly. /(See attached.)/
/(Planned to test LCD in M102 but it has a different connector. I
don't have a second M100 right now to test it in, but I am 99.99%
positive the LCD is fine)/
So I purchased a logic prob (Elenco LP-900)
<https://www.jpmsupply.com/Logic-Probe-and-Pulser-Combination-Elenco-LP-900-p/80311.htm> to
test chip select lines on the LCD connector (Pins 14, 12, 10, 8, 7,
16,15,13,11, 9, and CS1=Pin? - /schematics blurry/).
As I unboxed it I remembered I never used one before. :)
- Where do I place the/pos/ and /neg/ alligator clips?
- Do I set the logic prob to/400PPS/ or/00.5PPS/?
- In checking the chip select lines, am I looking for /HI, LO, or PULSE/?
I see no broken or corroded lines on the board.
Thanks in advance.
On Wednesday, July 22, 2020, 02:29:39 PM EDT, Jeffrey Birt
<bir...@soigeneris.com <mailto:bir...@soigeneris.com>> wrote:
This loss of an entire block is the symptom of a missing chip select.
When the LCD driver chips are powered/reset they will drive every
pixel on/black. When they receive the proper initialization, they will
drive every pixel off/clear. It seems the rest and initialization
steps are being done so commands are getting through (and the machine
is booting so the LCD has to be initializing and responding).
Each driver chip on the LCD controls one block of pixels. If an entire
block is missing, it is a good sign the chip select is not getting
through. It could be a bad trace on the M100, a bad LCD cable or a bad
LCD itself. If you have a scope of logic probe you can check to see if
all the chip select lines are toggling.
Jeff BIrt
*From:*M100 <m100-boun...@lists.bitchin100.com
<mailto:m100-boun...@lists.bitchin100.com>> *On Behalf Of *Chris Fezzler
*Sent:* Wednesday, July 22, 2020 11:26 AM
*To:* m...@bitchin100.com <mailto:m...@bitchin100.com>
*Subject:* Re: [M100] Listserv Search
Here you go.
On Wednesday, July 22, 2020, 11:52:23 AM EDT, Stephen Adolph
<twospru...@gmail.com <mailto:twospru...@gmail.com>> wrote:
a pic of the garbled screen would be great if you can do it.. thanks
On Wed, Jul 22, 2020 at 11:37 AM Chris Fezzler <fezz...@yahoo.com
<mailto:fezz...@yahoo.com>> wrote:
Sorry - typing too fast. Top four lines of the screen.
Yes, mostly garbage all of the time. Except a hard rest will
generate a proper menu screen.
Yes, in BASIC the same. But if I type in a test program and hit
RUN the program will indeed run.
So the computer is getting the commands/keystrokes. Just not
displaying bottom four lines.
I think it is a component issue.
On Wednesday, July 22, 2020, 09:20:53 AM EDT, Stephen Adolph
<twospru...@gmail.com <mailto:twospru...@gmail.com>> wrote:
Hi Chris,
What do you mean by "the top 4". Do you mean top 4 lines on the
screen? I think so.
So is it correct to say that the LCD bottom 4 lines display
garbage at certain times
* not after a (hard) reset - you get a correct MENU display (not
just a RESET but a HARD RESET?)
* when you enter BASIC and/or run any software, the LCD bottom
half shows garbage?
I would suggest that you run a memory test.
I doubt that you have a fundamental problem with the LCD system,
nor the keyboard system.
good problem!
On Wed, Jul 22, 2020 at 9:02 AM Chris Fezzler <fezz...@yahoo.com
<mailto:fezz...@yahoo.com>> wrote:
I'm trying to troubleshoot what components on the circuit
board process keystrokes and send them to the screen.
The screen and keyboard on my Model 100 are in perfect working
order. But only the top four are processing correctly.
The bottom four are displaying gibberish. But if I type
commands in BASIC, they work. So again, not the keyboard or
screen but components that process the bottom half. A hard
rest will present a perfect menu screen. But upon entering
an app, the bottom four lines are not getting proper signal.
Sorry, I'm not an electronics or computer engineer. Just a
hobbyist with a soldering iron and a willingness to learn.
Plan to look at Technical Reference Manual to see if I can
troubleshoot.
On Wednesday, July 22, 2020, 01:15:25 AM EDT, John R.
Hogerhuis <jho...@pobox.com <mailto:jho...@pobox.com>> wrote:
On Tue, Jul 21, 2020 at 5:08 PM Chris Fezzler
<fezz...@yahoo.com <mailto:fezz...@yahoo.com>> wrote:
Is there a way to search old Listserv messages so I can
research before embarrass...err...I mean ask a dumb question.
Seriously, would like to research.
How old are we talking?
Gmane was our archive until it went down for a long time. Then
it was back up recently but only accessible through nntp
readers. Not sure the status of that.
Our GNU Mailman list itself has an archive which goes back to
2011 when I took over running the list.
http://lists.bitchin100.com/private.cgi/m100-bitchin100.com/
Or just ask. We Are The Archive.
-- John.
