System definitions

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         ttl System Type Definitions for the Positron 9000
         page
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 ifeq CPUType-Positron
************************************************************
*
*     Dynamic Address Translator Definitions
*

***************
*
* Note that DAT.BlCt is also understood by AllProc and
* Chain (in OS9-P2) to be the number of blocks available
* to each task. If less than 64k is available, these
* routines must be modified to put DAT.Free in the
* blocks that can be allocated, and the required values
* into the other blocks, (eg the I/O block), to complete
* the DAT image.
*
DAT.BlCt equ  32         D.A.T. blocks/address space available
*
***************
DAT.BlUs equ  32         blocks available for RAM in address space
DAT.GBlk equ  DAT.BlCt*2 number of graphics blocks

DAT.Blsz equ  $800       D.A.T. block size in bytes
DAT.ImSz equ  DAT.BlCt*2 D.A.T. Image size

***************
*
* DAT.Addr calculates a mask for the top bits of the
* logical address that are mapped by the MMU
DAT.Addr equ  -(DAT.BlSz/256) D.A.T. MSB Address bits
*
***************


***************
*
DAT.Regs equ  $FF80      DAT RAM base address
DAT.MMU0 equ  DAT.Regs+$40 Start of MMU regs
DAT.SBIT equ  DAT.Regs+$48 S-bit register (Read-only)
DAT.Fuse equ  DAT.Regs+$49 Fuse register for delaying switch to user task
DAT.Accs equ  DAT.Regs+$4A Access register
DAT.Task equ  DAT.Regs+$4B Task register address (operate)

DAT.TMsk equ  $0F        bits of register for task number
DAT.Uniq equ  1          bits of DAT Task register are not used for other things
*
***************

DAT.TkCt equ  8          task maps in the MMU

***************
*
* One block number must be guaranteed never to
* contain memory, (ROM or RAM). That block number
* is used by OS9 in the block map and DAT images
* to indicate an unallocated logical block
DAT.Free equ  $015F
*
***************

DAT.BlMx equ  $100       maximum block number
DAT.BMSz equ  $200       Block Map size (one byte per block)
DAT.WrPr equ  0          no Block Write Protect bit
DAT.WrEn equ  $200       Block Write Enable bit

***************
*
SysTask  equ  $80        System Task number
*
***************

IOBlock  equ  $FF        The block number for the I/O

***************
*
* OS9-P1 ColdStart initially sets up the system map
* with RAM block 0 at $0000, a ROMBlock at $E000,
* and the IOBlock at $F000.
ROMBlock equ  $1FE       ROM block mapped in on ColdStart
ROMCount equ  3          number of blocks of ROM to so map in
RAMCount equ  3          initial blocks of RAM
*
***************

ROMCheck equ  Limited    check only top 64k for ROM
RAMCheck equ  BlockTyp   check only first bytes of RAM blocks
LastRAM  equ  $BF        maximum RAM block number



***************
*
* If the I/O is addressed whenever the top
* address lines of the micro, (ie the logical
* bus), take a certain value, rather than being
* addressed through the DAT, then MappedIO must
* be set false (0)
MappedIO equ  1
*
***************
**********
* Several system modules expect to be
* able to abort the startup procedure
* and retry, by jumping through a ROM
* vector (usually the reset vector).
*
D$REBOOT equ  $FFFE      use an unused vector
*
**********

ClocType set  MC6840
*CPort equ $E800
A.Clock  set  $E800
TickSec  set  100        ticks per second
*Cx2Int set 1 CA2 (CB2) interrupt input
*FPort set $FCE0 floppy disk controller
*HPort set $FD00 hard disk controller
DrvCnt   set  8          eight drives
*DPort set FPort
*A.T1 set $FC40 serial port address
*A.T.Init set $15 default ACIA initialisation byte
*A.P set $FC20 address of parallel printer port
*A.P1 set A.T1 address of serial printer port

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