dk'tronics DKT64k User manual

Dk'tronics 64K/256K Memory Expansion
For the Amstrad CPC comp ters

64K AND 256K MEMORY EXPANSION UNITS.
1.0 PREFACE 1
1.1 INSTALLATION 2
1.2 USING YOUR EXTRA RAM 2
1.3 RAM TEST 3
1.4
EXTENDED BASIC COMMANDS
3
1.5 WINDOWS AND PULLDOWN MENUS 4
1.5.1 MORE WINDOWING 5
1.6 ARRAYS, VARIABLES AND STRINGS 6
1.6.1 MORE ABOUT ARRAYS 9
1.6.2 STRING STORAGE 10
1.7
ANIMATION AND PICTURE SHOWS
11
1.8 ADVANCED PROGRAMMING 13
1.9
PEEKING AND POKING
15
1.10 PROGRAMMING WITHOUT RSX's 16
1.11 TECHNICAL DETAILS 17
1.11.1 THE LOAD ADDRESS 17
1.11.2
SAVING TO DISC
17
1.11.3 INCREASING CP/M 2.2 TPA 17
1.11.4 COMMERCIAL PROGRAM COMPATIBILITY 17
1.11.5 USING CP/M 2.2 18
1.12 ERROR MESSAGES 18
1.13 REFERENCE OF RSX COMMANDS 19
1.14 TECHNICAL DETAILS (HARDWARE) 20
1.15 CUSTOMIZING YOUR CP/M+ DISC 22
CONTENTS
PAGE.

64K and 256K MEMORY EXPANSIONS.
These nits are available for the CPC 464, 664 and 6128 comp ters.
By sing the 64K pgrade the 464 and 664 comp ters will have the same amo nt
and config ration of RAM as the CPC 6128. The 256K gives an extra 192K on top
of this! The expansion will allow the se of CP/M+ as s pplied with the CPC
6128 with its massive 61K TPA opening p an even larger software base for
Amstrad sers. There is also an tility for increasing the TPA on CP/M 2.2 to
61K.
The RAM can be accessed by means of bank switching sing a single I/0 port.
Memory is act ally switched in and o t of the 64K Z80 address space in 16K
s b-blocks, as are the ROMs. The port determines which partic lar combination
of the original fo r 16K s b-blocks and any new s b-blocks from the expansion
RAM will occ py the 64K address space at any time. Control of the I/0 port
can be from either BASIC or machine code.
To se the additional 64K/256K of RAM, the expansion is s pplied with bank
switching software (altho gh it can be switched witho t this software).
The software adds some extra BASIC commands, RSXs, which make it possible to
se the second 64K (or 3rd, 4th and 5th in the case of the 256K expansion)
for storage for screens, windows, graphics and BASIC arrays. This ability
means that yo can write m ch larger BASIC programs, as most of the memory on
the nexpanded CPC464/664 is normally sed for arrays, variables and
graphics.
The additional BASIC commands are :
|BANK,n Map a bank of 16K directly into memory space.
|SWAP Alternate between the low an high screens.
|LOW Change to the low screen.
|HIGH Change to the high screen. (Defa lt screen).
|SAVES,n Store a screen to a 16K bank.
|LOADS,n Retrieve a screen from a 16K bank.
|SAVEW,w,n Store a window's contents into expansion RAM.
|LOADW,w,n Load a window with data from the expansion RAM.
|SAVED,n,s,l Transfer original RAM to expansion RAM.
|LOADD,n,s,l Load original RAM from expansion RAM.
|PEEK,n,s,v Read the val e of a byte in expansion RAM.
|POKE,n,s,v Change a byte in the expansion RAM.
These commands make s ch feat res as p ll down men s, f ll screen animation
and large spreadsheet type programs or databases very easily programmed from
BASIC as never before possible on the nexpanded CPC464 and 664 comp ters.
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WARNING.
Ens re that the power to yo r Amstrad comp ter is switched OFF before yo fit
the interface to the expansion socket. Fail re to comply with these
instr ctions may ca se permanent damage to the RAM pack or the comp ter.
1.1 Installation.
Power down yo r Amstrad comp ter. Pl g the RAM pack into the socket on the
back of the comp ter. On the CPC 464 this socket is labelled 'Floppy
Disc', on the CPC 664 and CPC 6128 the socket is labelled 'Expansion'.
Other expansions s ch as the Amstrad Disc interface for the CPC 464,
DK'tronics Lightpen and Speech Synthesizer, or ROM expansions can be
fitted into the expansion socket on the back of the RAM pack. Now switch on
the comp ter.
