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VAX 4000/400: KA675 backup cache failure

GanjaTron

GanjaTron

Experienced Member
Joined
Jan 11, 2007
Messages
201
Hi all,

I have a VAX4000/400 I've been trying to resurrect here as a hobbyist project, which issues the following error on powerup:

Code: 
KA675-A V4.8, VMB 2.12 
Performing normal system tests. 
66..65..64..63..62..61..60..59..58..57..56..55..54..53..52..51.. 
50.. 

?35 2 12 FF 0000 0000 02       ; SUBTEST_35_12, DE_B_Cache_diag_mode.LIS 

P1=00000000  P2=00000000  P3=555A55A7  P4=00000000  P5=0000004B 
P6=00009000  P7=00000000  P8=00000000  P9=00000000 P10=00000000 
r0=00000000  r1=AAAAAAAA  r2=55555555  r3=00020000  r4=00000400 
r5=00000000  r6=555A55A7  r7=0001FFFC  r8=7FFFFFFF EPC=00000000 
   SCBB=20053E00     TODR=00000000     ECR=000000CA 
    SCR=0000C000     DSER=00000000   QBEAR=0000000F     DEAR=00000000 
  QBMBR=03FF8000      BDR=B8F90809   SSCCR=00D57770    IPCR0=0000 
   CESR=00000000   CMCDSR=0000C108  CSEAR1=00000000   CSEAR2=00000000 
CIOEAR1=00000000  CIOEAR2=20001F00   CNEAR=00000000    MAPEN=00000000 
  PCSTS=FFFFF800    PCADR=FFFFFFF8   PCCTL=FFFFFC00 
   ICSR=00000001     VMAR=000007E0    VTAG=00051200    VDATA=8ED000FF 
   CCTL=0000004B  BCETSTS=00000000 BCETIDX=00000000   BCETAG=00000000 
BCEDSTS=00000702  BCEDIDX=00000400  CEFSTS=00001220  BCEDECC=00C00340_SBE=D1 
 CEFADR=04000000    NESTS=00000000  NEOADR=E005BD28   NEOCMD=8000FF04 
 NEICMD=00000000  NEDATHI=00000000 NEDATLO=00000000    MOAMR=00000000 
 MMCDSR=01FEEE20     MEAR=08406011_____ADD=21018044     MESR=00000000 
MEMCON_0:7;  0=80000003,  1=81000003 2=82000003,  3=83000003,  4=00000007,  5=00000007,  6=00000007,  7=00000007 
49..48..47..46..45..44..43..42..41..40..39..38..37..36..35.. 
34..33..32..31..30..29..28..27..26..25..24..23..22..21..20..19.. 
18..17..16..15..14..13..12..11..10..09..08..07..06..05..04..03.. 
Normal operation not possible. 
>>>

I understand that this is a problem with the backup (2nd level) cache on the KA-675 CPU board. Can anyone enlighten me as to whether this is a fatal flaw and requires replacing the CPU module?

The reason I'm asking is because I'm new to DEC hardware and the console firmware still executes, which leads me to suspect it's either not fatal, or the console simply bypasses the cache.

Would like some clarification on this before I invest any more time and money in this baby (including an OpenVMS installation).

Many thanks & best regards,

--GT
 
Well this won't be much help, but I have 4 (four!) Alpha CPU boards with dead B-cache. This really seems to plague the more high-end models (AS 1000, AS 4000 here).

It's pretty much dead forever and yes you need to replace the CPU board. You could try booting something though, that won't hurt. Although the chance of success is remote.

Some (Alpha) boards allegedly have a setting (possibly jumper?) to disable the B-cache, but it's gonna be piss slow then of course.

If you can fix it somehow, let me know...
 
Hi Gabucino.

thanks for your reply, looks like it's a common fault with DEC's early SMD stuff then. Do the AS boards also have the CY7C series of SRAMs for the backup cache? Of course the only way to fix this is to (a) identify the faulty chip and (b) exercise your SMD soldering skills! Neither is doable for me, at least with my current gear. :^(

Btw, this particular 4000/400 appears to be a later revision, boasting an "Alpha ready" badge. Not sure if that actually required them to modify the backplane.

See ya,

--GT
 
The AS1K CPU boards have KM68* and TC55* chips. I've thought about going over them with a heat gun :) Maybe sometime.
 
Hi GT

The VAX4000-400 uses the KA670 CPU. The error message you get is:

?35 2 12 FF 0000 0000 02 ; SUBTEST_35_12, DE_B_Cache_diag_mode.LIS

Where ?xx identifies the diagnostic test - (Ref: the DEC KA675 Maintenance Manual)

This appears to indicate that Test 35 is the failing test (the test description is: “Memory byte errors”).

Does the console LED display ?4B ?
If so, then this may be caused by a memory module failure (MS690 board).

Before you consider replacing the CPU module, try removing any unnecessary Memory boards (assuming that your system has more than one). In other words, remove all but the minimum required.

If the fault disappears, you could then, replace with the unused (removed) module to identify the failing one.

The MS690 memories are available in three variations:
-MS690–BA (L4004–BA) 32 MB memory
-MS690–CA (L4004–CA) 64 MB memory
-MS690–DA (L4004–DA) 128 MB memory

KA675 systems allow for any combination of up to four MS690 memory arrays thus providing a memory capacity from 32 Mbytes up to 512 Mbytes.

If it’s not a faulty memoryboard, then the next most likely cause is a faulty CPU board.

Let me know how it goes. If you’d like to drop me a note, I can send you the KA675 CPU System Maintenance Manual.

Good luck,
Dave
 
Hi Dave,

many thanks for the detailed info, I'll try swapping the MS690s next week to check the effect. But isn't the console LED display a single digit? And I did a memtest once (forgot the code) and I think the MS690s passed. Will check if there's any correlation with the b-cache tho.

Thanks & best regards,

--GT
 
Hi Dave,

thanks for the manual, actually already had it. ;^)

The VAX is populated with two MS690-BAs; both pass the A9 memory test suite.
The same B-cache error (35) shows up with either MS690 on its own. The console LED display never gets beyond 9.
At this point it's safe to conclude the CPU needs replacing... :^(

Thanks for the info,

--GT
 
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