Interface Overview

First, let me get some Terminology out of the way:

• I will refer to the Commodore PET / CBM computer simply as the PET. That may not be technically correct, but that's what I'll do because it's short and sweet.
  
• The PET's IEEE-488 port will be called GPIB by me. (You don't call your FireWire port the IEEE1394 port, do you ?)
  
• The interface's RS-232 Serial Communication Port will be called the Serial Port.

Now for the Interface Specifications (preliminary):

The interface has 4 connectors:

1. GPIB (Female IEEE-488, like at the back of a CBM 8050 disk drive)
2. IDE (40 Pin male dual row pin header receptable, like on a PC's motherboard)
3. Serial (9-Pin female Sub-D, like found on a PC, except female)
4. Power (PC Power Supply style, uses 5 Volts DC regulated)

Hookup is simple: Connect the IDE drive to the interface using a standard 40-pin ribbon cable, and to it's power supply. Connect the PET to the interface using a standard PET-to-IEEE-Device cable (or daisy-chain cable). Hook up power to the interface, and that's all she wrote. The serial port stays unconnected for the moment.

After configuration and formatting of the drive, you should be able to access the IDE drive using standard Commodore BASIC commands. Esoteric commands (block-read/write/execute) may not be supported. There will defenitely be support for PRG files, and probably SEQ and REL files.

More on the Hardware:
The interface circuit consists of a Texas Instruments microcontroller (CPU), Texas Instrument GPIB driver ICs and an RS-232/TTL level shifter. Together with the 4 connectors mentioned earlier, they are incorporated on a double-sided circuit board approximately 3" by 3" in size.

There are no SMT components used.

Power must be supplied from an external 5V DC power supply (that is not part of the interface).


The Serial Port:
This is a freebee, so to speak. It's simply an RS-232 port (no handshake lines, just RX and TX) that can be used by the PET to talk to a modem or any other RS-232 device that doesn't absolutely require hardware handshake.


Configuration:
Initially, there was going to be a jumper on the board, and configuration was going to be through the Serial port. I threw that out, accidentally, when I routed some traces on the circuit board to make the board smaller, and I forgot to put the configuration jumper back in. I realized this about 3 days after placing the order for the first batch of prototype circuit boards. So, I figured that configuration through the GPIB port is just as simple. All you have to know is the initial device number (which will be 8), then you'll be able to send commands to the interface to assign different device numbers to it (they will be stored in the interfaces flash memory and are restored upon reset).