The comp ter sho ld power p as normal. If it fails to do so, check that
all the connections are correctly made. Note that all DK'tronics prod cts
have a key location on the connector to ens re that there can be no
alignment problems. OTHER interfaces may not have this keyway (the
Amstrad disc interface is the most familiar example). Hence any
connection problems will s ally lie between the RAM pack and these
expansions. If this is the case, try reconnecting the interfaces BEFORE
inserting the RAM pack into the comp ter. This will give yo a better view
when lining p the pins.
If the comp ter fails to power p, or crashes on power p (Miscellaneo s
patterns all over the screen!), the monitor may c t o t the power to
the comp ter. On the colo r monitor, j st switch the MONITOR off and
then attempt to reconnect as above. The monochrome monitor may have to
remain switched off for several seconds before power will be reinstated
to the comp ter.
It is very nlikely that the comp ter will fail to power p with the RAM
pack alone. If this is the case, then the fa lt will probably lie with the
RAM pack. * Ret rn the RAM pack to RAM ELECTRONICS if this is the case.
* IT IS ESSENTIAL THAT YOU COMPLETE YOUR WARRANTY REGISTRATION CARD AND
RETURN IT TO US IMMEDIATELY UPON PURCHASING THIS PRODUCT FROM YOUR DEALER
(UK ONLY).
1.2 USING YOUR EXTRA RAM.
There are two ways to se the extra RAM. There is a cassette s pplied with
the RAM pack containing extensions to BASIC. Here the extra RAM can be
sed simply from BASIC programs. Alternatively, the RAM is accessible both
from BASIC and machine code sing the OUT command. The experienced
programmer will be able to se the RAM for whatever he pleases and
write c stom software for that p rpose. Commercial programs will no
do bt se this approach.
The second method is described in detail in section 1.10. The first way
is explained in the following chapters:-
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With the comp ter set p as above, load the RSX software from the cassette
tape s pplied:-
On disc systems type '|TAPE' and press <ENTER>
b) Type 'RUN”' and press <ENTER>.
c) The loading seq ence is described in detail in yo r Amstrad ser
man al.
d) When the program has finished loading, yo will be asked to enter a
loading address. J st press <ENTER> for now. (See section 11.)
e) The comp ter will test the RAM and then print o t how m ch RAM yo have
got, then the comp ter memory will be clear ready for yo r own programs.
1.3 RAM TEST.
When the RSX code is first loaded, it does an extensive RAM test.
Sho ld the RAM not f nction correctly the program will inform yo that an
error has been fo nd. Along with this, it will print o t diagnostic
information to help in the repair of the RAM pack.
In the nlikely event that an error is fo nd, please note the information that
is given and ret rn the RAM pack for replacement or repair.
(See warranty registration note.)
1.4 EXTENDED BASIC COMMANDS.
There are a total of twelve extra commands provided by the RSXs on
tape. Some may have parameters, some will not. Sometimes the command may
have different formats and n mbers of parameters. We have tried to disc ss
each command in its simplest form and later sections will describe added
parameters which make the command more flexible and economic on memory.
Yo may have noticed that d ring the RAM test, the comp ter printed o t the
n mber of the 'bank' it was testing. Each bank is 16K of memory. For
the 64K expansion there are 4 banks while the 256K RAM pack has 16
banks. To access a partic lar part of the expansion's m emory the re h as
to be a bank n mber and possibly a bank address.
For example, type:- '|SAVES,1' and press <ENTER>
The comp ter will respond with READY. What yo have done is to store what
was on the screen into bank 1.
Now clear the screen sing CLS. To get the screen's contents back,
type:- '|LOADS,1' and press <ENTER>
Yo can save as many screens as yo have memory for. That means fo r
screens on the 64K RAM and sixteen screens for the 256K RAM. Screen displays
co ld be created from another program or drawn sing a lightpen. Store these
on tape or disc then load them back into RAM for se thro gho t the program.
Screen displays which take a long time to create within a program, for
example mazes, can be created once, then stored for instant se whenever
necessary.
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The command can be s mmarized:-
|SAVES,[n] save data to bank (n= the bank n mber)
|LOADS,[n] load data from bank
1.5 WINDOWS AND PULLDOWN MENUS.
One of the feat res that makes the Amstrad's windows less flexible than
those on larger b siness machines, is the fact that the contents of a
window which overlaps another are lost when the other window is sed.
There are two new commands which allow the contents of windows to be saved
and reloaded from RAM. This will allow the se of tr e p lldown men s,
that can cover text, b t not remove it.
