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IBM 5155 with monitor (commmodore) 184S or Philips CM883

andromeda92

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Hi,
I wanted to know if I could connect IBM 5155 from CGA card to the commodore 1084S monitor or Philips CM8833, they are RGB (CGA) monitors, with the cable that is fine.

Thanks for your help.
 

s3freak

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Signal wise, as long as the monitors can take a 15.7KHz 60Hz signal with RGBHV, then I think this should work. I can't advise on the actual connectors at the monitors, especially when I don't own them, but for my setup, it would work with my OSSC and SCART TVs, where I made my own SCART cable.
 

maxtherabbit

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CGA cards output TTL RGBI, which would not work with an OSSC or RGB SCART device unless it was run through a DAC first
 

Eudimorphodon

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Commodore's 1084 monitors are all, so far as I know, universally switchable between analog RGB and digital RGBI. What varies is the cable you need to hook it up; I believe the "-S" is the one that has separate DIN plugs for RGBA and RGBI; as long as you have the apropos cable for the RGBI port then yes, it'll work fine with a 5155 because the video output on the 9-pin jack is bog-standard CGA. (Literally the same card as you'd find in a 5150 or 5160.)

If I'm wrong and your -S is a variant that uses a single 9-pin jack for both RGB standards and has a switch then that also should work fine with a straight-through 9-pin cable, with one proviso I encountered: if pin 7 on the computer end is connected to something it can cause problems. (Poster child for this: Tandy 1000s.) Don't think it's a problem for IBM CGA cards.
 

s3freak

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I forgot to mention that my cables are completely custom and have circuitry in them, it is not a straight pass through from the CGA card to the OSSC / SCART device.
 

andromeda92

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if I understand correctly I have 4 solutions:

1) buy an IBM 5153 monitor, it's too expensive and you rarely find it.

2) buy a commodore 1084S screen with the RGBI switch

3) Can be bought the MCE2VGA, but it's not sure that it works

4) buy a VGA LCD screen which takes into account 15Khz, there is a list on the internet but it is not 100% sure that it works

All this using a standard CGA cable that plugs into the IBM 5155 grpahic card

For the MCE2VGA, the sedarshop site no longer responds to emails, I do not know if it still exists.
 

s3freak

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I have an MCE2VGA. You plug a CGA cable from the CGA card to the MCE2VGA, then a VGA cable from the MCE2VGA to the VGA monitor. The MCE2VGA is a scan converter, it converts digital CGA, MDA, and EGA signals to VGA compatible analog signals. The MCE2VGA obtains power via a USB mini cable. There are a few reviews on YouTube.
 

kdr

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if I understand correctly I have 4 solutions:

1) buy an IBM 5153 monitor, it's too expensive and you rarely find it.

2) buy a commodore 1084S screen with the RGBI switch

3) Can be bought the MCE2VGA, but it's not sure that it works

4) buy a VGA LCD screen which takes into account 15Khz, there is a list on the internet but it is not 100% sure that it works

There's also option #5, using the (NTSC) composite video output from the CGA card with a TV. This lets you enjoy the "artifact colours" that some games use to get around the otherwise ugly 4-colour CGA palettes.
 

andromeda92

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I have tested using composite, it work fine,but is black and white, may be my tv not support NTSC, is a old tv TOSHIBA 15" with scart, composite, vga output audio.
 

ibmapc

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For the MCE2VGA, the sedarshop site no longer responds to emails, I do not know if it still exists.
You mean THIS ONE?Screenshot 2020-12-08 132301 (2).jpg Looks like it's in stock. I HIGHLY recommend that. I've built and sold many of those from kits and have not received a single complaint. They work very well indeed. I've also dealt with Serdashop and have not had reason to complain. He seems like a straight shooter.

Greg
 

andromeda92

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Yes is this, I think i will buy it.

what is the difference between Normal Firmware (V2.0) or Special Capture Firmware (VGA-COMON-RES) ?
Which one should i take ?

For the programer i think that is blaster which program MCU Altera.
 

ibmapc

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Yes is this, I think i will buy it.

what is the difference between Normal Firmware (V2.0) or Special Capture Firmware (VGA-COMON-RES) ?
Which one should i take ?

For the programmer i think that is blaster which program MCU Altera.
I have no experience with the "Special Capture Firmware (VGA-COMON-RES)". I have modified the original firmware though just to tweak it so that it would start up with settings preset so that it didnnt need to be adjusted for best picture based on my video card and monitor. I would be interested in trying both firmwares and decide which one works best for my own needs.
 

andromeda92

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I should receive the MCE2VGA soon,
but do I have to change the position of the switches on the motherboard (5 and 6) to go out on the CGA on my IBM 5155 ?
Thanks for your help.

EDIT:
I think I found the answer, someone is using the same PC as mine and the MCE2VGA, apparently there is no need to change the position of the switches on the IBM 5155.
 

andromeda92

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The monitor NEC AccuSync LCD71vm is 15khz, spécification:

ANALOG 0.7 Vp-p/75 Ohms
Separate sync TTL Level (Positive/Negative)
Horizontal sync Positive/Negative
Vertical sync Positive/Negative

May be i can connect CGA to this monitor that is TTL without MCE2VGA ?
 

maxtherabbit

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The monitor NEC AccuSync LCD71vm is 15khz, spécification:

ANALOG 0.7 Vp-p/75 Ohms
Separate sync TTL Level (Positive/Negative)
Horizontal sync Positive/Negative
Vertical sync Positive/Negative

May be i can connect CGA to this monitor that is TTL without MCE2VGA ?

no, not directly, but you can use the much cheaper non-scaling DAC type solutions like the gglabs CGA2RGB

you need to be careful not to conflate TTL *sync* (which this display supports) with TTL *video* which it does not
 

andromeda92

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I don't quite understand it, because if sync is TTL, HSync and VSync CGA should work with the screen which takes into account TTL (+ 5v).
R, G, B on CGA is not TTL level, is a signal.
 

Eudimorphodon

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I don't quite understand it, because if sync is TTL, HSync and VSync CGA should work with the screen which takes into account TTL (+ 5v).
R, G, B on CGA is not TTL level, is a signal.

No.

"TTL Sync" means the monitor is happy with signals that use TTL voltage levels (0v - +5v swing, on/off only) on its horizontal and vertical sync pins. This doesn't say anything about the signal levels that are expected for the R-G-B colors. There are other methods for carrying sync to a monitor, say, via 75ohm terminated ~1v composite sync; the TTL sync spec *only* tells you the monitor doesn't expect that.

Feeding the CGA R-G-B signals directly into the monitor without at least some resistors is going to either give you eight *very* "hot" oversaturated colors or it'll damage the monitor. (Possibly both depending how long you do it.) The analog color signals are supposed to be 75 ohm terminated 0v-~0.7v analog signals where the voltage directly translates to the brightness. (On CGA R, G, B, and I are 0v-5v "on" and "off" signals.) If you want to just "test" it you could stick a, I dunno, 600-1k ohm-ish resistor between the output from the machine and the corresponding video input and get a degraded picture missing the intensity input, but at least you won't kill the monitor. To do it "right" you need a DAC that will both correct the voltage differences and incorporate/gate the intensity input to give you the full/correct 16 colors.
 
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