how do i connect a vic 20 to a votrax type n talk?

[Snogpitch]

You could try hooking up your Vic20 to another computer like I did earlier and see if you get communication going that way.

[srowe]

Try looping back Tx and Rx and checking you can receive what you send. This will confirm the VIA and the level shifter are working.

[OneSwitch]

Thanks for getting back. I've managed to pin a little more down.

Using a DB25 straight through fully wired cable, I've managed to get an Apple II speak to the Votrax: https://www.youtube.com/watch?v=atRAH0JYUYI

Not perfectly, but not far off it. That's at 9600 baud.


Now I'm wondering if the VIC-1011A is faulty (although it's nearly mint condition), and I still don't know if I should be using a straight-through DB25 or some form of Null modem cable (how bloody confusing it was back then). Does anyone know?

I could check with a Commodore 64 (hoping to get one back soon) as the VIC-1011A is supposed to work on that (I only have one power supply though). Any recommendations for checking via a C64? Any software out there that does the same sort of thing as the Scott Adams games?

[srowe]

Buy or make a loopback adapter, I think you just need a DB25 male connector and link pins 2 and 3.

Run this program, if the VIC-1011A is working it should print "TEST"

Code: Select all

   10 open2,2,0,chr$(8)+chr$(0)
   20 print#2
   30 get#2,a$
   40 print#2,"test"
   50 input#2,a$
   60 printa$
   70 close2

[OneSwitch]

Thanks for this. Much appreciated.

Looking at this: http://www.ni.com/tutorial/3450/en/ - seems you're right that you should only need to connect pins 2 and 3 together. I typed in your programme (with no cartridge installed)

Code: Select all

10 open2,2,0,chr$(8)+chr$(0)
   20 print#2
   30 get#2,a$
   40 print#2,"test"
   50 input#2,a$
   60 printa$
   70 close2

and linked pins 2+3 via a wire directly into the VIC1011-A. I assume that was correct, and I should have seen "TEST" appear on the screen? Not a sausage though.

I've also tried doing the same test on advice, touching the Vic-20 edge connector user port pins M and C together. Again nothing. Perhaps pointing to a faulty VIA chip (as was also suggested to me)?

[srowe]

Nearly, you need to link B, C and M. If that doesn't work I would say the VIA is faulty.

[OneSwitch]

Done. Still nothing. I've ordered a couple of VIA chips to work with. Thanks massively so far for all the help.

[OneSwitch]

Noticed I have two VIA chips on my board, marked as...

mos
6522
2583

The ones I've ordered are...

mos
6522
4881

I'm assuming the bottom number is the week and year they were made. If they've been tested as all okay, they should work fine would you think?

[srowe]

Yes, "4881" means they were manufactured week 48 of 1981. They're MOS parts, same as original. Some OEM versions do not have open collector interrupt pins.

[OneSwitch]

I've just tried the programme connecting B+C+M together referring to this...



...with said to be tested VIA chips. The keyboard works perfectly by the way no matter which way round I have the chips.

No "TEST" output on the screen still.

Any other thoughts appreciated.

Barrie

[OneSwitch]

One other question. I have a working C64. Should this work with this programme...

10 open 1, 2, 0, CHR$ (06)
20 input a$
30 print#1, a$
40 goto 20

Changing 06 to 12 for 2400 Baud?

Thanks again for any help.

[srowe]

The program should work fine on a C64. I would leave the baud rate at 1200 any faster introduces the risk of problems with the RS-232 KERNAL code.

[srowe]

One other question. I have a working C64. Should this work with this programme...

10 open 1, 2, 0, CHR$ (06)
20 input a$
30 print#1, a$
40 goto 20

Changing 06 to 12 for 2400 Baud?

Thanks again for any help.

You're missing the value for the second register. You need to add +CHR $(0) to the OPEN.

[OneSwitch]

Thanks. On both the C64 and the Vic 20 this programme behaves correctly at 300 Baud (connecting pins 2 and 3 together on the VIC-1011A cartridge).

Code: Select all

10 open2,2,0,chr$(6)+chr$(0): 6 = 300 baud
   20 print#2
   30 get#2,a$
   40 print#2,"test"
   50 input#2,a$
   60 printa$
   70 close2

I get "test" appear on the screen every time I run it.

Anything over 300 baud, and I noticed it started to misbehave. Making me wonder how on earth the Scott Adam's stuff works at 2400 baud.

Anyway, I set the Votrax Talk n Type to 300 baud and tried this programme....

Code: Select all

10 open 1, 2, 0, CHR$ (06)+CHR$(0) : REM 300 BAUD TEST
20 input a$
30 print#1, a$
40 goto 20

And get silence from the Votrax. However, if I turn the Votrax off, I can hear that something is getting passed through to it. If I type something short, I'll get a short crackle. If I type a longer string of characters, I'll get a longer crackle. If I type nothing, I get nothing. The speaker hums a bit throughout when off.

If I turn the Votrax back on, nothing. This is the same for the Scott Adams games. If a load of text is produced, I'll get a longer crackle out from the (turned off) Votrax. If a short bit of text is sent to the screen "e.g. I don't understand you, what shall I do now?" it's shorter. Any ideas?

So strange that the Apple II is communicating, but the Commodore's are not.

[srowe]

The Votrax probably won't transmit anything so line 20 needs changing to

Code: Select all

20 a$="some text"

I don't know what the data format is though, do you have a manual for it?