EXAMPLE:-
NEW
10 MODE 1
20 FOR i=0.05 TO 1 STEP 0.05 : REM Draw grid on screen
30 MOVE 640*i,0 : DRAW 640*i,400
40 MOVE 0,400*i : DRAW 640,400*i
50 NEXT i
60 WHILE INKEY$="" : WEND : REM Wait for a key press
70 WINDOW#1, INT(RND(1)*19+1),INT(RND(0)*9+INT(RND(1)*5+17)),
INT(RND(1)*14+1),INT(RND(0)*14+INT(RND(1)*10+5))
80 PEN#1, 2 : PAPER#1, 3
90 |SAVEW,1,1 : REM Save contents of window into RAM
100 CLS#1 : REM Clear window
110 WHILE INKEY$="" : REM Wait for 2nd key press
120 PRINT#l, "This is a window"
130 WEND
140 |LOADW,1,1 : REM restore window's contents
150 GOTO 60
The above program ses two new commands: |LOADW and |SAVEW. As yo are
probably aware, there are eight windows (0-7) which can be defined. The
first parameter is the reference to a window. The second is the bank
n mber.
|SAVEW, [window n mber], (bank] save window to bank
|LOADW, (window n mber], (bank] load window from bank
See the chapters in the ser man al abo t windows for more details.
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1.5.1 MORE WINDOWING.
A window of any size, even the whole screen, will fit into a single bank
of expansion RAM. This is fine if yo r window is nearly a f ll screen or
will vary in size like the above example. On the other hand if yo r window
was defined as 10 x 10 in Mode 1, then the amo nt of memory needed to
store this window wo ld be less than 16K. In fact only 1600 bytes are
needed (see below). Th s to se a whole bank wo ld mean wasting over 14K of
memory.
To deal with this problem, the RSX window command can take an extra
parameter to define where yo want the window's contents to reside in the
RAM bank. In the 10 x 10 window yo co ld place the data anywhere
between 0 and 14783.
The command can be written:-
|SAVEW, [window n mber], [bank], [bank address]
|LOADW, [window n mber], [bank], [bank address]
The bank address is an address between 0 and 16383. The amo nt of data in
bytes sed to store a window needs to be taken away from the top val e
and this leaves the range between which the data can be stored. If
yo p t the data at the bottom of the RAM bank, at address 0, then the
memory from 1600 to 16383 is free for other windows or data arrays.
HOW TO CALCULATE A WINDOW'S SIZE.
In order to have more than one window per bank, yo need to know how m ch
memory the window will take p. If the window will vary in size between
two limits, se the higher of the two. Depending on which mode yo are
sing, the fig res are calc lated as below.
In each case: X1 is the left most x coordinate
X2 is the right most x coordinate
Y1 is the top y coordinate
Y2 is the bottom y coordinate
MODE 0 SIZE=(X2-X1+1) * 4 * (Y2-Y1+1) * 8
MODE 1 SIZE=(X2-X1+1) * 2 * (Y2-Y1+1) * 8
MODE 2 SIZE=(X2-X1+1) * (Y2-Y1+1) * 8
The comp ter will give an error if the window is too large to fit in the
space yo have allotted for it. Also if the size is miscalc lated the
windows may overlap in the bank and ca se strange effects.
EXAMPLE 2:-
10 PEN 1 : PAPER 0 : MODE 1
20 size = 14 * 2 * 10 * 8
30 LOCATE 1, 13 : PRINT " 'n' for new window 'd' to remove window"
40 WINDOW 1, 14, 1, 10 : PAPER 3 : CLS
50 bankaddress=0 : level=0
60 PRINT#level, "Window";level
70 keypress$=LOWER$(INKEY$)
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80 IF keypress$="n" THEN GOSUB 110
90 IF keypress$="d" THEN GOSUB 190
100 GOTO 60
110 If level=7 THEN RETURN
120 level=level+1
130 WINDOW#level, 1+level*3, 14+level*3, 1+level*2, 10+level*2
140 |SAVEW,level,1,bankaddress
150 bankaddress=bankaddress+size
160 PEN#level,0 : PAPER#level, (level AND 1) + 1
170 CLS#level
180 RETURN
190 IF level=0 THEN RETURN
200 bankaddress=bankaddress – size
210 |LOADW,level,1,bankaddress
220 level=level-1
230 RETURN
The above program only ses one bank of RAM b t all 8 windows are
defined. The variable 'level' is sed to stand for the level of
windows and the variable 'bankaddress' points to the next free place in
the bank RAM.
1.6 ARRAYS, VARIABLES AND STRINGS.
There are two general p rpose data moving commands to allow data from
the program to be moved to and from the RAM pack.
These two commands are :
|SAVED, [bank], [Start location], [length], [bank address]
|LOADD, [bank], [Start location], [length], [bank address]
The first parameter references which bank yo want to se. The start
location is a memory address where there is some data. The amo nt of data
is given as the length. Optionally a bank address can be given to allow
more than one type of data to be stored in the RAM.
It is possible to save all kinds of data sing these commands, b t we will
firstly disc ss how to save simple n merical arrays these being the
easiest to nderstand.
