What are my upgrade options for a DDA-06 Board?
The DDA-06 offered 6 analog output channels at 12-bit resolution with channel by channel switch selectable output ranges of 2.5, 5 or 10 volts in both bipolar (-2.5 to +2.5) or unipolar (0 to +2.5). Alternately, channels could be used together with an external power supply to control a 4-20mA current loop.

Additionally, 24 lines of digital I/O were provided via an 8255 chip (PIO-12 equivalent).

Any upgrade or board replacement should be carefully planned. Often times software and cabling changes are required. Sufficient time should be allowed for complete understanding of the existing system as well as testing of the migrated system to fully discover any subtle differences. Study the documentation for your current system (or reverse engineer it from the wiring and source code) to determine which features of the DDA-06 board are actually in use by the application. Often, only a portion of the board's features are required, so board replacement purely on feature specifications can be misleading.

Upgrading to PCI cards: Keithley offers an 8 channel and a 2 channel analog output card in PCI form factor.

The KPCI-3130 offers 8 analog outputs and 32 lines of digital I/O. The KPCI-3132 has 2 analog output channels only.

For applications which use the channels for 4-20mA control, the KPCI-3130 Series offer an advantage of no external power supply is required. Each channel of a KPCI-3130 board can sink or source up to 20mA of current.

The KPCI-3130 Series make use of the mini-centronics connector (IEEE-1284-CC) rather than a DB37, so cabling changes will be required.

A rewrite of the controlling software will also be necessary. Keithley's PCI cards ship with Windows based DriverLINX support only.

PCI cards are typically memory mapped rather than I/O mapped. Controlling a PCI card from a DOS environment will require use of 32bit DOS extenders for access to the 32bit memory space of the board's registers. Your programming language needs to be able to access the 32bit registers of the card. Furthermore, PCI boards are Plug-and-Play devices so do not have base address switches to control what addresses they inhabit; your program needs to be able to enumerate the PCI bus to detect the card and to read out the assigned address configuration.

Register level control of PCI cards requires a significantly different skill and tool set than was required for ISA boards and often is done with third party tools like WinRT to gain real mode access into 32bit memory space.

Upgrading to other ISA cards: The DDA-08 could be used to substitue for the analog output channels. While the DDA-08 uses the same type of connector as the DDA-06, the pinouts are different so cabling changes will be required. Also, the register map of the DDA-08 is different so programming changes will be required.

If the digital I/O of the DDA-06 are required, then a second board such as the PIO-24 (or KPCI-PIO24) will be required.