[Simh] More VAX Simulators

[Matt Burke]

On 11/05/2019 00:29, Tony Nicholson wrote:
> The Ethernet routine in SIMH (vax_xs.c) uses some details from the
> VAXstation 2000 implementation of the LANCE controller chip.  I think
> the same interface is used in the VAXstation 3100 M38 being emulated -
> but I'd need to see a VAXstation 3100 Technical Manual (if it was
> produced).  One I've seen in my Google searches is a EK-A0525-TD
> manual referenced for the 3100 model 40 and 80 but no copy of it seems
> to be available online.

All of the recently added VAX simulators use the same LANCE Ethernet,
which is an AMD AM2990 chip. The only difference between them is the way
that addresses output by the AM2990 are mapped into main memory. The
LANCE is described in section 5.4 of the VAXstation 2000 Technical
Manual (EK-VTTAA-TM-001):

http://bitsavers.trailing-edge.com/pdf/dec/vax/410/EK-VTTAA-TM-001_VS2000_TechRef_Jul87.pdf

Another good source of information is the datasheet for the AM2990:

http://www.sintran.com/sintran/library/libother/extern/AM7990.pdf

These systems were built from many off the shelf parts so DEC technical
manuals are not necessarily required. Devices such as the SCSI
controller for the VAXstation 4000 M60 I wrote entirely using the
datasheet for the NCR 53C94 chip.

Other details such as the address mapping were worked out by looking at
operating system source listings and experimenting with real hardware.

There are schematics available for parts of these systems under:

http://bitsavers.trailing-edge.com/pdf/dec/vax/410/
http://bitsavers.trailing-edge.com/pdf/dec/vax/3100/

Matt

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