Upgrading an R4400/200 IP19 to R4400/250

What you need:

• full size (ie. 14 pin DIP) 125MHz oscillator - must be 5V, HCMOS/TTL, tristate*. I used an ecliptek EH11TS 125MHz - see Ecliptek's great oscillator web site for more details.
• 250MHz CPU(s)
• 250MHz IP19 PROMs (one for each CPU) - 070-1386-001
• Jumpers
• A large pair of locking pliers as we'll be using skywriter's socket trick to extract the R4400/200 CPU(s).

The images in this section show an R4400/250 IP19 (030-0804-00x) and were taken by Joerg Gerigk and Reinhard Wolf.
 

• Use the skywriter socket trick to extract the R4400/200 CPUs and replace them with the R4400/250s. Note carefully all the details skywriter's description - especially those relating to the heat sink pad.

 
• Replace the R4400/200 PROM(s) (070-1277-001) by gently extracting each one using an appropriate chip puller and replacing it with an R4400/250 PROM (070-1386-001).

 
• Place an appropriate 125MHz oscillator (specs above) in the spare oscillator socket at location H5K7 and a jumper on the pins at location G6K6

 
• Set or make sure that there are jumpers on the pins at the following locations:

 
• H2D7
• H2D8


  Location of H2D7 and H2D8
 

• F7H8
• F8H6
• G9I5
• G9I6


  Location of F7H8, F8H6, G9I5, G9I6
 

• F8M5
• F9M6
• N3P3 - one jumper as follows: (front of board) o  o-o (backplane side of board)


  Location of N3P3 (the N is covered by a sticker)

• Should be no jumpers on the pins at the following locations:

 
• B5P3
  
  

  Location of the B5P3 (the B is covered by a sticker)

Here's the relevant section from a hinv -v:

CPU Board at Slot 2: (Enabled)
  Processor 0 at Slot 2/Slice 0: 250 Mhz R4400 with 4 MB secondary cache (Enabled)
  Processor 1 at Slot 2/Slice 1: 250 Mhz R4400 with 4 MB secondary cache (Enabled)
  Processor 2 at Slot 2/Slice 2: 250 Mhz R4400 with 4 MB secondary cache (Enabled)
  Processor 3 at Slot 2/Slice 3: 250 Mhz R4400 with 4 MB secondary cache (Enabled)
CPU: MIPS R4400 Processor Chip Revision: 6.0
FPU: MIPS R4000 Floating Point Coprocessor Revision: 0.0

Also performed the same upgrade to another 4 x R4400/200 on 23rd July 2000. Both boards are running just fine at 250MHz!

Upgrading an R4400/150 IP19 to R4400/200 or R4400/250

Note: You must have a 3.3V CPU board to try this!!!!

Same equipment and procedure as above. Unfortunately, the upgrade doesn't seem to work on the IP19 2 x R4400/150 (030-0374-008) that I have: a PROM exception is generated in the IP19 PROM just after the secondary cache is tested. The machine drops into POD mode and that's that. I'd be interested in hearing about experiences with other R4400/150 IP19s.

Fortunately, the board can be restored by removing the PROMs, jumpers and oscillator and reinstalling the R4400/150 PROMs. The R4400/250 and 200 MHz CPUs seem to behave just fine when underclocked so if you don't feel like replacing them then its probably safe to just leave them.

Contributors

Contributors without whom this would not have been possible:

• Ben Cannon
• Michael Paradiso
• Skywriter (aka Mr Nutty :-)) - see http://www.reputable.com/~skywriter
• Greg Douglas @ Reputable Systems: provided the R4400/250 cpus for both board upgrades
• Dan Narasky @ MCE: provided the IP19 R4400/250 PROMs
• Joerg Gerigk/Reinhard Wolf: invaluable information and encouragement plus photos of jumper locations on the R4400/250 IP19.