Commodore A590

The A590 is a hard drive controller which connects to the side expansion slot of the A500. It provides both a SCSI controller, and an XT controller. An XT Controller is the very old 8bit IDE standard (not to be confused with ST506). Whilst it uses the same 40pin IDE cable that modern IDE controllers use, you cannot use modern IDE drives with the XT-Controller because they are 16bit. You must use XT hard drives. These were only ever made up to about 80MB in size. There are several versions of the ROMs for the A590, Version 6 ROMs only allow hard drives up to 512MB in capacity. Version 6.6 and 7.0 ROMs have been reported to work successfully with drive sizes up to 9GB but you will need at least OS3.5 to use drives over 4GB.

Download the A590 Manual

DIP Switch:

Switch 1
OFF Disables Autoboot ROMs (Kickstart 1.2)
ON Enables Autoboot ROMs (Kickstart 1.3)

Switch 2
OFF LUN Disabled (One Drive at each address)
ON LUN Enabled (Multiple drives at each address)

Switch 3
OFF Short wait period for drive to spin up. Parity checking enabled
ON Long wait period Parity checking disabled for message in phase

Note: Parity checking is not supported on some Seagate drives. With these drives, set the switch to the ON position. <> Switch 1: Autoboot Enable: If you are using Kickstart 1.3, you can set switch 1 to the ON posistion.This will allow your system to boot from the A590.

Switch 2: LUN Enable: The switch only affects SCSI drives. If you have more than one device at a physical address (SCSI ID), set switch 2 to ON. When this switch is in the OFF posistion, the system only looks for one Logical Unit Number (LUN), or one drive, at each physical SCSI address. When this switch is in the ON posision, the system will attempt to open Logical Units 0 through 7 at each physical SCSI address.

NOTE: Some SCSI drives such as certain Seagate and Epson drives, respond to more than one logical address (LUN). Such drives will appear on the Workbench screen and the Hard Drive Preparation, Partitioning, and Formatting screen in HD Toolbox multiple times, at the same Address but at LUN 0 through 7. If this occurs, set switch 2 to OFF.

Switch 3: Time-Out Length: If you are using a SCSI drive that takes longer than 30 seconds to start up when you turn the system on, such as some seagate drives, you may wish to set switch 3 to ON. When the switch is in the OFF position the time-out period, the time between power-on and when the system checks the drive, is short. When the switch is in the ON position the system will wait a longer time before checking the drive.

Switch 4: Reserved (e.g., don't mess with it!)

Jumper Settings:
Note: The A590 is shipped with all jumpers set to 1
JP1 1 = Amnesia
2 = 512K
3 = 1MB
4 = 2MB
Sets the amount of RAM installed
JP3 1 = XT Drive
2 = SCSI Drive
Set LED for XT or SCSI Drive
JP4 1 = Interrupt 2
2 = Interrupt 6
Note: Do Not Change

Thanks to Andrew Bowers, Mats Magnusson, Eric Schneider, Paul Gable, Thomas Unger and Peter Brachter