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'''1700/1750 RAM Expansion Module Users Guide'''

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[[Category:REU_RAM_Expansion_Units]]

----

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The Project 64 etext of the ~1700/1750 RAM Expansion Module User's
Guide~, converted to etext by Frank Kontros <frank@kontr.uzhgorod.ua>.

1700RE10.TXT, November 1997, etext #302#

*********

 1700/1750 RAM Expansion Module
         User's Guide

    For Your Commodore 128


Copyright (c) 1985 Commodore Electronics Limited
All rights reserved

This manual contains copyrighted and proprietary information.  No
part of this publication may be reproduced, stored in a retrieval
system,  or transmitted in any form or by any means,  electronic,
mechanical,  photocopying,  recording  or otherwise,  without the
prior written permission of Commodore Electronics Limited.

This  software  product is copyrighted and all rights reserved by
Commodore Electronics Limited.  The distribution and sale of this
product  are intended for the use of the original purchaser only.
Lawful  users  of these programs are hereby licensed only to read
the programs, from their medium into memory of a computer, solely
for the purpose of executing the programs.  Duplicating, copying,
selling  or otherwise distributing this product is a violation of
the law.

DISCLAIMER

COMMODORE  ELECTRONICS LIMITED ("COMMODORE") MAKES NO WARRANTIES,
EITHER  EXPRESSED  OR  IMPLIED,  WITH  RESPECT  TO  THE  PROGRAMS
DESCRIBED HEREIN, THEIR QUALITY, PERFORMANCE, MERCHANTABILITY, OR
FITNESS  FOR ANY PARTICULAR PURPOSE.  THESE PROGRAMS ARE SOLD "AS
IS".  THE ENTIRE RISK AS TO THEIR QUALITY AND PERFORMANCE IS WITH
THE   BUYER.   SHOULD  THE  PROGRAMS  PROVE  DEFECTIVE  FOLLOWING
PURCHASE,  THE  BUYER  (AND  NOT  THE  CREATOR  OF  THE PROGRAMS,
COMMODORE,  THEIR  DISTRIBUTORS  OR  THEIR RETAILERS) ASSUMES THE
ENTIRE   COST   OF  ALL  NECESSARY  DAMAGES.  IN  NO  EVENT  WILL
COMMODORE   BE   LIABLE   FOR  DIRECT,  INDIRECT,  INCIDENTAL  OR
CONSEQUENTIAL  DAMAGES  RESULTING FROM ANY DEFECT IN THE PROGRAMS
EVEN  IF  IT HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
SOME  LAWS  DO  NOT  ALLOW THE EXCLUSION OR LIMITATION OF IMPLIED
WARRANTIES   OR   LIABILITIES  FOR  INCIDENTAL  OR  CONSEQUENTIAL
DAMAGES, SO THE ABOVE LIMITATION OR EXCLUSION MAY NOT APPLY.


Commodore 128 is trademark of Commodore Electronics Limited.
CP/M is a registered trademark of Digital Research, Inc.
dBaseII is a registered trademark of Ashton-Tate, Inc.



Contents

  1. INTRODUCTION

1.1. What a RAM Expansion Module Is
1.2. Two Ways to Use the RAM Expansion Module
1.3. What Comes With Your RAM Expansion Module
1.4. Suggestions on Reading This Guide

  2. INSTALLATION AND DEMONSTRATION PROGRAMS

2.1. Installing the RAM Expansion Module
2.2. Using the Demonstration Programs
       Booting the Demonstration Disk
       Using the STARTUP Menu

  3. HOW TO USE THE RAM EXPANSION MODULE IN CP/M MODE

3.1. Booting CP/M
3.2. Using CP/M Commands

  4. HOW TO USE THE RAM EXPANSION MODULE IN C128 MODE

4.1. Basic Commands
4.2. Memory Locations
4.3. Example Programs

  5. TECHNICAL SPECIFICATIONS

5.1. Operating Modes
5.2. Direct Memory Access Operation
5.3. Special Features
       Autoload
       Address Control
       Interrupts
5.4. Operation Description
5.5. Timing
5.6. Bank Configuration



1. INTRODUCTION


1.1. WHAT A RAM EXPANSION MODULE IS

A  RAM  expansion  module is a device that allows you to increase
the  available  memory  of  your computer.  Your computer has two
kinds of memory areas, RAM and ROM.  RAM, short for Random Access
Memory, is  for temporary storage.  You can put programs or other
data  in RAM and retrieve them later.  ROM,  or Read Only Memory,
stores  the  operating  system  of  your  computer and may not be
changed.  The 1700 and 1750 RAM expansion modules contain RAM, in
an arrangement called banks.

The  1700  RAM  expansion  module  increases  the  memory of your
Commodore  128  computer  by  128 Kilobytes or K  (for a total of
256K).  The RAM space is arranged in two 64K banks.  The 1750 RAM
expansion  module  increases the available memory by 512K  (for a
total of 640K).  In the 1750 RAM Expansion Module there are eight
64K  banks.  All the instructions for using the two RAM expansion
modules are the same. The only difference between the two modules
is the amount of RAM they contain.

The   RAM   expansion  module  gets  attached  directly  to  your
computer's expansion port.  Once installed, you give instructions
which access the expansion RAM banks. The data can be transferred
immediately   from   the  RAM  expansion  module  into  the  C128
computer's main memory.  No time is lost waiting for a disk drive
to find and load a file.  In CP/M mode of the C128 computer,  for
example,  file  loading  is  10  to  15 times faster with the RAM
expansion module than with a conventional disk drive.

