RS-232 mod for C1P

[lowrybt1]

Hello,

I'm trying to restore\reconnect a bi-directional RS-232 port to my C1P. It has all the necessary electronic components but wiring between the 600 Board and the port is messed up. Can anyone point me in the direction of a clear explanation (and schematics) for that mod?

Thanks, Tom

[MK14HAK]

See MarkCsele's site for some good RS232 notes:

Connector J3 Wiring (for Cassette Tape operation):
•Jumper J3 Pin 5 to J3 Pin 6
Connector J3 Wiring (for RS-232 operation): •Jumper J3 Pin 4 to J3 Pin 6
•J3 Pin 2 (RS-232 Out) to DB-9 Pin 2 (Transmit to PC)
•J3 Pin 3 (RS-232 In) to DB-9 Pin 3 (Receive from PC)
•Board Ground to DB-9 Pin 5 (Ground)

J3 4 - 6 is the connection often missed

Mike

[dave]

Whether you hook up the serial port directly or go for a USB<->UART adapter, you will want to increase the baud rate from 300, to make transfers bearable. The 6502 at 1MHz can support in excess of 9600 baud. For the 600 board, the clock is derived from the master timing chain. The 3.932160 MHz clock is divided down to provide timing for the video circuitry as well as the ACIA. U57 and U63 form a divide-by-24 counter to provide the 16x serial clock. The input to this 24-pin divider is pin 2 of U57, which is normally connected to pin 14 of U59, the div32 tap, which yields a baud rate of 300 bps. To get 9600 bps, you will want to drive pin 2 of U57 directly from the master clock signal, pin 3 of U58. This involves cutting the track between U57 pin 2 and U59 pin 14, and jumpering U57-pin2 to U58-pin3 with a short length of wire.

The above assumes a rev B 600 board.

Good luck,

Dave

[BillO]

POKE 61440, 16 should get you 4800 baud IIRC. That sets the ACIA to divide by 1, rather than divide by 16.

POKE 61440,17 will set it back to 300 baud.

[lowrybt1]

BillO,

4800 without jumpers and cutting traces ??

[BillO]

Yep, try it!

[Jeff]

Tom, were you able to get the RS-232 working or did you go with a UART to USB solution?
I picked up a couple of the UART to USBs and I'm planning on hooking one of them up to my superboard tomorrow.

/Jeff