Commodore 128 cabling

From: The Adept <>
Date: Tue May 12 19:21:53 1998

R. Stricklin (kjaeros) wrote:

> Hi.
> I picked up a C=128 with a pair of 1571 drives and a 1902 monitor at a
> thrift shop the other day. I'm a bit of a Commodore gumby---I only ever
> knew one guy who had one, and it was a C=64.
> I couldn't find any of the cables when I bought it. I actually did go back
> this morning and found a few of them, so I have a few questions.
> The 1902 monitor has 5- and 8-pin DIN connectors.
> The C=128 has 5- and 8-pin DIN connectors for video, along with a DE9f for
> 'RGBI'.
> The video cable I found has a 5-pin connection labelled 'Computer' and an
> 8-pin connection labelled 'Monitor'. This sounds pretty straightforward.
> So my question is, which jacks are used for what? Will I not be able to
> use 80 column mode with this cable? Should I wire a straight-through DIN-8
> cable and use that instead of the one I have?

You need to use the RGB-I connection for 80 column on the 128. The DIN-8and
RGB-I can be connected simultaneously, output goes to the RGB port if the
40/80 locking key is engaged and the machine is in 128 or CP/M mode. In all
other cases, output is via the VIDEO out or RF out. The 5 Pin DIN you have
is probably for a C64, which uses a 5 Pin DIN for video. (The C64C shares the

DIN8 with the 128).

> What do I gain by using the RGBI connector? Would one of the Tandy RGB
> monitors work with it? The thrift has one, either a CM-3 or CM-5. I forget
> which.

80 column mode is about it. The output is standard CGA/EGA type. There isa
mono signal on one of the unused CGA/EGA pins (don't remember which
one off the top of my head) so you could custom wire that single pin to
a mono monitor.

> Also, I was unable to locate the power supply. I notice it has the same
> connection as my A500 supply, except the switch is on the CPU instead of
> the PS. Could I use the A500 supply on the C=128 until I can dig up a
> C=128 (or even C=64?) supply?

The C=64 uses a DIN connector on the PS rather than the square (POST)
connector of the 128. The pins of the 128 are as follows:
    1: (shield)
    2: key
    3: signal ground
    4: +5V
    5: 9VAC
    6: 9VAC

The A500 power connector should NOT be connected to your 128 or
you will have a serious problem. The 500 uses +- 12V on two of the pins
so you will blow something up.

> ok
> r.
> PS; I'm still trying to find info on that TI-99/4A video cable. (:

 I have a couple of them but don't have info handy, will see if I can track.


Received on Tue May 12 1998 - 19:21:53 BST

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