The RAM expansion module contains indirectly accessible RAM. This
means  that programs stored in the RAM expansion module cannot be
executed by the C128 computer until they are transferred from the
RAM  expansion module into your computer's main memory.  The main
advantage of the RAM expansion module is rapid retrieval of data.

Remember, RAM is not permanent storage. If you turn your computer
off any data stored in the RAM expansion module will be lost. Any
information  stored  in the RAM expansion module should therefore
also be saved on disk, to avoid loss of your work.


1.2. TWO WAYS TO USE THE RAM EXPANSION MODULE

You can use the RAM expansion module in two ways:

1) IN CP/M MODE
2) IN C128 MODE

The techniques used to access the RAM expansion module in each of
the  two  modes are different,  but the end result is the same --
you get extra memory.

IN CP/M MODE,  the  RAM expansion module acts exactly like a very
rapid  disk  drive.  Large  application  programs,  such  as word
processors  or  business analysis programs,  can be stored in the
RAM  expansion  module  at the beginning of a work session.  From
then  on,  you indicate to the computer to find program utilities
in  the RAM,  rather than on an external disk drive.  Because the
RAM  expansion  module stores the programs in a form the computer
can  use  almost instantly,  operation of these programs is rapid
and  efficient.  You  will  find  this ability particularly time-
saving  with  programs  that access the disk drive often,  called
"disk intensive" programs, such as dBaseII.

The  CP/M  system  controls the RAM expansion module.  You do not
have to be concerned with the way data is being stored,  or where
in  the  RAM  banks  of  the  RAM  module a particular utility is
stored.  CP/M  remembers  all  this  for  you,  and can display a
directory of currently stored programs or data files.

IN C128 MODE,  you  use BASIC or machine language to perform data
transfers  between  the  main memory of your computer and the RAM
expansion  module's  RAM  banks.  Several  7.0 BASIC commands are
designed specifically to access the RAM expansion module. Machine
language  is  helpful in using the more advanced functions of the
RAM expansion module in C128 mode. Using the RAM expansion module
in  C128  mode requires the user to remember what has been stored
in the RAM expansion module,  and where in the RAM banks the data
lies.


1.3. WHAT COMES WITH YOUR RAM EXPANSION MODULE

Along  with  your  RAM  expansion  module and this manual are two
disks.

One  disk contains a BASIC diagnostic test for your RAM expansion
module   and   several   demonstration  programs.  This  disk  is
provided  so  you  can  be  assured  that  your  device  operates
according to its design.

The  second  disk  is  a  CP/M  system disk that supports the RAM
expansion module. You may need to use this disk to boot CP/M when
you plan to use the RAM expansion module.  See Chapter 3,  How to
Use   the  RAM  Expansion  Module  in  CP/M  Mode,  for  complete
information about this disk.


1.4. SUGGESTIONS ON READING THIS GUIDE

Here is a brief description of what is contained in the remaining
chapters of this guide:

Chapter  2  --  INSTALLATION  AND  DEMONSTRATION  PROGRAMS  gives
illustrated  step-by-step  instructions  for  installing  the RAM
expansion  module  and  describes how to use the test program and
demonstrations provided.

Chapter  3  --  HOW  TO USE THE RAM EXPANSION MODULE IN CP/M MODE
contains  instructions on how to determine which CP/M system disk
you should use and explains how to use the RAM module with CP/M.

Chapter  4  --  HOW  TO USE THE RAM EXPANSION MODULE IN C128 MODE
describes the BASIC commands  SWAP,  STASH,  and  FETCH and shows
how  to  use  a memory map to keep track of information stored in
the RAM expansion module.

Chapter  5  --  TECHNICAL  SPECIFICATIONS;  this section provides
information for advanced users.

+---------------------------------------------------------------+
| Note:  It  is  important  to read and follow the installation |
| instructions in Chapter 2.  Even if you intend to use the RAM |
| expansion  module in  CP/M,  run the diagnostic test and demo |
| programs.                                                     |
+---------------------------------------------------------------+



2. INSTALLATION AND DEMONSTRATION PROGRAMS


2.1. INSTALLING THE RAM EXPANSION MODULE

1) Turn off your computer and any peripherals.

2) Carefully remove your RAM expansion module from its protective
   foam  packaging.  Locate  the  connector  on  the  edge of the
   device. See Figure 2-1.


                +------------------------------+
                |                              |
                |  C=      1750 RAM EXPANSION  |
                |                              |
                |==============================|
                |==============================|
                |==============================|
                |                              |
                |                              |
                |                              |
                |                              |
                |                              |
                |                              |
                |                              |
                ++-------------+---------------+
                 |             |
                 | [] [] [] [] | connector
                 |             | <--
                 +-------------+

              Figure 2-1, The RAM expansion module


3) Locate  the  expansion  port on the back of your C128 computer
   (see Figure 2-2).


   __/##_##_##_##___##_##_##_##___##_##_##_##___##_##_##_##\__
  |-----------------------------------------------------------|
  |  +----------+  ___  /-\ /-\         +-----+ +-----------+ |
  |  |==========| [___] \_/ \_/  []  () |\@@@/| |===========| |
  +-----------------------------------------------------------+
           ^
           |
  RAM module is inserted here

             Figure 2-2, C128 computer expansion port


4) Carefully  insert  the  connector  on the RAM expansion module
   into  the  expansion port on your computer.  Insert the module
   firmly  but  do  not  force  it,  as  this  might  damage  the
   connectors (see Figure 2-3.)


