As promised... 

I was fortunate enough to get a hold of some MVME-224A memory boards 
recently.  Unfortunately, I found that configuration information information 
is somewhat difficult to come by.  Fortunately for me, a very kind 
researcher at one of the US national labs (name withheld because he didn't 
give me permission to publish it) did me the great favor of sending me an 
old copy of the MVME224A manual.  I'm in the process of getting it scanned 
and put up on my web site, but here is a quick and dirty digest.  I'll 
announce when the scans are up. 

Bear in mind that I am a VME novice, so I might not understand everything 
yet.  FWIW...these instructions yeild working memory boards, at least, on my 
Heurikon V532 (aka VME/532, a NS32532 processor).  I haven't tried it on my 
MVME177 yet.  I also don't have a VSB capable system, so I haven't tested 
that. 

These instructions assume you are holding the board straight up with the VME 
connectors facing down. 

Jumpers 

Jumper	Description				Default
J1	VME Interleave Select			1-2,3-4
J2	VMEbus Lock				no jumper
J3	Read Cycle Access			no jumper
J4	Address Size				no jumper
J5	VSB Interleave Select			1-2,3-4 

J1 & J5 - 2 Board Interleave 

Apparently, there are some systems which can interleave access between two 
224As over the VME or VSB bus.  There is no doco as to what systems they 
are, however.  But if you know what this means, you can enable this by 
moving both of these jumpers from 1-2,3-4 to 1-3,2-4.  BTW...enabling this 
implies disabling VSB block transfers.  Nope...dunno how bad that is. 

J2 - VMEbus Lock 

Enable support for the VMELOCK signal.  According to the doco, this is on 
the MVME130, MVME131, MVME135 or MVME141, at least.  Apparently, this 
improves performace of the VSB bus. 

J3 - Read Cycle Access 

Err...this has to with VSB memory access timing.  I need to read more about 
the VMEbus before I understand exactly what they are getting at.  Apparently 
the default is safe. 

J4 - Address Size 

the default allows 32-bit or 24-bit addressing.  With the jumper installed, 
it only allows 32-bit addressing. 

Switches 

There are 3, 8-position switches at the top of the board.  The "on" setting 
is logical 0.  The VMEbus addresses are controlled by S1 & the first 4 
switches on S2 (S2-1 thru S2-4).  VSBbus addressing is controlled by S3 and 
the the last 4 switches on S2 (S2-5 thru S2-8).  This gives 12-bits of 
addressing information per bus running from A20 to A31.  For VME, the LSB 
(nee A20) is S1-1 and MSB (nee A31)is S2-4.  For VSB, the LSB is S2-5 and 
MSB is S3-8. 

Thus: 

A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31 Address (hex)
0   0   0   0   0   0   0   0   0   0   0   0   00000000 (base)
1   0   0   0   0   0   0   0   0   0   0   0   00100000 (1MB)
0   1   0   0   0   0   0   0   0   0   0   0   00200000 (2MB)
1   1   0   0   0   0   0   0   0   0   0   0   00300000 (3MB)
0   0   1   0   0   0   0   0   0   0   0   0   00400000 (4MB)
.
.
.
0   0   0   1   0   0   0   0   0   0   0   0   00800000 (8MB)
.
.
.
etc. 

Ken Seefried
ken@seefried.com