Help: Commodore 1901 monitor pinouts?
Christian von Krogh
'chroma' inputs, and a mono audio input. It also has a switch on the front
which
says 'RGB/PAL'.
Does anyone have information on the monitor, esp. the pinout of the D9-plug,
and instructions
on how to use it and the two 'chroma' inputs?
I am trying to hook the monitor up to an Amiga 500. It was supposedly sold
as a bundle (the 1901 and the A500) in the UK, so it should be possible. I
already have connected it to the monochrome output of the A500, but it is
only in b/w...
Any help is appreciated
-Christian von Krogh
c...@soon.com
John H. Guillory
wrote:
>I recently bought a second-hand 1901 monitor. It has a D9- input, two
>'chroma' inputs, and a mono audio input. It also has a switch on the front
>which
>says 'RGB/PAL'.
The RGB (9-pin) should be compatible with the C128 (and possibly amiga
from the way my monitor acts....) I have a monitor similiar to yours,
but I have a 4-way switch that has RGB Analog|RGB
Monochrome|RGBI|Composite The RGB Analog is made for the Amiga, but
works beautifully on the 128 as well. RGBI is the standard way of
doing 80-column RGB on a C128. PAL (composite) uses the 2 RCA jacks
on the back with a standard connector.
>Does anyone have information on the monitor, esp. the pinout of the D9-plug,
>and instructions
>on how to use it and the two 'chroma' inputs?
You can try project64.c64.org, but I can't say that I ever saw that
one up there... The 1702's manual is often on the various sites, but
don't think anyone ever scanned in the 1901.... Perhaps you can
request someone add it if they have the manual.... The D9 input is a
standard pin-out. According to my C128D book it is as follows:
[5 4 3 2 1]
[9 8 7 6]
1 - Ground
2 - Ground
3 - Red
4 - Green
5 - Blue
6 - Intensity
7 - Monochrome
8 - Horizontal Sync
9 - Vertical Sync
I used to have a Monochrome->RCA converters (still do, but not as easy
to break apart) that tied pin 7 to the center of a RCA connector and
I believe the Ground (may have been one of the sync's but I'm almost
positive it was the ground) to the outside of the RCA. In theory you
should be able to do the same to achieve a seperated Chroma/Luma
signal by tieing Pins 3-5 to the center of a RCA jack, and ground on
the outside, for the other signal, you'd probably use monochrome and
ground. The Connectors for seperated video signal is as follows:
Luminance = Sync. Output (Black and white I believe) (which on a C128
goes to pin1 of the 8-pin DIN, with Ground on the outside of the
RCA.... (pin2)
Audio Out is on Pin3 of the DIN, with ground from pin2...
Video Out is on Pin 4 (ground on pin2) for Composite Signal Output
(great for hooking up a 128 to a VCR (or 2-connector monitors like I
have over here....)
Audio In is Pin 5 (ground on pin 2) Which I am not 100% sure why they
put this pin on here with NO USEFULL INFORMATION ON IT. Someone
posted a way of flipping a bit at memory location 2 and reading
location 3 (1-bit) to hear the tape deck, perhaps this gives similiar
results or has a similiar way to read it, although 1-bit at a time
would require heavy duty buffering, and wouldn't be the best
recording device available....
Color Out (Chroma signal) is on pin 6 (ground on pin2) which provides
the color for the seperated signal Most connectors have pin 6 on the
inside of a RCA and pin2 on the outside for Chroma, with Luminnance
wired as above, and audio out on a 3-connector cable for 40-column
output. A 5-pin DIN is available for the C64, which has 1=luminance,
2=ground,3=audio out, 4=video out,5=audio in. Unfortiantly, I'm not
sure if the Video Out is equivilent of pin 6 or pin4.... I'm guessing
pin4, but...
>I am trying to hook the monitor up to an Amiga 500. It was supposedly sold
>as a bundle (the 1901 and the A500) in the UK, so it should be possible. I
>already have connected it to the monochrome output of the A500, but it is
>only in b/w...
Unfortiantly, I'm not too familiar with the Amiga series, and most of
the folks in comp.sys.commodore don't consider the Amiga a
commodore....That's o.k. because I really don't consider either the
Amiga or the SuperCPU a commodore. ;-) From what my monitor's manual
says, the Analog RGB allows for 4096 colors (which is what the Amiga
uses) and apparently uses the same basic configuration as the 128's
RGBI connector, with the exception that its analog (meaning that there
is many subtle differences in voltages on each of the RGB pins, where
as the 128 uses a ON and OFF stateon each of the R,G,B, and I pins to
give 16 colors. The monitor is also compatible with IBM's CGA
standard, and due to the way that the 128 has the monochrome pin used
(and my monitor has a monochrome mode) there stands a chance that the
monitor is compatible with Monochrome video cards as well...
John Iannetta
"I used to have a Monochrome->RCA converters (still do, but not as easy
to break apart) that tied pin 7 to the center of a RCA connector and
I believe the Ground (may have been one of the sync's but I'm almost
positive it was the ground) to the outside of the RCA. In theory you
should be able to do the same to achieve a seperated Chroma/Luma
signal by tieing Pins 3-5 to the center of a RCA jack, and ground on
the outside, for the other signal, you'd probably use monochrome and
ground.".