                       [ Picture Omitted ]

            Figure 2-3, RAM expansion module installed


5) Turn  on all your equipment.  Your RAM expansion module is now
   ready to use.


2.2. USING THE DEMONSTRATION PROGRAMS

Included  with  your RAM expansion module is a test/demonstration
disk. It contains a diagnostic program to test your RAM expansion
module  to  see if it is operating correctly,  and demonstrations
providing  an  example  of  how  you  might use the RAM expansion
module to aid your BASIC programming.

+---------------------------------------------------------------+
| Note:   A   40-column   monitor   is  necessary  to  run  the |
| demonstration  programs.  An  80-column monitor is sufficient |
| for the diagnostic test.                                      |
+---------------------------------------------------------------+


BOOTING THE DEMONSTRATION DISK

1) Turn off your computer.
2) Place the disk in the drive and close the disk drive door.
3) Turn  on the computer.  The message BOOTING STARTUP appears on
   the screen, and the program loads automatically.

   Note:  You can also load STARTUP by typing LOAD"STARTUP",8 and
   pressing (RETURN) or by typing BOOT (RETURN).

   STARTUP is a program that controls the demonstration programs.
   It  displays  a  menu  of  the  programs on the disk.  STARTUP
   reboots  automatically  when  the disk is in the drive and you
   press the reset button.


USING THE STARTUP MENU

The first program on the STARTUP menu is HELP.BAS. This is a file
that explains what the other programs on the disk do.

   To load HELP.BAS, choose option 1 from the STARTUP menu.

   A  series of information screens appears.  After you read each
   screen,  press  any  key  to continue.  When you have read the
   entire file, press the reset button. The disk will reboot, and
   you will be returned to the STARTUP menu.

The  second  program  on the STARTUP menu is RAMTEST. This is the
diagnostic test.

   To load RAMTEST, choose option 2 from the STARTUP menu.

   The program loads and this message appears:

       RAM EXPANSION TEST   SIZE = 128K (512K)
       TEST IS RUNNING WHEN UPPER LEFT
       LOCATION ON SCREEN IS FLICKERING.

   The  test  takes  about  five  minutes to run.  If an error is
   located, an error message appears and the test stops.

   If   no   error   is   located,  the  message  TEST  COMPLETED
   SUCCESSFULLY appears on the screen at the end of the test.

   Press the reset button, and the STARTUP program is rebooted so
   you can choose another program.

   IF  YOU  RECEIVE AN ERROR MESSAGE,  RESET THE COMPUTER AND RUN
   THE PROGRAM AGAIN. IF SEVERAL REPEATED EFFORTS TO RUN THE TEST
   FAIL,  TAKE  YOUR  RAM EXPANSION MODULE BACK TO THE DEALER WHO
   SOLD YOU THE MODULE.

The  rest of the programs on the disk are demonstration programs.
They  are  described  in the HELP file.  Choose the corresponding
number from the STARTUP menu to load each program.

Some  of the demonstration programs take several minutes to load,
but  begin automatically once loaded.  Some programs give you the
option of stopping  (using the RUN/STOP key)  then starting again
without  reloading the RAM expansion module. On screen directions
describe  the various options presented by each program. Pressing
the  reset  button  will always reboot the disk and return you to
the STARTUP menu.

Once you have run the RAMTEST and seen the demonstration programs
you should be confident your RAM expansion module works. Continue
with  Section 3, How To Use The RAM Expansion Module In CP/M Mode
or Section 4, How To Use The RAM Expansion Module in C128 Mode.



3. HOW TO USE THE RAM EXPANSION MODULE IN CP/M MODE


3.1. BOOTING CP/M

If  you  are  a CP/M user,  you are familiar with the CP/M system
disk packed with your C128 computer.  Another version of the CP/M
system  came  with your RAM expansion module.  The reason for two
CP/M  disks  is this:  early releases of the CP/M software packed
with the C128 computer do not support the RAM expansion module. A
special CP/M system disk, that supports the RAM expansion module,
was prepared and packaged with your RAM expansion module.

If  you  purchased  your  computer at the same time you purchased
your  RAM  expansion  module,  it  is  likely  that the CP/M disk
supplied with your computer supports the RAM expansion module.


     Commodore 128
    Personal Computer                     1700/1750 RAM
  _____________________                  Expansion Module
 |=====================|                   __________
 |~~~~~~~~~~~~~~~~~~~~~|                  | C=       |
 |_____________________|                  |==========|
 | #### #### #### #### |                  |~~~~~~~~~~|
 | ############## #### |                  |          |
 | ############## #### |                  |__________|
 |   ##########        |                  |____|
 `---------------------'
        _|  |_                               _|  |_
        \    /                               \    /
          \/                                   \/
      __________                           __________
     | CP/M 3.0 |                         | CP/M 3.0 |
     |    __    | May or may not          |    __    | Supports
     |   |  |   | support RAM             |   |  |   | RAM
     |    ~~    | expansion, depending    |    ~~    | expansion
     |    ||    | on release date         |    ||    |
      ~~~~~~~~~~                           ~~~~~~~~~~

                  FIGURE 3-1, CP/M system disks


If you purchased your C128 computer earlier, and later decided to
purchase a  RAM expansion module,  then you will probably need to
use the version of CP/M packed with your RAM expansion module.

