[hatari-devel] TT hardware memory information

["Roger Burrows" <anodyne@xxxxxxxxxxxx>]

Just posting some TT hardware info as it comes my way (as I try to get EmuTOS 
to run on real TT hardware).

ST-RAM memory support
---------------------
There are 3 valid ST-RAM configurations:
1. 2MB: this is socketed memory on the motherboard
2. 4MB: this adds a 2MB daughter board above the socketed memory
3. 10MB: this adds an 8MB daughter board above the socketed memory

Memory controller values (i.e. what gets written to 0xff8001, and stored in the 
byte at 0x424 by TOS/EmuTOS):
1. 2MB: 0x05
2. 4MB: 0x05
3. 10MB: 0x0a

These values are from live systems, and are confirmed by TOS3 disassembly.

TT-RAM refresh rate
-------------------
During initialisation, TOS3 does the following move:
	move.w	#0x0000,0xffd000e0
This apparently causes a bus error, since the code sets the bus error vector to 
point immediately after this instruction.  According to this document:
	ftp://ftp.lip6.fr/pub/atari/Docs/hardware.txt
$FFD000xx-$FFD000xx: Set FastRAM refresh rate and generate a bus error

Roger