Sun 3/80

April 26, 2022

Sun 3/80

I have the board set from one of these and hope to play with it someday. One board is the video board, which I will almost certainly never use. The other has the CPU, memory, network, and IO.

Two things make it particularly interesting. First, it uses the MC68030 cpu. Second, it is one of the last m68k machines Sun ever made.

From the hardware FAQ:

Processor(s):   68030 @ 20MHz, 68882 @ 20 or 40MHz, 68030 on-chip MMU,
			3 MIPS, 0.16 MFLOPS
        CPU:            501-1401/1650
        Chassis type:   square pizza box
        Bus:            P4 connector (not same as P4 on 3/60)
        Memory:         16M or 40M physical, 4G virtual, 100ns cycle
        Notes:          Similar packaging to SparcStation 1. Parallel
                        port, SCSI port, AUI Ethernet, 1.44M 3.5" floppy
                        (720K on early units?). No onboard framebuffer.
                        Code-named "Hydra". Type-4 keyboard and Sun-4 mouse,
                        plugged together and into the machine with a small
                        DIN plug. Boot ROM versions 3.0.2 and later allow
                        using 4M SIMMs in some slots for up to 40M.

My notes (based on the board I have):

mc68882rc20 math coprocessor
am7990 "lance" network chip
16 slots for ram modules
AT27C010 eprom
the usual clock/nvram chip with battery

The connectors on the back panel are:

50 pin "micro" scsi
ethernet AUI
9 pin serial B
25 pin serial A
25 pin parallel
round "DIN" type 4 keyboard connector

Disks

On the board (inside) is a 34 pin connector (no doubt a floppy).
Also there are two 50 pin SCSI connectors with power connectors nearby.

Memory

As for memory, you could load it up with 16 modules of 1M each. That is the simplest thing to explain.

Place the board with the connectors towards you. This will cause the memory slots to lean away from you.
You have 8 on the right and 8 on the left.
Let's number then from 1 in the front (close to us) and 8 in the back (far away).

To install 4M of ram you put ram into slots 1 and 5 on the left and right.
To install 8M of ram you put ram into slots 1, 3, 5, and 7 on the left and right.

You can use 4M modules, but apparently only in the first two banks.
What is a bank? We have 4 banks.

If we load 4M modules into banks 0 and 1, then 1M modules into banks 2 and 3, we get 4*8 + 8 =32 +8 = 40M.

bank 0 = slots 1 and 5
bank 1 = slots 2 and 6
bank 2 = slots 3 and 7
bank 3 = slots 4 and 8

I don't know what sorts of RAM modules I have, but I have a bunch stored with the Sun3 that I can play with.

Jumpers

I describe the jumpers as they actually are on my board:

J1000	1-2	OUT	Watchdog reset(test)

J020	1-2	IN	68882 20MHz
        2-3	OUT	68882 40MHz

J043	2-3	IN	RS232C (-12V)
J043	1-2	OUT	RS423 (-5V)

J044	2-3	IN	RS232C (-12V)
J044	1-2	OUT	RS423 (-5V)

I don't see myself needing or wanting to change any of these jumpers.

The NVRAM

You can do some surgery on the NVRAM and remove the dead battery bonded on top. This exposes two metal strips. One is ground (it goes to pin 12?) Figure out a way to connect a new 3V lithium battery. Perhaps a coin cell in a socket!

Connect a serial terminal to port a (25 pin) 9600 baud, 8 bits, no parity. L1-A on a real keyboard gets you to the PROM. Once there, see these notes.

Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org