How? I tried examining its start address and executing from there but I can't get output at all. How do you specify port 2 rather than port 1? As you know I can't type on port 1.

Tom L

I don't know if you can. Like MBL, it may be hard coded to port 1.

As for your current loop problem, I'm not sure what else to suggest other than sending the card back and I'll do my best to figure out what's wrong with it.

Geoff.

2SIO Woe
 

OK, I was hoping to avoid that but it does seem like it's the only way, given my poor hardware skills. I'll try to get it out tomorrow. Did you include your address on the box? I'm at work right now so can't look at it and of course I was too excited when the box came to check for such details! If you want, send me your address privately.

Thanks, Geoff.

My address was on the box and I also just sent you a PM.

Geoff.

Thanks, Tom. OK, I have RS-232. Thanks for helping me figure that out. But it means that I can't try to replicate your setup on my equipment or offer any helpful suggestions. I'll just fade into the woodwork now..... Sorry for interrupting your thread.

Paul

Hey, no problem! You're lucky to have one of the RS-232 models. Much easier to interface with modern equipment.

Tom L

tty
 

Hi Tom L
I will suggest some things that you can check before sending the board back to Geoff, Most of it is elementary, But that is what usually can trip one up...
trade the 6850's and see what that does, also check for bent pins--
check all Ic's for bent pins..
check that all the resistors , diodes, caps and transistors are in the ccorrect holes and well soldered on both sides...
check that you have it wired right between the jumpers and the connector ( signal table for tty)
switch port 0 to an rs232 and wire accordingly and see if it works as an rs232. then get it to work as an rs232 or if it works switch it back to tty...
that's all I can think of for now....
THANK YOU Marty

If it is a genuine Teletype model 33, then it is 20mA. Teletype did not build any model
33 with RS232. They were all current loop. It would only be RS232 if there was a
current loop to RS232 converter installed inside or outboard somewhere.

Teletype model 43 is possibly RS232... but this is a much more modern "teletype" and is mostly electronic (with dot matrix printhead) rather than the nearly all mechanical model 33.

Chris

Most people didn't buy directly from Teletype Corp. and independent vendors frequently installed an RS-232 interface converter internally at the request of the customer. I'm surprised that, even though the ASR-35 was much more rugged than the 33, many more 33s survive today than 35s (at least on the used market). I suppose it could be because so many more 33s were sold, though.

Tom Lake

What is the current status of the 2SIO? Do you still want me to mail you mine or is Geoff modifying it for 2 RS-232 serial ports?

The other undocumented chip is the MUSIC ROM. Just examine and run at the address of the ROM. It will load the listing byte for byte (from the newsletter) into memory starting at 0000 and begin playing.

I will send the VTL-2 manual to Geoff and Tom.

Here are instructions for the advanced monitor:

;
; Hardware Debug Monitor for 8080/8085/Z80 processor family
;
; This simple monitor requires NO RAM of any sort. You can use it to
; poke around the system as long as the CPU, a ROM and the UART are
; working. (Hint: if the UART is not working, you can use the polling
; by HDM80 to track down its accessing and debug it).
;
; This monitor provides basic read/modify memory, as well as
; Loop Read/Write functions (useful when hardware debugging).
;
; Commands (must be UPPER-CASE):
; Mxxxx - Display memory at specified address
; Displays one line, enter SPACE for another, RETURN to stop
; Exxxx - Edit memory at specified address
; Prompts with location, enter two digit HEX value, then
; SPACE to proceed to next or RETURN to stop
; Gxxxx - Go (Begin Execution) at specified address
; Rxxxx - Perform Loop-Read at specified address (RESET to stop)
; Wxxxx dd - Perform Loop-Write dd -> specified address (RESET to stop)
;
; Build with DDS XASM tools:
; MACRO HDM80.MAC >HDM80.ASM
; ASM85 HDM80 -t
;
; Dave Dunfield - Aug 4, 2007
; Grant Stockly - Nov 22, 2007 - Modified for 2SIO at 0,1
; GETC modified
; PUTC modified
; HINT modified
;
;
cStat EQU $10 (020) 2SIO Status Register
cData EQU $11 (021) 2SIO Data Register