Hardware I.P.B. 4068

With the introduction of the new Token Ring LANstation, the motherboard revision level will move to 'F' and the power supply rating will be upgraded to 40 Watts. Externally there is little difference but internally some changes to working practice may be required.

The power supply top cover has been extended to cover the hard disk drive bay. In order to gain access to the hard disk drive the PSU cover must be removed exposing the high voltage sections of the supply. Always disconnect the mains supply before removing the power supply and hard disk cover. Do not test a hard disk drive with the power supply and hard disk cover removed.

The standard motherboard does not now have a resident network adapter. All network interface modules are installed by selecting the appropriate daughterboard. The four interface modules are :-

Token Ring	Available Now
Unshielded Twisted Pair	Available Q1 1992
Thin Wire Ethernet	Available Q1 1992
Thick Wire Ethernet	Available Q1 1992

The Token Ring adapter supports a ring data rate of either 16 Mbits/s or 4Mbits/s. The rate is set by a switch on the adapter daughterboard. The default setting is 16Mbits/s. If you need the 4 Mbits/s setting (for example, if your network includes unshielded cable), move the red switch marked SW1 on the adapter daughterboard to the front on the machine.

The adapter supports either a 16-bit or 8-bit adapter-to-processor interface width. The interface width is selectable by means of the SETUP diskette supplied. The owner's handbook states (on page B/12) that the default width is 16-bit. In fact the default width is 8-bit, which is the setting that must be used when running IBM network software (for example, the IBM LAN Support Program).

If the 16-bit setting is used with IBM's DXMCOMOS.SYS IEEE 802.3 driver, the following error message appears :-

DXMCO 10E:	Invalid shared ram address
	Error in loading - Press F1 to continue

The 16-bit interface width can and should be used with none-IBM software such as Novell NetWare or Microsoft LAN Manager, as this gives noticeably better performance.

The revision 'F' motherboard will be available in 16MHz and 20MHz variants. 16MHz versions will have base memory of 1MB, while 20MHz versions will have base memory of 2MB. In order to cater for the differences in base memory, when adding extra RAM, a new 2MB and 4MB memory daughter-board has been introduced. The choice of memory module will depend on how much motherboard memory you start with. The following table shows the total amount of memory attained using various memory modules:

Memory Modules	LANstation Rev 'F'	LANstation Rev 'F'
Available	386SX-16 (1MByte)	386SX-20 (2MByte)
1 MByte Module	2 MBytes	---
2 MByte Module	3 MBytes	4 MBytes
4 MByte Module	5 MBytes	6 MBytes
6 MByte Module	---	8 MBytes
8 MByte Module	8 MBytes	8 MBytes

If your computer already has a memory module installed, but has not reached the maximum capacity of 8MBytes, you can remove the existing memory module and replace it with one of a higher capacity. Note that whenever you add a module which raise total memory above 8MBytes, the memory in excess of 8MBytes is unusable.

The new 2 MByte and 4 MByte modules have a row of three switches along one edge (1 MByte, 6 MByte and 8 MByte modules do not have switches). The correct position of these switches depends on the LANstation model you have.

If you have a LANstation 386SX-16 (1MByte base memory) all three switches must be in position 1 (that is, to the right as viewed with the switches towards you); if you have a LANstation 386SX-20 (2MByte base memory), the switches must be in position 2 (to the left).