Interlan NI1010A/NI2010A Ethernet interface

From Computer History Wiki
Jump to: navigation, search

The Interlan NI1010A and NI2010A are Ethernet network interfaces for the UNIBUS and QBUS respectively. (The two device controllers are very similar in programming terms, so they are covered in this single article.)

They use DMA to transfer data to and from buffers in main memory. They have an on-board FIFO buffer which can hold up to 13.5K bytes of inbound data; the host can pre-queue up to 16 input buffer DMA requests.

The NI1010A is a single hex board. The NI2010A is a quad board, with a large daughter card; they take two slots, but only the mother card has edge fingers to plug in. A grant continuity card is supplied, to plug into the second slot, to carry the QBUS' bus grant lines through the slot.

Their bus address and interrupt vectors can be set via DIP switches on the board (to 7mnnp0, where m can be 6 or 7, and p 0,2,4 or 6; and 0xx0, respectively), but their defaults are 0764000 and 0340.

There are two interrupt vectors; 0xx0 for 'Receive DMA done' and 0xx4 for 'Command done'.

Device registers

The NI1010A controller includes 3 registers, and the NI2010A 4 (the optional extra register is needed because of the larger address space on the QBUS):

Register Abbreviation Address
Control Status Register CSR 764000
Bus Address Register BAR 764002
Byte Count Register BCR 764004
Bus Address Extension Register
NI2010A only
BER 774006

The Bus Address Extension Register was enabled by a switch; i.e. the NI2010A could be set to be identical, programmatically, to the NI1010A, at the cost of not being able to use more than 256KB of main memory.

In the register contents (below), bits which are read/write or unused are shown in normal font, those which are read-only are in italics, and those which are write-only are shown in bold.

764000: Control Status Register (CSR)

XM FUNC CDN CIE RDN RIE STAT
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00

Bits are:

Bits Use
XM Extended address bits A17 and A16
FUNC Command Function Code
CDN Command Done
CIE Command Done Interrupt Enable
RDN Receive DMA Done
RIE Receive DMA Done Interrupt Enable
STAT Command Status Code

Reading the CSR clears the two 'done' bits. The extended address bits are disabled on the NI2010A when the BER is enabled.

Command function codes are:

Code Command
01 Set loopback
02 Set internal loopback
03 Clear loopback
04 Set promiscuous receive
05 Clear promiscuous receive
06 Set receive-on-error
07 Clear receive-on-error
10 Go offline
11 Go online
12 Run diagnostic
15 Set insert source address
16 Clear insert source address
17 Set network address to default
20 Set receive all multicast
21 Clear receive all multicast
22 Perform loopback test
23 Perform collision detection test
30 Report and clear stats
31 Report collision delay times
40 Supply receive buffer
50 Load transmit data
51 Load transmit data and send
52 Load group address(es)
53 Delete group address(es)
54 Load physical network address
60 Flush input buffer queue
77 Reset

Command status codes are:

Code Status
00 Success
01 Success with retries
02 Illegal command
03 Inappropriate command
04 Failure
05 Buffer size exceeded
06 Frame too small
10 Excessive collisions
12 Buffer alignment error
13 No heartbeat detected
14 No CRC error occurred
15 Inappropriate CRC error
16 Last data byte not received
17 Non-existent memory

764002: Bus Address Register (BAR)

BA15 <---> BA00
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00

Write-only register.

764004: Byte Count Register (BCR)

BC15 <---> BC0
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00

Write-only register.

7764006: Bus Address Extension Register (BER)

Unused BA21 <---> BA16
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00

Write-only register.

Note: This register is present in the NI2010A only.