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12MB Ram Issue

Started by Arcadia, October 28, 2019, 10:00:29 PM

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Have an ACE HD with 1mb expansion and EXPERT HD, good power supplies, replaced batteries and cleared SRAM's – have been using them both in their standard 2mb configurations for some time with no issues.

Picked up a XSIMM10 and XSIMM10ss to take them both up to 12mb, can configure boards as 2MB and when powering on "Insert Disk" prompt comes up, boot Memtest68k reports total 4MB as expected and completes full memory test and pass, configure boards for 8MB and when powering on "Insert Disk" prompt comes up, boot Memtest68k reports total 10 MB and completes full memory test and pass.

Now the issue, configure boards as 10MB and when powering on "System boot failure, please reset" message comes up, if you put in the Memtest68k disk and reset it will boot and reports total 12MB and completes full memory test and pass.

Just to mention have been configuring switch and setting up the boards correctly, also have tried boards in each machine and different slots, this being repeatable on both machines.

So at 12MB the "System boot failure, please reset" message comes up, will boot disks fine if you insert disk and reset.

Remember reading somewhere that machines below the PRO level would only go to 10MB, is that true ? – thought all X68000 could go to 12MB, also why would Memtest68k be reporting full memory and completing test, if you leave the disk in and reset.

Has anybody else had this issue ?


Since the computer is correctly booting from the floppy with 12 megs, then your configuration is fine.  I suspect that either your hard drive is booting an older version of Human68k than what's on the floppy, or there's a driver loading in the hard drive's CONFIG.SYS or AUTOEXEC.BAT that's making the system crash.


Thanks for the reply.

The EXPERT HD has no hard drive, set memory expansion for 2mb, power on, insert disk prompt comes up, run memtest disk, reports 4mb, configure for 8mb, disk prompt, run all tests and reports 10mb.

The only issue is when configured for 10mb, when powering on machine the error reset machine message comes up (if you reset the machine with memtest disk in floppy drive, it will boot, complete all tests and report 12mb).

So the machine is just being turned on, nothing else is getting loaded, thinking further it is hitting A00000 memory address space when setup up for 10mb, though you get the error, when resetting with floppy disk in the drive everything checks out.

The ACE HD has a hard drive and was booting fine with expansion set for 10mb (total 12mb), it was only out of interest that I checked it was happing on this machine by disconnecting the hard drive and clearing sram of the boot loader, that I found it did the exact same thing as the EXPERT HD when turning on to boot from a floppy disk drive.

Maybe something in earlier versions of the boot rom causing the issue, maybe a setting in switch is required ?


You sure you have the right simm modules inserted in the XSimm10?


there is a bug in the 1.0 IPL that affects 12MB operation, reducing to 10MB or upgrading the IPL roms to XVI may be the only solution, either that or part of your ram is faulty.


Yeah, now that you mention it, i remember something like that being the case back when i had an xsimm10 in my expert. I think that's why i sold it.



Thanks for your post, have configured both XSIMM's for 8mb (giving total 10mb with system 2mb), all ram was passing tests. Good having it confirmed that it is a rom issue, quite happy to live with 10mb and not go through with a rom swap.


Do you have the configuration details for the XSIMM10ss? Is it the same as the earlier XSIMM10 (the fact it has the pair of 72pin simm sockets has me unconvinced).