Macrotech Add-In Boards for Alpha Micro

Macrotech's APU Expansion Hardware allows the addition of more APUs  (Asynchronous Port Units) to your Alpha Micro system. Products are designed for the AM-2000M, AM-1500, AM-2000 and AM-3000. The number of ports can be affordably increased from 32 to 256 with the APU I/O Board. Specifications, compatibility and mounting options are listed in the links below. Call Macrotech directly at (805) 532-1391 for discount pricing on products listed in this section.
APU Serial I/O Board  |  APU Rackmount Chassis
APU Mini Chassis  |  Part Numbers  |  Mounting Options

APU Serial I/O BoardAPU Serial IO Board

Get the most out of your Alpha Micro computer system with Macrotech's APU IO Board. This 16 port Serial I/O Card allows you to install up to 256 ports on any VME CPU, the AM-2000 CPU or the VIP2. It can also be run on the AM-350, limited to the number of ports as the AM-358 (32 ports per cable). Up to 16 APU cards can be connected to the AM-2000M, AM-1500, AM-2000 or the AM-3000 without using the AM350. 

Both RS-232 and RS-422 chips are socketed for ease of service. Ejectors on cable connector allow for easy cable removal. To install, simply dial the rotary switch to the correct board number, define the terminal, plug it in and your job is complete.

Expandability, Internal Addressing:
Up to 256 ports (16 APUs) can be plugged into an I/O cable. The I/O bus has 16 logical locations. Since each APU uses one, and each AM-355 uses 3 and each AM-358 uses 4 address locations, the following formula can be used to calculate the total number of APUs that can be added to any I/O cable:
                     # APUs  =  16 - ( 3 x AM355) - (4 x AM358),
where AM355 is the number of AM-355s and AM358 is the number of AM-358s on the cable. Note that removing one AM-355 frees up space for 3 APUs.


APU Rackmount ChassisAPU Rackmount Chassis

The APU Rackmount Chassis is designed to add 80 external ports to the computer chassis, connected to the computer with a shielded cable. Please note that an additional cable kit is required to connect the Rackmount Chassis to the CPU. 


  • 16 I/O cut-outs (= 80 APU ports)
  • Supports 3 I/O bus cables
  • Black anodized rackmount chassis
  • Size: 15.75" H (9U) x 19" W x 6" D
  • Choice of power supply: Regular (60 watts) for APUs only, large (120 watts) for mixing APUs and AM-355s.
  • Power supply:
    Large (120 watts): 12 amps @ +5 volts, 3 amps@ +12 volts, 2 amps @ -12 volts
    Regular (60 watts): 6 amps @ +5 volts


APU Mini-ChassisAPU Mini Chassis

The APU Mini Chassis is designed for the low-cost addition of 32 external ports to the AM-2000M, AM-1500-06, AM-2000-06 and the AM-3000-06. Not designed for the 10 or 21 slot chassis.

The Mini Chassis cable is either plugged directly into the CPU board or into the last connector on the existing I/O cable. The cable is passed out an empty I/O cut-out and into the back of the Mini Chassis. APUs can be mounted in both the Mini Chassis and the computer backpanel.


  • 6 I/O cut-outs (holds 2 APUs)
  • No power supply
  • Dimensions 12" x 7" x 6"
  • Ivory with black anodized I/O mounting panel
  • Two foot shielded cable between Mini Chassis and CPU enclosure
  • For use with AM-2000M, AM-xxxx-06


Microtech APU Expansion Hardware Part Numbers

AM-2000M APU Backpanel MT610-033
APU Mini Chassis with cable K610-030
APU Rackmount Chassis,120 watt power supply, 16 ports MT610-031
APU Rackmount Chassis, 120 watt power supply, NO ports K610-031
APU Rackmount Chassis, 60 watt power supply, 16 ports MT610-032
APU Rackmount Chassis, 60 watt power supply, NO ports K610-032
Cable Kit (external), APU Rackmount Chassis K600-288


APU Expansion Hardware Mounting Options

Mounting on a Computer Backpanel:
The following list gives the number of I/O cut-outs for each type of chassis:

  • AM-2000M has 5 I/O cut-outs
  • AM-2000M with Macrotech backpanel has 6 I/O cut-outs
  • AM-xxxx-06 has 4 I/O cut-outs
  • AM-xxxx-10 has 9 I/O cut-outs
  • AM-xxxx-21 has 15 I/O cut-outs

APU AM-2000M Backpanel:
The APU AM-2000M Backpanel is used to add two APUs to teh AM-2000M Backpanel, increasing the number of I/O cut-outs from five to six.

  • Replaces standard AM-2000M backpanel
  • Provides 6 I/O cut-outs instead of 5 I/O cut-outs


  2000 Macrotech International Corp. All Rights Reserved.
AM-1500, AM-2000, AM-3000, AM-2000M, AM-355 and AM350 are trademarks of Alpha Microsystems.