To determine which is the most recent version of CP/M,  boot each
system  using the instructions below.  At the top of the screen a
title  and  date  appears.  Choose the most recent version of the
CP/M  system for use with the RAM expansion module, regardless of
which machine it was packaged with.

The CP/M system packaged with your RAM expansion module is booted
the  same  way as your original CP/M system was booted.  You have
two options:

1) Turn off the computer.  Place the disk in the drive, then turn
   on the computer. CP/M will boot automatically.
2) Start  in  C128 mode,  with equipment turned on.  Put the CP/M
   system  disk in the disk drive and type the BASIC command BOOT
   (RETURN).

Once the system is booted, CP/M will function in the usual manner
with  up to four external disk drives labeled A through D and the
virtual  drive  E.  Follow the instructions in your C128 Computer
System  Guide  for  using  CP/M without the RAM expansion module.
Provided  below  are  instructions  for  using  the RAM expansion
module like a fifth drive.


3.2. USING CP/M COMMANDS

Once  the system is loaded,  you can use the RAM expansion module
like a fast external drive simply by referring to drive M (Memory
drive).

For example,  to save time during a work session,  you might want
to  store  some  of the more commonly used transient utilities in
the RAM expansion module. Here is the method:

1) With the CP/M utility disk in the external drive A, type:

   A> PIP M:=A:FORMAT.COM [v] (RETURN)

   In  this  example,  the  PIP  utility would search the disk in
   drive A,  locate the FORMAT.COM file,  and store it in the RAM
   expansion module.  The [v] verifies that the transfer occurred
   correctly. You can also use DIR M: to determine what is stored
   in the RAM expansion module.

   Any filename could be used in place of FORMAT.  Be sure to use
   the correct filetype in addition to the filename if necessary.

2) When  the  computer  displays  the A> prompt,  the transfer is
   complete. Now the FORMAT utility is stored in the RAM disk.

3) To  compare  the speed of execution from an external drive and
   from the RAM expansion module:

   Type: A>FORMAT (RETURN)

   The  disk  drive  will  whirl  and eventually instructions for
   formatting  a  disk will appear on screen. Abort the format by
   pressing  (RETURN),  then  any  key,  then  answering N to the
   question, "DO YOU WANT TO FORMAT ANOTHER DISK?"

   Now load the FORMAT command from the RAM expansion module:

   Log on to drive M by typing M: at the A> prompt.

   Type: M>FORMAT (RETURN)

   Almost  instantly the format command is retrieved from the RAM
   expansion module and displayed on the screen. Alternately, you
   can  choose  to  execute the FORMAT command without logging to
   drive M> by typing M:FORMAT at the A> prompt.

This  example  should illustrate how the RAM expansion module can
speed up your operations. You can copy a number of files into the
RAM  expansion module with a series of PIP commands.  Or copy the
entire contents of a disk:

   A>PIP M:=A:*.*     will copy all the files from the disk in
                      drive A into the RAM expansion module.

Note  that  a full single-sided disk holds 160K of data.  If your
disk  is  completely  full,  the entire contents cannot be copied
into the 1700 RAM Expansion Module.

Once the RAM expansion module has been loaded with a program, use
of  the  program  is  no different than if the program were in an
external  drive.  If  you  are  saving  data files for later use,
however,  you  may want to save them on an external drive instead
of in the RAM expansion module.

Using  the  reset  button does not clear the expansion RAM banks,
only the C128 computer's main memory.

To avoid accidental loss of your work, periodically save programs
or  data  files  in  progress  on  disk,  as  well  as in the RAM
expansion  module.  A  power  surge,  or  an  accidentally pulled
electric cord,  can have a devastating effect on your work if you
only store it in the RAM expansion module.



4. HOW TO USE THE RAM EXPANSION MODULE IN C128 MODE


4.1. BASIC COMMANDS

There  are  three  BASIC  commands built into BASIC 7.0 that were
designed  especially for use with the RAM expansion module. These
commands  handle  the three types of data transfers possible with
the RAM expansion module:

1) STASH - Stores data in the RAM expansion module

2) FETCH - Retrieves data stored in the RAM expansion module  and
           places them in main memory

3) SWAP  - Exchanges data stored in the RAM expansion module with
           data stored in main memory

Each  of  these command words is followed by four parameters that
define  how large a block of data is being transferred,  where in
main  memory  the  data  is  currently  stored,  where in the RAM
expansion   module   (i.e.  what  address)  the  data  should  be
transferred, and what expansion RAM bank is being used.

The parameters are the same for all three commands:

FETCH
STASH      number of bytes,intsa,expsa,expba
SWAP

where bytes = number of bytes involved in the transfer
      intsa = starting address of host RAM (0 - 65535)
      expsa = starting address of expansion RAM (0 - 65535)
      expba = expansion RAM bank number (0 - 1 on the 1700)
                                        (0 - 7 on the 1750)

Note: FETCH, STASH, and SWAP only accept decimal numbers.

When  you use any of these commands,  you are transferring blocks
of data from one area of RAM to another. It is important that you
know what you are transferring,  and where you are putting it. If
you  transfer  data  into  an  area that already is occupied by a
program or other data,  the data you transfer into that area will
overwrite the original data. This can have an undesired effect on
the outcome of the transfer.


