Emu XL-7 & MP-7 User's Group

On 26/05/2019 20:25, smw-mail@... [xl7] wrote:

> Maybe the OS gets the SIMM checksum and looks up the nsame from
> there, if its not on the SIMM.  Maybe its in baby flash?

The ROM name is in the baby flash, offset 0x40 - 0x44.  The SIMM 
checksum is also there (offset 0x00 - 0x03) and the ROM number is at 
offset 0x2f.

Here are the numbers and identifiers that I've extracted from both my 
own ROM dumps, and from the baby flash dumps that are in the Proteus 
group archive.   Note that there *are* some duplicate numbers:

   4 CMPSR
   5 P/123
   6 B-3
   7 XLEAD
   8 QROM   ZR
   9 World
  10 ORCH1
  11 ORCH2
  13 PHATT
  14 XL-7   XROM
  15 MP-7   MROM
  16 SONIQ
  17 PROM1
  18 VROM
  19 DRUM
  64 GRAIL
  65 TeCnO
  66 AOrch
  67 BEAT

User SIMMs are identified with 106 - 119 and "FLASH" in the ROM name.

I didn't quite yet figure out how the CRC32 is calculated so that it can 
compare the value, although I'm still working on it.

I did however discover today that the O/S has a hard limit of 2MB of 
baby flash - it'll report "Invalid" if you perform a ROM check on a ROM 
larger than that.

(technically you can install a larger chip there, but the O/S won't use 
more than 2MB of it).

I also found that the CRC check routine appears to ignore User SIMMs, so 
it's perhaps not necessary to even bother filling that in on those, 
which would be a bonus!

Ray