[zxspectrum] emulazione spectrum +4 su mess
- From: "ZaXxon" <davidebressanini@xxxxxxxxxxx>
- To: <zxspectrum@xxxxxxxxxxxxx>
- Date: Wed, 20 Aug 2008 01:51:08 +0200
oggi stavo emulando con il mess quando mi sono accorto che tra le macchine
emulate c'e' una fantomatica (almeno per me) amstrad spectrum +4
alla partenza la schermata e' completamente nera e la presentazione riporta
questa scritta:
AMSTRAD CONSUMER ELECTRONIC PLC
(C)1982-2000 unofficial +4 48k
mi sembra di capire che non esista una macchina fisica denominata +4.
probabilmente conoscerete gia' questa variante. comunque, se cosi' non fosse
o per chi non avesse mai emulato col mess riporto il testo visualizzato
nell'apposito riquadro dall'emulatore.
Amstrad Spectrum +4 Rom
The plus4.rom is copyright (c)1982-2000 Amstrad plc and is distributed with
their kind permission.
I would like to thank Cliff Lawson and Amstrad for making this project
possible, Phillip Kendall for the Spectrum ROM page, Ian Collier for
documenting the changes he made to the ROM and giving me additional advice,
Dr Ian Logan and Dr Frank O'Hara for the invaluable Complete Spectrum ROM
Disassembly, and whoever it was that sold the book to me and contributors to
comp.sys.sinclair for keeping me constantly amused and informed.
-Andrew Owen, 24-2-2000
Introducing the Spectrum +4.
Remember when Apple promised its customers a whole new computer for $99.
What they meant was they hoped their new operating system would change the
experience of their users so profoundly it would make them feel as if they
had a new machine. Well now you can have a whole new Spectrum for FREE!
What is the idea behind this?
I've taken the original 48K machine as my starting point and tweaked it
until the point where I don't think there is any further room for
improvement without adding extra hardware. Now if someone wants to build a
new machine at least they have a place to start.
How compatible is it?
The Spectrum +4 ROM is very similar to the one in the 48 and so it should be
90% compatible or better with machine code. BASIC programs may require minor
modifications but should then run without problems.
What are the changes?
There are so many changes that it is impossible to summarize them all. Only
the important changes have been detailed with the exception of the new NMI
routine which is self explanatory.
THE KEYBOARD
The keyboard layout has been completely redesigned, based on the standard
international English keyboard, to make it quicker to use and easier to
remember which keys are where. This is made possible by replacing the
keyword entry system.
All the SHIFT functions on the number keys are retained, as are the EXTEND
and SHIFT-EXTEND attribute functions. But that is where the similarity to
the old keyboard ends.
All but a few symbols are accessed by holding down SYMBOL shift and the
relevant key, while the remainder are accessed using EXTEND mode. Pressing
either SHIFT or SYMBOL shift in EXTEND mode will give the same result as if
SYMBOL shift alone had been pressed. In addition to the characters shown
below, the 16 pre-defined graphics characters are accessible using SYMBOL
shift or EXTEND mode and keys Q-R and A-F.
--------------------------------------- | ! | @ | £ | $ | % | ^ | & | * |
( | ) | | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0
| ---------------------------------------- | | | | | | | { | } | : | " | | |
| | | | | [ | ] | ; | ' | | Q | W | E | R | T | Y | U | I | O | P
| --------------------------------------- | | | | | | | | | _ | + | | | | |
|(c)| | \ | - | = | | A | S | D | F | G | H | J | K | L
| ----------------------------------- | ~ | | | | ? | < | > | | # | | | | /
|, | . | | Z | X | C | V | B | N | M | ---------------------------
SYMBOL = Lower symbols EXTEND = Upper symbols and attributes on number keys
SHIFT = Upper case letters and functions on number keys
BASIC EDITOR
The most noticeable change is that all commands must be typed in full.
Instructions are converted into tokens automatically when you press ENTER.
