My Computer Collection
IBM PS/2 Model 80-311

Photo of IBM PS/2 Model 80-311
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Now, that's a real server :-)

This is a version of the PS/2 80 that was used for network servers (a Novell server in this case). Compared to the first generation Model 80's, it has a new mainboard with a faster processor (20 MHz) that was completely redesigned. It seems that IBM fixed some nasty bugs present in the original 16 MHz board, since Linux runs smoothly on this machine (if you do not regard the lousy performance of the Linux PS/2 ESDI driver ;-). The hard disk equipment - 2 disks with 300 MBytes - was the maximum offered by IBM at that time.

Photo of IBM PS/2 Model 80-311's Innards
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In contrast to the 70 and 115 MByte ESDI disks, the 300 MByte ESDI drives are not IBM-branded. They are Maxtor XT4380E drives, with the usual 'magic IBM tracks' for the type of defect management made by the ESDI controller's hardware.

PS/2's which are that full of cards are rare - however, one of them is not a true adapter. It's the one to which one end of the ribbon cable is tied. This cable and the card are part of IBM's original offering for an external 5,25 inch floppy drive. Since there is no other way to get access to the Shugart bus, an empy frame is plugged into one of the floppy drive bays with a special adapter PCB. The signals run through the cable to the card that is nothing more than another adapter to the external DB37 connector. So much about the darker sides of PnP hardware ;-) The drive itself is a pure 360K drive (IBM later offered 1,2M drives for the PS/2s, which needed a secondary floppy controller for the 300Kbit data rate) and has a monstrous case (see below). It even has its own power supply, though the Model 80's power supply wouldn't have had any problems feeding another floppy.

Photo of IBM PS/2 Model 80-311's external floppy
Click here or click onto the photo for a full size version of this picture.

Photo of IBM PS/2 Model 80-311's mainboard
Click here or click onto the photo for a full size version of this picture.

A closer look onto the main board. The layout has been changed completely... However, this makes it easy to differentiate the 16 MHz and 20 MHz boards: the newer one has the CPU and FPU in the center of the PCB, while they're located at the bottom end of the 16 MHz version.

Processor:
Intel i386DX @ 20 MHz
Coprocessor:
Intel i387DX @ 20 MHz
Cache:
none
Memory:
10 Mbytes (options range from 1M to 8M)
Bus:
8 MCA slots (3x32 bit, 5x16 bit)
Interfaces (onboard):
  • Mouse, Keyboard
  • 1x Serial
  • 1 x Parallel
  • Floppy (1.44M), allows attachment of up to 2 drives
  • VGA
Add-on cards:
  • SKnet MC2+ Ethernet Adapter (3x)
  • IBM ESDI Hard Disk Controller
  • IBM 2-8M Memory Expansion (6M occupied)
  • Future Domain MCS-350 SCSI Host Adapter
  • ELSA Winner/2 Graphics Accelerator
  • Adapter card for external floppy drive
Operating System(s):
  • Linux 2.0 (Slackware-based)
Useful Links:


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©1999 Alfred Arnold, alfred@ccac.rwth-aachen.de