SE/30 RAM config mystery / cry for help

#1 Sun, 15 Jun 2008 - 07:11 68kMLA

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.

#2 Sun, 15 Jun 2008 - 08:47 68kMLA

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

#3 Sun, 15 Jun 2008 - 16:32 68kMLA

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

#4 Sun, 15 Jun 2008 - 19:01 68kMLA

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...

#5 Thu, 17 Jun 2010 - 20:31 68kMLA

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

#6 Fri, 18 Jun 2010 - 04:07 68kMLA

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

#7 Fri, 18 Jun 2010 - 04:19 68kMLA

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.

#8 Fri, 18 Jun 2010 - 21:31 68kMLA

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.