4.2. MEMORY LOCATIONS

In  order  to guarantee a safe transfer,  you need to be aware of
the memory map for your computer. It is a diagram, see Figure 4-1
on  next  page,  that  shows what each section of your computer's
memory   stores.   Certain  areas  are  set  aside  for  specific
functions, and other areas are free for your programs. The entire
contents  of  the RAM expansion module is up to you;  no space is
preallocated.

When you perform any operation with your computer, data is stored
in  your  computer's  memory.  Each  memory  location is given an
address which,  like the street addresses of houses,  can be used
to  identify  a  particular  location.  The  specific contents of
memory  locations  determines  the output  of programs,  what the
screen looks like, and other computer functions.

The  addresses  of  memory locations accessible by the user range
from 0 to 65535.  Many of these locations,  however, have special
purposes.  For  example  the  addresses between 4608 and 4864 are
reserved for storing absolute values for BASIC programs.

One important note:  the BASIC commands STASH, FETCH and SWAP can
only  be  used to transfer or retrieve data in Bank 0 of the C128
computer's internal RAM. See the section entitled NOTES FOR BASIC
PROGRAMMERS in Chapter 5 for details on accessing Bank 1.

The  1700  RAM  expansion module contains two RAM banks labeled 0
and 1.  The 1750 RAM expansion module has eight RAM banks labeled
0 to 7.  All the banks in the RAM expansion modules are available
with the BASIC commands STASH, FETCH, and SWAP. The RAM expansion
module banks bear no relation to the C128 computer RAM banks.


    C128 RAM     Decimal  Hex     C128 ROM
+---------------+ 65535  FFFF +-------------+ - Kernal Jump Table & -.
| NMI RST IRQ   |             |             |   Hardware Vectors     |
| CP/M RAM Code | 65357  FF4D |             |                        |
|Kernal RAM Code|             |             |                        |
|               |             |             |                        |
|               |             |             |                        |
+---------------+ 65285  FF05 +-------------+ - Kernal Interrupt     |
| MMU           |             |/////////////|   Dispatch Code        |
| Configuration |             |/////////////|                        |
| Register      |             |/////////////|                        |
+---------------+ 65280  FF00 +/////////////+ - MMU Configuration    |
|               |             |             |   Registers            |
|               |             |             |                        |
|               |             |             |                        |
|               | 64640  FC80 +-------------+ - ROM reserved for     |~~\ HIGH
|               |             |             |   Foreign Lang.Versions|__/ ROM
|               |             |             |                        |
|               |             |             |                        |
|               | 64128  FA80 +-------------+ - Editor Tables        |
|               |             |             |                        |
|               |             |             |                        |
|               |             |             |                        |
|               | 57344  E000 +-------------+ - Kernal ROM Code      |
|BASIC TEXT AREA|             |/////////////|                        |
| (Basic text   |             |/////////////|                        |
|begins at $1C00|             |/////////////|                        |
|  if bit-map   | 53248  D000 +/////////////+ - I/O Space            |
|  unallocated  |             |             |                        |
|               |             |             |                        |
|               |             |             |                        |
|               | 49152  C000 +-------------+ - - Editor ROM Code - -|
|               |             |             |                        |
|               |             |             |                        |
|               | 45056  B000 +-------------+ -- Monitor ROM Code - -|
|               |             |             |                        |~~\ MID
|               |             |             |                        |__/ ROM
|               | 32768  8000 |             | - - - - - - - - - - - -|
|               |             |             |                        |
|               |             |             |                        |
|               |             |             |                        |
|               |             |             |                        |
|               |             |             |                        |~~\ LOW
|               |             |             |                        |__/ ROM
+---------------+ 16384  4000 +-------------+ - - Basic ROM Code - --~
|  VIC BIT-MAP  |
|    Screen     |
+- - - - - - - -+ 8192   2000
|  VIC BIT-MAP  |
| Color (VM#2)  |
+---------------+ 7168   1C00
| Reserved for  | 6912   1B00
| Applications  | 6656   1A00
|               | 6400   1900
+---------------+ 6144   1800
| Reserved for  |
| Applications  |
|               |
+---------------+ 5120   1400
| Reserved for  |
| Applications  |
+---------------+ 4864   1300
|     Basic     |
|    Absolute   |
|   Variables   |
+---------------+ 4608   1200
|     Basic     |
|    DOS/VSP    |
|   Variables   |
+---------------+ 4360   1108
|   CP/M Reset  |
|      Code     |
+---------------+ 4352   1100
|   Function    |
|     Key       |
|    Buffer     |
+---------------+ 4096   1000
|    Sprite     |
|  Definition   | 3840   0F00
|     Area      |
+---------------+ 3584   0E00
|    RS-232     |
|    Output     |
|    Buffer     |
+---------------+ 3328   0D00
|    RS-232     |
|    Input      |
|    Buffer     |
+---------------+ 3072   0C00
| Disk Boot Page|
|- - - - - - - -| 3008   0BC0
|Cassette Buffer|
+---------------+ 2816   0B00
| Monitor&Kernal|
|   Absolute    |
|   Variables   |
+---------------+ 2560   0A00
|     Basic     |
|   Run-Time    | 2304   0900
|     Stack     |
+---------------+ 2048   0800
|      VIC      |
|     Text      |
|    Screen     |
|    (VM #1)    |
+---------------+ 1024   0400
| Basic RAM Code|
|- - - - - - - -| 896    0380
| Kernal Tables |
|- - - - - - - -| 828    033C
|   Indirects   |
+---------------+ 764    02FC
|Kernal RAM Code|
|- - - - - - - -| 674    02A2
|Basic & Monitor|
|  Input Buffer |
+---------------+ 512    0200
|  System Stack |
|- - - - - - - -| 329    0149
|Basic DOS Using|
|- - - - - - - -| 272    0110
|   F BUFFER    |
+---------------+ 256    0100
|   Kernal ZP   |
|- - - - - - - -| 144    0090
|   Basic ZP    |
|- - - - - - - -| 2      0002
+---------------+ 0      0000

                     FIGURE 4-1, C128 computer memory map


4.3. BASIC EXAMPLES

Let's create a program that accesses the RAM expansion module.

