These are two pre-production boards. The first one is Revision 1 and the second is an earlier revision (although it says 3 on the board). The first one uses ZIP memory while the second uses socketed DILs.
These two are both revision 3 boards. The first one is possibly a pre-production unit, as it is missing the boot ROM and the FPU.
Hi Res Version of Image 1 (2000 x 719)
|FPU:||68881@14Mhz (PGA). Can be changed to a faster component if a separate crystal is installed|
|MMU:||External 68851 (PGA)|
|Ram Type:||ZIP Chips (prototype versions use DRAM Chips with sockets)|
An accelerator for the A2000 which plugs into the CPU Fast Slot. This accelerator also has ROMs to support booting the other official Amiga operating system called Commodore Amiga UNIX (Amix). In order to use AmigaOS V2.0+ you need at least version 6.6 of the A2620 ROMs, but preferably V7.0.
|J302||Use 4 Layer (use with German V4.0 A2000 motherboards)||Disable 4 Layer|
|J200||FPU clocked at the same speed as the processor.||FPU clocked independently of the processor. (Separate crystal required)|
|J301||4MB RAM Installed||2MB RAM Installed|
|J303||Disable Memory||Enable Memory|
|J304||Autoboot Amiga UNIX||Autoboot AmigaOS|
|J500||RAM Timing 80ns||RAM Timing 100ns|
Thanks to "The Man" and Dave Haynie