Yes, you want ground (pin 1 or 2) connected to the shell of the RCA phono
plug. But you DON'T want to tie pins 3, 4, and 5 of the C-128's RGBI coonector
together. The impedances and voltage levels of the RGBI output connector are
completely different from those of the 8-pin AUDIO/VIDEO connector. More
importantly, if the R, G, and B outputs are not all at the same level (either
high or low), you would be putting close to a short circuit between the tie
point and ground. To convert the RGBI signal to a color composite signal, a
small circuit is required.
John continued (about the AUDIO/VIDEO connector):
"Audio In is Pin 5 (ground on pin 2) Which I am not 100% sure why they
put this pin on here with NO USEFULL INFORMATION ON IT.".
You can feed that pin with an audio signal from the AUX output of an audio
amplifier, receiver, tape deck, etc.; the input impedance is approximately 150
kohm. The AC voltage should be about 500 millivolts RMS. The signal is routed
through SID register $18 (24), and also through all selected filters if bit 3
of SID register $17 (23) is set. Thus, a tremelo effect may be produced, or
a robotic sound using filtering. The external signal is combined with the SID
voices (if any are selected) to produce the audio output.
John added:
"A 5-pin DIN is available for the C64, which has 1=luminance, 2=ground,
3=audio out, 4=video out, 5=audio in. Unfortiantly, I'm not sure if the Video
Out is equivilent of pin 6 or pin4.... I'm guessing pin4, but...".
The very first production C-64 PC board used the 5-pin connector; later
boards used the 8-pin connector. Although the CHROMA signal (pin 6 of the
8-pin connector) is not outputted, it is generated by VIC. And if an 8-pin
connector is installed, the signal may be outputted by using two resistors.
And yes, pin 4 does the same job for all boards, 5-pin and 8-pin.
John concluded:
"From what my monitor's manual says, the Analog RGB allows for 4096 colors
(which is what the Amiga uses) and apparently uses the same basic configuration
as the 128's RGBI connector, with the exception that its analog (meaning that
there is many subtle differences in voltages on each of the RGB pins, whereas
as the 128 uses a ON and OFF stateon each of the R,G,B, and I pins to give 16
colors.".
Analog RGB doesn't use an I pin, so you would get eight different colors
connecting the C-128's RGBI output to the monitor's analog RGB input.
--
123 456
789 *0#
If you see a telephone keypad above, you're probably using a Commodore 64.
Christian von Krogh
> Analog RGB doesn't use an I pin, so you would get eight different
colors
> connecting the C-128's RGBI output to the monitor's analog RGB input.
I guess the conclusion will be to connect the Amiga's hor/ver sync + analog
RGB signals to the hor/ver sync + digital RGB on the monitor for a maximum
of 8 different colors.
Another solution I was given from Mr. Tore Bjoernsen in a norwegian Amiga
news group, was to get an RF modulator for the Amiga, and then feed the
video output from the modulator to both of the 'chroma' inputs on the
monitor using an Y-cable split (one of the 'chroma's is really 'luma', there
is an error in the labelling on the monitor).
Mr. Bjoernsen also mentioned a firm in the UK, called Trilogic, which
released a folder in '89 explaining a procedyre to convert the 1901 to
analog RGB:
(Quote:)
"...If you have a 1901 monitor then we can convert it to RGB analogue so
that it will give all 4096 colours with the Amiga.A converted 1901
gives an excellent picture better than the Philips 8833 or Commodore
1084/S monitors. Conversions costs £29.95 including a lead plus p&p
both ways.
We regret that we cannot supply a kit of parts - the conversion must
be done in our workshop
..."
This sounds like an interesting hobby project! Does anyone have detailed
technical info on how they did this? Or maybe know if the firm still exists
from which we could get some info? (Probably a long shot...)
-Christian
John Iannetta
"Another solution I was given from Mr. Tore Bjoernsen in a norwegian Amiga
news group, was to get an RF modulator for the Amiga, and then feed the
video output from the modulator to both of the 'chroma' inputs on the
monitor using an Y-cable split (one of the 'chroma's is really 'luma', there
is an error in the labelling on the monitor).".
An RF modulator won't do you any good; it has a video INPUT, not OUTPUT.
I am not familiar with the Amiga, but I believe that all models offered (either
internally or externally) an RF modulator, for connecting to a TV receiver.
If you connect the RF OUT of the modulator to the antenna terminals of a VCR,
and connect the VIDEO OUT of the VCR to the VIDEO IN of the 1901, you should
be able to display all of the Amiga's colors. And if the VCR has S-Video
outputs, and you connect them to the LUMA and CHROMA inputs of the monitor,
the picture should be better. The modulation/demodulation process will, of
necessity, introduce signal degradation. But you won't be limited to eight
colors.
The Motorola MC1377 is an inexpensive integrated circuit that converts
analog RGB to composite (either PAL or NTSC). Only a few external parts are
required. I'll send you the suggested Motorola circuit by E-mail if you want
it.
Christian von Krogh
OUTPUT.
I think maybe I've been a bit unclear about what I meant with RF-modulator.
According to a small leaflet for the Commodore A520 Video Adapter, this
little box indeed has a video output (in addition to an RF output).
But the circuit you mention is interesting, as I only have the leaflet, not
the box itself.
-Christian
Groepaz
> The Motorola MC1377 is an inexpensive integrated circuit that converts
> analog RGB to composite (either PAL or NTSC). Only a few external parts are
> required. I'll send you the suggested Motorola circuit by E-mail if you want
> it.
would you send me that shematic aswell? :P
gpz/hit