1) Reset your computer in 40 column mode  so the start-up message
   is visible. The screen should display:

             COMMODORE BASIC V7.0 122355 BYTES FREE
              (C) 1985 COMMODORE ELECTRONICS, LTD.
                    (C) 1977 MICROSOFT CORP.
                       ALL RIGHTS RESERVED

2) Move the cursor up to the start-up message. Type some changes:
   perhaps replace the number of bytes free,  or put your name in
   place of Commodore.  Make all your changes with the cursor and
   INST/DEL keys; be sure not to press (RETURN).
3) When  you  are satisfied with the changes,  move the cursor to
   the bottom line of the screen.

   Type: STASH 1000,1024,0,0 (RETURN)

   This  command  stores  1000  bytes  from  the  computer's main
   memory, beginning at address 1024 in the RAM expansion module.
   Address 1024 marks the beginning of the text screen,  the part
   of memory where the current screen contents are stored.

4) PRESS:  (SHIFT) and (CLR/HOME) to clear the screen.  Type this
   program:

   10 FOR X = 1 TO 25
   20 FETCH 1000,1024,0,0
   30 SLEEP 1
   40 PRINT"(SHIFT) and (CLR/HOME)"
   50 PRINT X: SLEEP 1: NEXT X

5) Type RUN (RETURN). The altered startup message is fetched from
   the  RAM expansion module,  displayed,  then a counter flashes
   and the image is fetched again.

This example gives you a starting point for more creative uses of
the RAM expansion.  Let's try a simplified version of the graphic
demos  included  on  the  demonstration disk packed with your RAM
expansion module.

Turn  the  machine  off  and  then  on to clear the RAM expansion
module's memory.  Note that using the reset button does NOT clear
the expansion RAM banks, only the C128 computer's main memory.

1) Clear the screen using (SHIFT) and (CLR/HOME).
2) Create a picture using graphic characters. Try a smiling face,
   or other simple design.
3) Cursor down to the bottom of the screen.

   TYPE: STASH 1000,1024,0,0 (RETURN)

4) When the computer responds READY, clear the screen.

   TYPE: FETCH 1000,1024,0,0 (RETURN)

   Your  smiling face returns. Move the cursor up to the picture,
   and alter it in some way. Perhaps change the smile to a frown,
   or add eyebrows.  Delete any unnecessary characters (such as a
   READY  message)  by using the spacebar to go over them.  Don't
   use  the  (INST/DEL) key as this can change the arrangement of
   your  picture.  Be  careful  to  align the picture in the same
   location  it originally was.  Use the spacebar to add lines of
   space  and  move  the  picture  up  or down a row at a time if
   necessary.

6) Move the cursor to the bottom of the screen.

   TYPE: STASH 1000,1024,1000,0 (RETURN)

   Notice  that  the starting address given for the RAM expansion
   module is 1000,  not 0 as in previous trials.  This is because
   we  don't  want  to  overwrite  the  existing  screen with the
   smiling face.

7) Clear the screen once again, and type this program:

   10 FOR X = 1 TO 10
   20 FETCH 1000,1024,0,0: REM SMILE FACE
   30 SLEEP 1
   40 FETCH 1000,1024,1000,0: REM FROWN FACE
   50 SLEEP 1
   60 NEXT X

8) Type (RUN) to view the program.

These  examples  make  use of an area of RAM in the C128 computer
that  is  easy to access.  Since the text screen always begins at
address  1024,  and  is  exactly  1000 bytes long,  we can safely
create as many text screens as we like. Each screen can be stored
in the RAM expansion module,  in addresses 1000 bytes apart,  and
later fetched without any problem.

Storing  other  types of data,  such as programs,  requires being
able  to  use machine language to view other addresses.  Detailed
information  about  machine  language  and  the  machine language
monitor is contained in the C128 PERSONAL COMPUTER SYSTEM GUIDE.



5. TECHNICAL SPECIFICATIONS


It  is  possible  to  use  the  RAM  expansion module in the ways
described  in chapters 3 and 4 of this manual without being aware
of  the RAM Expansion Controller (REC).  The REC is the processor
inside  the RAM expansion module that makes communication between
the  C128  computer  and the RAM expansion module possible.  Both
CP/M  and  the  built-in BASIC commands automatically control the
transfer  of  information.  In order to gain more precise control
over the RAM expansion module, details about the REC are needed.


