old serial peripherals, e.g graphics tablet, on a mac

[jerwin]

I'm considering getting a graphics tablet for my imac. Not a new graphics tablet; but an old school, serial based digitizer.

Why? The things I need to digitize have very simple geometry, but are too large to fit on a scanner-- or a small, consumer oriented graphics tablet. An 11x17 graphics tablet from the bad old days of computing goes for very little. I've read a few linux oriented columns on how to read the serial data link from, e.g, an old Kurta.

But before I go hunting on ebay, I need a USB to RS232 interface. What should I look for in terms of chipset, driver compatibility, etc?

(And has anyone on this board successfully used a older digitizing tablet on their shiny new mac?)

 

[Fishrrman]

Even if you get the physical interface connected...
... do DRIVERS exist for it?

 

[jerwin]

I'd only need the drivers for the USB interface. It's not as if I plan to use this with adobe illustrator. Instead, I'd write a program to translate the serial data into pen position, and button presses. Something like this:

#! /usr/bin/env python
# Kurta IS/ONE switches
# A:12345678 B:12345678 C:12345678
# DUDDDUUD UDUDUDUU UUDDDDUD (U=UP,D=DOWN)

import serial

ser = serial.Serial('/dev/ttyS0', 9600, 7,'O',2,timeout=None)

while True:

ser.flushInput()
read_chars = ser.read(12) # read up to twelve bytes (timeout)

str = ''
for ch in read_chars:
n = ord(ch) & 0177 # mask out hi bit
if n != 13: # ignore carriage return
str = str + chr(n)

# Output button number, X, and Y
print str[0:1],str[1:6],str[6:11],'\a'

if str[1:3] == '00': # quit for X close to origin
break

ser.close()

Looks far simpler than the InputSprocket driver I had to write to get my cheap MacAlly joystick working on Star Trek: Starfleet Academy