It is also possible to use the cursors to move up and down while editing a
line. Instructions can be entered in both capital and lower letters. No
space is required between commands such as DEF FN or after a command unless
the argument begins with a letter.
BASIC COMMANDS
CAT, when entered without parameters, calls up the built-in monitor.
The PLOT, DRAW and CIRCLE commands have been modified to use the whole
screen.
ERASE "i" erases extra Interface 1 variables, extended channels and such
without affecting the BASIC program in memory.
The GO SUB, GO TO and CONTINUE commands have been replaced by GOSUB, GOTO,
and CONT, to replicate other BASIC interpreters.
MOVE can be used to shift data around in memory. For example, the command
MOVE "r0, 6144", "r16384" would copy the first 6144 bytes of ROM to the
screen area of memory.
The COPY command has been replaced by the FREE command which reports the
amount of free memory below RAMTOP.
THE MONITOR PROGRAM
The Spectrum +4 features a built-in monitor which can be accessed with the
CAT command or holding down SYMBOL shift, SPACE and B while interrupts are
enabled. The following commands are then available:
B Return to BASIC (if possible)
D<hex_num> Displays entered hex number in decimal notation
G<hex_addr> Execute a subroutine at address G (RET will return to the
monitor).
H<dec_num> Displays entered decimal number in hex notation
M<hex_addr> Hex and ASCII dump from given address (SPACE to exit).
R View and/or change registers AF, BC, DE, HL, IX and SP.
S<hex_addr> Patch memory from given address using hex editor (SPACE to exit
editor).
BUG FIXES
Every effort has been made to fix all the bugs mentioned in The Complete
Spectrum Rom Disassembly and a few others besides as follows:
Fixed a bug the CLOSE # bug. eg CLOSE #4
Fixed the forwardspace (CHR$ 9) bug. e.g. PRINT "A";CHR$ 9;"B"
Fixed the backspace (CHR$ 8) bug. e.g. PRINT AT 0, 0;CHR$ 8;"A"
Fixed the STR$ bug. e.g. PRINT "BUG"+STR$ 0.5
Fixed the division bug. e.g. IF 1/2<>0. 5 THEN PRINT "BUG"
Fixed the -65536 bug. e.g. PRINT INT -65536
Fixed the SCREEN$ bug. e.g. IF "X" = SCREEN$ (0, 0) THEN PRINT "BUG"
Fixed the "scroll?" bug. Try pressing True Video at the request.
Fixed the syntax check error.
Fixed the double store bug at 257Dh.
Resolved the K-MODE bug. There is no 'K' mode.
Resolved printer buffer error. There is no COPY command.
Resolved the NMI bug. There is a different routine.
Fixed the 'lock up if interrupts are disabled on error report' bug
LEGAL NOTICE FOR THE CURIOUS
Just to make sure it was 100% okay to do this I wrote to Amstrad's Cliff
Lawson on 23/02/00. Here's what followed.
ME: I know it's okay in principle to distribute modified Spectrum ROMs as
long as the copyright message is unchanged. However, I've just finished a
very major overhaul of the ROM and would like to use an alternative message.
CL: Well you can't really associate a name such as "+4" with "Amstrad
Consumer Electronics" because it makes it look as if it's an "official"
development.
ME: Would this be acceptable?
AMSTRAD CONSUMER ELECTRONICS PLC (C)1982-2000 unofficial +4 48K
CL: Yup, sounds OK but you do realize that the company was only called
"Amstrad Consumer Electronics" for a few years in the early..mid 80's then
the company name was shortened to "Amstrad plc" so it's a bit "out of date"
to use it but I guess that probably describes the "Spectrum" too! :-)
ME: Mind if I quote you in the "readme" just so no one accuses me of
violating copyrights?
CL: No problem.
Visit the Amstrad website at http://www.amstrad.com
Amstrad plc. Registered in England No. 955321 Registered Office: Brentwood
House, 169 Kings Road, Brentwood, Essex CM14 4EF, England
notte ;o)
--
ZaXxon
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