5.1. OPERATING MODES

The REC has four primary operating modes. These are:

1) Transfer a block of data  from main memory to expansion memory
   (BASIC command: STASH)

2) Transfer a block of data  from expansion memory to main memory
   (BASIC command: FETCH)

3) Exchange a block of main memory  with  a  block  of  expansion
   memory (BASIC command: SWAP)

4) Verify a block of main memory with a block of expansion memory

The  REC  has several internal registers which can be used to set
up a particular operating mode.  Modes can be selected by setting
the  appropriate  bits in the command register  (see Figure 5-1).
The starting C128 address,  expansion RAM address,  expansion RAM
bank, and number of bytes are all programmable values.


                          REC Register Description
+-------+-----+-------------------------------------------------------------+
|ADDRESS|BITS |                          FUNCTION                           |
+-------+-----+-------------------------------------------------------------+
|  $00  | 7-0 | Status Register -- Read Only                                |
|       |     | 7 - Interrupt Pending; 1 = Interrupt waiting to be serviced |
|       |     | 6 - End of Block;      1 = Transfer complete                |
|       |     | 5 - Fault;             1 = Block verify error               |
|       |     | 4 - Size;              0 = Total expansion = 128K           |
|       |     |                        1 = Total expansion = 512K           |
|       |     | 3-0 - Version;                                              |
|       |     | Note: Bits 7-5 are cleared when this register is read       |
+-------+-----+-------------------------------------------------------------+
|  $01  | 7-0 | Command Register -- Read/Write                              |
|       |     | 7 - Execute;           1 = Transfer per current config.     |
|       |     | 6 - Reserved;                                               |
|       |     | 5 - Load;              1 = Enable AUTOLOAD option           |
|       |     | 4 - FF00;              1 = Disable FF00 decode              |
|       |     | 3 - Reserved;                                               |
|       |     | 2 - Reserved;                                               |
|       |     | 1,0 - Transfer type;   00 = transfer C128 --> RAM module    |
|       |     |                        01 = transfer C128 <-- RAM module    |
|       |     |                        10 = swap C128 <--> RAM module       |
|       |     |                        11 = verify C128 -- RAM module       |
+-------+-----+-------------------------------------------------------------+
|  $02  | 7-0 | C128 Base Address, LSB -- Read/Write                        |
|       |     |   Lower 8 bits of base address, C128                        |
+-------+-----+-------------------------------------------------------------+
|  $03  | 7-0 | C128 Base Address, MSB -- Read/Write                        |
|       |     |   Upper 8 bits of base address, C128                        |
+-------+-----+-------------------------------------------------------------+
|  $04  | 7-0 | Expansion RAM address, LSB -- Read/Write                    |
|       |     |   Lower 8 bits of base address, expansion RAM               |
+-------+-----+-------------------------------------------------------------+
|  $05  | 7-0 | Expansion RAM address, MSB -- Read/Write                    |
|       |     |   Upper 8 bits of base address, expansion RAM               |
+-------+-----+-------------------------------------------------------------+
|  $06  | 2-0 | Expansion RAM bank -- Read/Write                            |
|       |     |   Expansion RAM bank pointer.                               |
|       |     |   Bits 2 (MSB) to 0 (LSB) are significant                   |
+-------+-----+-------------------------------------------------------------+
|  $07  | 7-0 | Transfer length, LSB -- Read/Write                          |
|       |     |   Lower 8 bits of the byte counter                          |
+-------+-----+-------------------------------------------------------------+
|  $08  | 7-0 | Transfer length, MSB -- Read/Write                          |
|       |     |   Upper 8 bits of the byte counter                          |
+-------+-----+-------------------------------------------------------------+
|  $09  | 7-5 | Interrupt mask register -- Read/Write                       |
|       |     | 7 - Interrupt enable          1 = Interrupts enabled        |
|       |     | 6 - End of Block mask         1 = Interrupt on end of block |
|       |     | 5 - Verify error              1 = Interrupt on verify error |
+-------+-----+-------------------------------------------------------------+
|  $0A  | 7-6 | Address control register -- Read/Write                      |
|       |     | 0,0 = Increment both addresses (default)                    |
|       |     | 0,1 = Fix expansion address                                 |
|       |     | 1,0 = Fix C128 address                                      |
|       |     | 1,1 = Fix both addresses                                    |
+-------+-----+-------------------------------------------------------------+

                                 Figure 5-1


Note:  The  Base  address of the REC registers in the C128 memory
map is DF00 in I/O space.  The addresses of the REC registers can
be  obtained  by adding the value in the Address column in Figure
5-1 to the base address of DF00.


5.2. DIRECT MEMORY ACCESS OPERATION

Direct  Memory  Access  (DMA)  is  the  process  the  REC uses to
transfer data to and from the C128 computer's memory.  During DMA
the  C128 computer processor is temporarily halted so the REC may
access the C128 computer's memory.

There  are  two  different  events which cause the REC to begin a
transfer sequence.

1) If  the FF00 option in the command register ($01) is disabled,
   the  DMA  begins  right  after  the  execute bit is set in the
   command register.

2) If the  FF00  option in enabled,  the DMA begins right after a
   write to address FF00 is detected -- providing the execute bit
   was set in the command register.

The  purpose of the FF00 option is to allow the REC to access the
RAM  beneath  I/O space.  The REC registers are I/O mapped on the
C128 expansion bus which means that, without the FF00 option, I/O
space  would be enabled when the DMA was initiated.  Address FF00
is the configuration register within the C128's MMU. This option,
therefore,  allows  the  user  to  reconfigure  the C128's memory
before the DMA takes place.  The FF00 option is cleared each time
it is used.


