Reviving an old Sun Sparc-4 VME computer

Dave Erickson

suncpu

First Look

I recently bought a Datacube MaxBox VME chassis plus a bunch of Datacube boards. It came with an added bonus: A SparcStation Sparc-4 VME CPU, an S-Bus graphics card, and 2 extra memory boards. How did the memory cards cable to the CPU? I looked at the VME backplane, and there were wire-wrap wires connecting the 32 pin A and C rows across the first 4 slots.

Here's what I know about the boards:

Sparc-4 CPU board
 SBus frame buffer card
At 1 bit / color, 2Mb / 3 = ~700Kpix, so ~1000 x 700. Each of RGB signals has an L-C-L-C low-pass filter.  I can't see how it wold give more colors than 3 bits. Magic Video Tricks? I thought I knew them all. A 13W3 TO VGA adapter is available from Monoprice: 100071 Sun 13W3 to HD15 VGA adapter, $12
 
2x Sun VME RAM cards
 sun fp

Here are some details about the SBus graphics card from https://everything2.com/title/Sun+graphics+cards
Cgthree: The SBus Cgthree was an un-accelerated color frame-buffer. It provided 8-bit color at up to 1152x900. While a separate SBus card version was produced, this was most often used as the graphics subsystem of the SPARCStation IPX and SPARCStation LX
When I first powered up the system, The LEDs on the CPU board all lit, which was promising. I used this as evidence that the +5V supply was working. I didn't have a sun monitor or keyboard, and hoped that the serial port would output some useful information. I probed a few pins with a scope, and saw RS232 levels on pin 2: +/- 10V. But the signal was just random pulses, not the expected, nice clean RS232 pulses. At that time I measured the VME +5V and discovered that it was +4.2V.  I spent some effort trying to fix the old Qualidyne 750W power supply, but no. I replaced it with a 400W PC supply, and the voltages come up fine.

I looked for pinouts on the Sun HD15 serial ports, and found none. At least I needed GND, TX and RX. I traced the connector signals on the CPU board. They went to two types of chips: 75150 dual RS232 drivers, and 26LS32 differential receivers. I had never seen a differential receiver used as an RS232 receiver, but I checked the data sheet and it can accept + and - voltages. Sure enough, pin 1 is GND, 2 is Transmit and 3 is Receive. I ordered some HD15  connectors and built a simple 3 wire adapter to a 'standard' 9 pin D connector. On the scope I saw nice clean ~100uS pulses on pin 2, indicating that the baud rate was 9600 baud. I connected to a PC running PuTTY, and voila! It output startup messages, and even passed self-test! This is what PUTTY reported.

CPU SUN MICROSYSTEMS SPARCengine 1E 270-8057-02 340-8043-01/51
SPARCengine 1E
ROM Rev. 1.6, 12 MB memory installed, Serial #16777215.
Ethernet address ff:ff:ff:ff:ff:ff, Host ID: ffffffff.
Selftest passed
Initializing 12 Megabytes of Memory ... Completed
Booting from: sd(0,0,0)vmunix
The selected SCSI device is not responding
Can't open boot device
Available Devices:
SCSI disk [disk-device] (sd)
SCSI tape [tape-device] (st)
vm [network-device] (vm)
le [network-device] (le)
Type b (boot), c (continue), or n (new command mode)
>
Apparently the CPU board has 4MB RAM, and the other 2 memory boards have 4MB each, so 12MB total. And the MAC address is dead, indicating a dead battery. Damn Sun for using a 10 year battery. I'll replace the RAM, I think Digikey has them.

I connected an old VGA monitor via a 13W3 adapter, and it displayed video! Hooray! It showed that since there was no keyboard, it would use the serial port instead!

sun


To make these boards work as a real live Sun Sparcstation1, they need:
 If I wanted to just run Linux, I'd use a RPi. I'm not sure exactly what I'll do with this system if I ever get it working. But I do know that at Datacube, when we were all running Sun 3/50s and 3/60s and IPC desktops, our software group had a single Sun 3/110 with VME. Our bench and test machines were mostly Force CPUs running os9. A Sparc with VME was what we all lusted after. If I ever want to actually use the Datacube hardware and Install ImageFlow, a proper VME CPU will be needed. If nothing else, it will be interesting to bring this CPU back to life. Maybe sell it?

Fortunately, SCSI to SD-Card adapter are available that can replace both the Hard Disk and the CDROM for installing SW. I bought a RabbitHole ZuluSCSI RP2040 kit  for $49. It was recently redesigned to replace the original, but now unobtainium, STM32 processor with a RP2040. Thanks to Martin for helping find this, and for finding SunOS and Solaris distributions. Apparently SparcStation1 can use any SunOS and up to Solaris 7. It still needs a SCSI HD50 to ribbon-cable 50 pin adapter.

11/22 Update

I got the battery backed SRAM, the Rabbithole Zulu, the 50 pin SCSI cable, 50 pin ribbon, 50 SCSI to ribbon adapter. Plugged the SCSI stuff together, downloaded a Solaris ISO, but the CPU still doesn't see the SCSI stuff. I haven't yet set up the SRAM. That's another project.

I used the instructions at http://www.obsolyte.com/sunFAQ/faq_nvram.html to set up the EEPROM. It seems to remember the MAC address OK. Still no SCSI though.

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Last Updated 11/25/2022