Connecting KTM-2 to SYM-1?

[RetepV]

Hi, anybody have tips for connecting a KTM-2 terminal to a SYM-1?

I have made the cable as in the manual of the KTM-2. I can see (with an oscilloscope) data going out of the KTM-2 and into the SYM-1, but the SYM-1 does not echo anything back. I am using 4800 baud.

I am not sure the VIA's work, but I will switch them and try again.

Also, in the lower left corner of the PCB are 4 copies of the same small circuit consisting of a 2N2222 transistor and some jumpers and stuff. Of two of these, the transistors have been removed. I am not sure of these transistors are necessary.

And finally, the SYM-1 has the 1.0 rom, maybe it should have the 1.1 rom? And does BASIC 1.1 run with the 1.0 rom?

[dwight]

Hi
You should get your hands on one of those RS232 light boxes. This will save you a lot of time. It may be that the transistors are needed. It seems that I remember that these were needed for the RS232.
Also, which KTM-2 do you have? I'm looking for a copy of the ROMs from a 80 column one. I have a 40 column and want to upgrade.
Dwight

[Paul]

Hi,

In answer to connecting the KTM to the SYM, did you jumper pin 5 to pin 4 of the KTM as stated in the KTM book? When you power up the SYM, the display should flash and wait for input from either the hex keypad OR the KTM. Pressing a "Q" on the KTM should display a "." on the screen. The manual also states that if CTS is not asserted (made high), the curser will stop blinking.

If the transistors are on the LOWER left hand corner, they are not needed for the RS-232 port. The parts located on the UPPER left are. Thats the area that contains the RS232 and TTY buffers.

Either SYM monitor chip will work with this terminal. The basic difference between the two versions was to correct some tape functions.

[Paul]

Oops!

I meant the transistors just below the monitor chip. Actually Q29 and Q31 are the RS232 transistors. Q29 is data from the crt (pin 2) and Q31 is data to the crt (pin 3). If you have the SYM referance manual, it also shows how to connect the terminal. In case you don't, here is the pin out

SYM KTM
2 - 2
3 - 3
1,7 - 1,7 = ground
5,6,8 - 5,6,8

Hope this helps.

[RetepV]

dwight wrote:

Hi
You should get your hands on one of those RS232 light boxes. This will save you a lot of time.

An oscilloscope also works . I even have a logic analyser, except that setting it up is a pain. The oscilloscope will do fine.

Quote:

Also, which KTM-2 do you have? I'm looking for a copy of the ROMs from a 80 column one. I have a 40 column and want to upgrade.
Dwight

Sorry, but it's the 40 column one. I'd also like the roms for the 80 column version, so: anyone else?

[RetepV]

Paul wrote:

I meant the transistors just below the monitor chip. Actually Q29 and Q31 are the RS232 transistors. Q29 is data from the crt (pin 2) and Q31 is data to the crt (pin 3).

Hmm. I didn't have time yet to try again, but the transistors should have been there, so I'll solder in some new ones anyway.

Quote:

SYM KTM
2 - 2
3 - 3
1,7 - 1,7 = ground
5,6,8 - 5,6,8

This is exactly how I wired the cable. Unless I made a mistake on the pinout of either the KTM or the SYM. I guess I'll have to take some better measurements and see if the signals from the KTM actually reach the VIA on the SYM.

Thanks so far, people!

[RetepV]

Well, I've got the SYM-1 working with the KTM-2. Turned out one of the VIA's on the SYM-1 was shot. I had one VIA lying around (coincidentally one from 1978 ), replaced it, and there was the prompt .

I have also been fiddling with adding BASIC. Couldn't get it to work at first. Turned out the jumper wires that determine the ROM configuration were making weak connections. Somehow the wire had corroded, I tried to re-soldering them, but the solder just wouldn't stick. So I replaced the wires. And lo and behold, BASIC came up straight away (after typing 'j 0' of course ).

I've got some pictures up at http://www.retepv.demon.nl/gfx/sym-1/.