Say for example that yo r program deals with stock control of p to 60
items. Yo may have a string array containing the names and a n merical array
containing the n mber of each item yo have in stock.
This wo ld se abo t 1K for the names and 300 bytes for the stock
fig res. However what if yo pdate the stock val e every week and yo want
to keep the last year of stock on record! Or even the last five years. Now
the fig res wo ld take p abo t 15K or even 75K.
These co ld be comfortably stored on disc, or even tape for a year's
stock, and the data read every time a calc lation was needed, b t yo
will probably agree that a long time wo ld be spent waiting for
reading the data each time a distrib tion is calc lated for each item.
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Obvio sly, it wo ld be easier to load all the records into RAM, then access
the data immediately:-
Instead of defining an array of dimensions 'stock(60,52)' taking over 15K of
val able RAM which co ld be sed for programs, define and array 'stock(60)'
Read all the data from disc a week at a time, and store each week of data
int o bank RA M. To do thi s yo n eed t o know tw o things. One, where
does the array lie in memory? and two, how many bytes is it necessary
to save?
1) Where is an array stored?
The address of any variable can be q ickly fo nd sing the '@' before a
variable. For example, dimension the above array:-
DIM stock (60)
Now type: PRINT @stock(0)
The comp ter will reply by giving the memory address where the first
element of the array is stored. Try:-
PRINT @stock(1)
The n mber ret rned will be five higher in val e. This is the address of
the second variable.
The '@' prefix will work in front of any variable. The first item of an
array is obvio sly '@stock(0)'. If yo are sing m lti-dimensional arrays,
the first item is '@stock(0,0)' or '@stock(0,0,0,0)' depending on the n mber
of dimensions.
2) How long is an array?
First of all, different types of array take different n mbers of bytes per
element. For real n mbers, there are 5 bytes per element. Integer arrays
take 2 bytes per element. String arrays are of variable length. And will be
dealt with later.
Next, the n mber of dimensions and elements needs to be taken into
acco nt. Remember that elements start from 0. This means that an array of
'stock(60)' has 61 elements. Whether or not yo prefer to se the 0 element
is p to yo , b t if yo forget it, there co ld be some nexplainable
b gs appearing in yo r program. Once yo know the real n mber of elements
in every dimension, simply m ltiply together all the dimensions to find
o t the total n mber of elements in all dimensions.
For example: 'stock(60)' has a total of 61 elements.
'stock(60,52)' has 61*53 elements = 3233 elements.
'stock%(10,5,12)' has 11*6*13 elements = 858 in all.
To find the total memory, m ltiply the total n mber of elements by the
amo nt of memory needed by each element.
For example: 'stock(60)' takes 61*5 = 305 bytes.
'stock(60,52)' takes 3233*5 = 16165 bytes.
'stock%(10,5,12)' takes 858*2 = 1716 bytes in all.
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The array we are sing is 304 bytes long, and starts at @stock(0). In a
single bank of RAM we can store 305 bytes abo t 53 times. The bank address
starts at 0 and goes p in steps of 305 bytes:-
0 305 610 915 1220 1525 etc.
We shall store week 1 at bank address 305, week 2 at address 610 and so on
for all 52 weeks.
Data for test p rposes co ld be written onto disc or tape by the
program below. Once the test file is written, keep it for se while yo
are developing yo r program.
10 OPENOUT "stock.dat"
20 FOR week=1 TO 52
30 FOR item=1 TO 60
40 Print#90, INT(RND(1)*3000+100)
40 NEXT item
60 NEXT week
70 CLOSEOUT
80 END
Now type 'NEW' and enter the following program:-
10 DIM stock(60)
20 INPUT "read file (y/n)";ans$
30 IF LOWER$(ans$)="y" or LOWER$(ans$)="yes" THEN GOSUB 1000
40 REM rest of program ....
1000 REM s bro tine to read data from disc.
1010 OPENIN "stock.dat"
1020 FOR week=1 TO 52
1030 FOR item=1 TO 60
1040 INPUT#9, stock(item)
1050 NEXT item
1060 |SAVED,4,@stock(0),61*5,week*305
1070 NEXT week
1080 CLOSEIN
1090 RETURN
The above program co ld be sed to read the file from disc or tape. Once
the file is in bank RAM, the contents will stay there for se ntil the
comp ter is switched off, or some other data is p t in that bank. This
means that data need only be read once from disc, then the program can be
rer n witho t losing the data. This co ld also be sef l too if yo
wish to write a n mber of programs to se the same data.
Once the data is in memory, yo can access each week's data simply by
reloading the stock array. Add the section below to draw a bar graph for a
given section.
100 MODE 2
110 LOCATE 1,1
120 INPUT "Which item to analyse",itemno
130 IF itemno < 1 OR itemno > 60 THEN 120
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