5.3. SPECIAL FEATURES

AUTOLOAD  --  One  special  feature  is AUTOLOAD.  Selecting this
option  in  the  command  register automatically reloads the C128
base   address   registers,  the  external  memory  base  address
registers,  the  external  memory  bank,  and  the  byte  counter
registers at the end of the transfer.

This  is  useful if one operation is to be executed repeatedly on
one  particular  block  of  data.  Note  that in verify mode,  if
AUTOLOAD is selected, the address where the verify error occurred
is  lost.  Ordinarily upon finding a verify error,  the REC halts
the  DMA  cycle  and both address registers and the bank register
point to one location above the address that failed.

ADDRESS  CONTROL  --  Another  special  feature of the REC is the
ability  to hold a source and/or destination address fixed in any
mode. This is accomplished by setting the appropriate bits in the
address  control  register  ($0A).  The default is that addresses
will increment  for both source and destination.  It is possible,
with  a fixed C128 address,  to DMA to any C128 I/O device except
the 8563.

INTERRUPTS  --  An  interrupt can be generated on an end of block
condition  or  verify error by enabling interrupts and by setting
the corresponding mask bits in the interrupt mask register ($09).
In  either  case,  the  corresponding  flag  is set in the status
register.  Interrupt  flags  are  cleared upon reading the status
register.  The  interrupt  mask  register  bits stay as they were
before  the interrupt/clear sequence.  For proper operation,  the
status  register ($00) must be read at least once before a DMA is
initiated  with interrupts enabled.  It is important to clear out
the  previous  status  before  any  mode  is  used with interrupt
option.


5.4. OPERATION DESCRIPTION

If  a  specified  address  range exceeds the address range in the
selected  expansion  RAM bank,  a "wrap" will occur into the next
bank.  This  will  happen whenever the given byte counter exceeds
the  number  of  bytes left in the selected bank. If the selected
bank   is   equal   to   the  maximum  for  a  particular  memory
configuration,  then  the  wrap is to bank 0.  This will give the
appearance  of  contiguous memory.  The C128 side always wraps to
the beginning of the same bank.

Under  normal  operation (no AUTOLOAD, addresses increment), both
address  registers  will  point  to  the  next  sequential memory
location  outside  the  selected transfer range at the end of the
transfer.  This  is  true  for  any mode and applies to both base
address pointers except one that is held fixed.  The bank pointer
will  also  be  updated  if necessary at the end of the transfer.
Also   note   that  under  normal  operation,  the  byte  counter
decrements to the value 1.  Care should be taken,  therefore,  to
check  the  transfer  complete bit in the status register and not
rely  on  the  byte  counter value to indicate an end of transfer
condition.  A byte counter of 0 results in a transfer of  a  full
64K bytes. Again, wrapping occurs in all modes of operation.

Important operating notes

1) The Z80 must not be in control when a DMA is requested.

2) The REC cannot reconfigure the MMU during a DMA cycle.

3) On the C128 the DMA bank is set by the VIC bank pointer in the
   MMU, not the processor bank pointer.

4) The  C128  computer  must  be  in  1 MHz  mode  when  a DMA is
   requested.


5.5. TIMING

The  effective  transfer  rate is 1 Mbyte/sec for uni-directional
transfers   via   STASH   and   FETCH,  and  500  Kbytes/sec  for
bi-directional  transfers  accomplished with SWAP.  This transfer
rate  does  not  include  VIC DMA time.  The VIC chip has highest
priority on the C128 computer unless it is disabled, so VIC DMA's
take precedence over REC DMA's.


5.6. BANK CONFIGURATION

Bank  Select  (BS)  is  provided  as  a  means of configuring the
controller so it can direct RAS and CAS to the appropriate bank.

     +------+----------------+----------------+------------+
     |  BS  |     Bank I     |    Bank II     |   Total    |
     +------+----------------+----------------+------------+
     |   0  |     64K x 1    |     64K x 1    |    128K    |
     |   1  |    256K x 1    |    256K x 1    |    512K    |
     +------+----------------+----------------+------------+

This bit in the status register reflects the state of an external
jumper which was preinstalled in the factory.


5.6. NOTES FOR BASIC PROGRAMMERS

The  BASIC  commands  STASH,  FETCH, and SWAP can only be used to
transfer  and  retrieve  data  in  Bank  0 of the C128 computer's
internal  RAM.  To  access  Bank  1  of  the  C128 computer it is
necessary  to alter a special control register on the C128.  This
register  is the RAM control register in the MMU,  address $D506.
Bits  6  and  7  of  this  register control both the VIC RAM bank
pointer and the C128 DMA bank pointer.

          +---------+----------+----------------------+
          | Address |   Bits   |       Function       |
          +---------+----------+----------------------+
          |  $D506  |    6-7   |   00   C128 Bank 0   |
          |         |          |   10   C128 Bank 1   |
          +---------+----------+----------------------+

Be  sure  to  restore these bits to their original values or your
40-column screen will contain the wrong information.

Note  that I/O is enabled for the three BASIC commands in Version
0  of  the  C128  kernal ROM.  In Version 1 of the ROM I/O can be
disabled  by  using  the  BANK  command.  See  the  C128 Personal
Computer System Guide for details on the BANK command.

The  kernal  ROM  version  can  be determined by PEEKing location
$FF80. Version 0 contains a 0 while Version 1 contains a 1.

*********

End of Project 64 etext 1700/1750 RAM Expansion Module User's Guide.

*********
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