SE/30 RAM config mystery / cry for help

[TylerEss]

While tinkering with a jailmac SE/30 motherboard and a IIfx ROM SIMM today, I discovered that the "Load Bank A first, larger memory must be in Bank A" restriction of the SE/30 has nothing to do with its memory controller, but to do with the RAM detection routine they use in the SE/30 ROM.

The SE/30 with IIfx ROM SIMM boots and runs fine with SIMMs only in Bank B. It fails to boot with the SE/30 ROM.

By the bye, does anybody have any of the VRAM chips for the SE/30 sitting around? My experiments and intuition tell me that replacing the VRAM chips might fix my jailmac problem.

 

[JDW]

Tyler, please inform us the precise location on the SE/30 logic board where these VRAM chips are located.

 

[equill]

The Texas Instr. chips TMS4461-15NL at UC7 and UC6. See the Bomarc diagram 6 of 6: 'Video processing, GLUE & PAL Section', grid A/B-6/7, for MLB 820-0260-A.

de

 

[TylerEss]

I see that there are some new NEC ones on eBay right now, but it'd be about USD20 and that seems excessive for parts that might not fix a spare board I don't really need...

 

[trag]

There are some on Ebay now for about $6 - $8 total. $3.95 + $1.50 shipping and $1.92 + $6 shipping. The former is new, the latter is used.

http://cgi.ebay.com/ONE-TI-TMS4461-TMS4461-15NL-RAM-IC-BOX-64-/370267157659?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item5635a4749b

http://cgi.ebay.com/TMS4461-12NL-TI-256K-Video-RAM-MB81461-HM53461-53461-IC-/370290762883?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item56370ca483

 

[tomlee59]

Two years after the last post...I suspect that the problem has been solved (or abandoned) by now.

 

[JDW]

Seems like Tyler (the creator of this thread) has fallen off the face of the earth. His last visit here was Aug 17, 2009! So perhaps we will never know.

 

[trag]

Two years after the last post...I suspect that the problem has been solved (or abandoned) by now.

Well, true. But folks sometimes (well, I do sometimes) search the threads for solutions, so updating old threads seems useful even if the original poster will no longer benefit...

On the other hand, a link to an Ebay auction has a decay time of about 90 days, so I don't know how much good I did there, other than to indicate that prices may vary.

On the gripping hand, I have projects backed up from at least two years ago. Anything I was working on two years ago is probably still a current project. So the original poster might still have it sitting around.