With a very big pleasure my friend !!!!
every time that someone asks to me to tell more about the Plus/4, I am very pleased...
In my opinion, the Plus/4 was better suitable for programming and working purposes, instead of the C64 that is superlative, as we know, for gaming purposes... The Plus/4 was concepted as the "major brother" of the Commodore 16... in fact, while the C16 had only 16k free for the users (12277 bytes free) the Plus/4 has 60k free (60671 bytes free to be exact...) The clock frequency of Plus/4 is approximately of 1.75 MHz (instead of the 0.89 of the Commodore 64) and this makes the Plus/4 faster... The "gem" of the Plus/4 was the so called "3-plus-1" software package, that was pre-loaded into the machine... I can't put the images here because there is the copyright of International Tri Micro Inc. who realized the software but, if you try to start a Commodore Plus/4 emulator and type the "SYS 1525" instruction, or alternatively press the F1 key, it will start... The "3-plus-1" consists of four programs (a sort of ancient "Office" suite hehe...) that were: a word processor, a spreadsheet editor, a data management and a database creating program, that was very useful, even if they worked only with the disk unit and not with the Datassette...
However, the Plus/4 had some faults in the gaming area, for these reasons:
- first, unlike the Commodore 64 that had the VIC-II chip for the video and the SID chip for the audio, the Plus/4 was equipped only with a chip, the so called "TED" ("Text Editing Device") that controlled both the audio and the video sections... The audio section was very poor, in fact there were only three sound generators... two of them produced only square wave frequency sounds, and the third produced white noise...
And regarding the TED video section, even if the color palette was of 121 colors (8 shades per colors plus black), has not the sprite handling and the sprite collisions, so the movements in games are less fluid than the Commodore 64 ones... another problem is that the connectors and the sockets are not the same for the joystick and the Datassette used for the Commodore 64... in fact, Plus/4 is equipped with mini DIN connectors, while C64 uses Atari-style connectors...
However, my opinion is that Plus/4 is more excellent than the Commodore 64 for programming... even because it had built in the 3.5 Basic version of Commodore, instead of the 2.0 of the Commodore 64... many instructions for graphic and sound handling are dedicated, instead of the Commodore 64 that uses the PEEK and POKE instructions for each two parts... Here are some little examples:
Producing a sound on the Commodore Plus/4
10 VOL 8
20 SOUND 1,266,60
("VOL 8" tells the system to turn the volume at the maximum level, and the syntax of the SOUND command is the following:
SOUND (tone generator,frequency,and duration in milliseconds... in our case, we have chosen to produce a sound using the tone generator number 1, a frequency of 266 hertz, and a duration of 60 ms.)
You can also change the tone generator... the tone generator 2 is similar to 1 (so typing SOUND 1,266,60 or SOUND 2,266,60 is the same)... but if we want to produce a white noise of the same frequency level, we have to choose the tone generator number 3 (so SOUND 3,266,60 can fulfill our request...)
The frequency range goes from 0 to 1023 that is the maximum level and cannot be heard by the human ear...
For graphics area, we have these instructions:
GRAPHIC 2,0 (it switched the computer in hi-resolution mode, but it's unuseful, because "garbage" appears on the screen... the first pattern that I put on the images in this topic... probably, but this is a personal opinion, the pattern is generated from the decodings of 00 and FF instructions that put the Plus/4 in hi-res mode... the location in memory is $1C00, a couple of BRK instructions (blank spaces) and FF instructions (green reverse bars or arrow "@" signs...)
GRAPHIC 2,1 (Switch the computer in hi-res mode, but clears the video cache and the "garbage" of the pattern, so we can operate...)
GRAPHIC 4,0 (Multi color hi-res mode, but with pattern... the second, that with pink and white rectangles...)
GRAPHIC 4,1 (Multi color hi-res mode, but with screen cleared...)
Typing these command preserves the bottom of the screen with five text lines so we can introduce commands... otherwise, if we want to switch all the screen in hi-res mode, we have to type:
GRAPHIC 1,0 (full screen pattern)
GRAPHIC 1,1 (hi-res mode with completely cleared screen)
GRAPHIC 3,0 (full screen multicolor pattern)
GRAPHIC 3,1 (full screen multicolor area with screen cleared)
The most used commands for the graphics area are:
CIRCLE (for creating circles)
BOX (for creating box and squares)
DRAW (for creating lines)
PAINT (for filling an area with specific color)
CHAR (to display letters and numbers in the hi-res area)
In order to change the colors of the screen we have these options:
COLOR 4,X (changes the border color, for example COLOR 4,1 changes into black)
COLOR 0,X (changes the text area border, for example COLOR 0,4 changes into cyan)
COLOR 1,X (changes the letter's color, let's try to put it in blue with COLOR 1,7)
However, in the syntax of the COLOR command, we also have a third option, that determinates the luminance and the brightness... look at this:
COLOR 1,7,1 (Text color will change in dark blue)
COLOR 1,7,7 (Text color will change in light blue)
And so on... COLOR 4,7,1 or COLOR 4,7,7... COLOR 0,7,1 or COLOR 0,7,7 and so on...
Some other commands included in the BASIC 3.5
HELP (This helps the user in finding an error in a program list)
for example let's suppose that the computer says "?SYNTAX ERROR IN 10" we can type "HELP" and the machine will show us the line and the error in flashing characters;
DELETE
It allows you to delete an interval of lines in a program listing (for example "DELETE 10-50" deletes the lines from 10 to 50)
GETKEY
"GETKEY" has two variables, A or A$... If we enter "GETKEY A" the computer stops and waits for the user to hit a numeric key to continue, while with "GETKEY A$" the computer stops and wait for the user to press any key to continue... for example:
10 PRINT"HIT A KEY PLEASE"
20 GETKEY A$
30 PRINT"WELL DONE"
The DO-LOOP cycle that is similar to the FOR-NEXT on the Commodore 64 or to the GOTO instruction... have a look at this:
10 DO
20 PRINT"RETROMANIAX"
30 LOOP
in this case, is like typing a PRINT-GOTO cycle...
Also, a map of all the error messages is available with the function ERR$... the syntax is:
PRINT ERR$(X)
in this case, X is a number included between 0 and 255, every number shows us the correspondant error message mapped in memory
MONITOR
Typing "MONITOR" and hitting return causes the computer to start the TED machine code monitor... a feature that is not supplied on the Commodore 64 unless you have a cartridge with the program... But beware !!!! The register memory addresses of the TED are different than those of the VIC-II or SID in the C64, so programming and using the same values of C64 on the Plus/4 can cause the crash of the system, the apparition of the pattern with reverse bars, production of continuous tone sounds or white noises and so on...
DLOAD and DSAVE
These two commands allow the user to load a program from the disk unit... the same as LOAD"PROGRAM NAME",8 and SAVE"PROGRAM NAME",8 on the C64... on the Plus/4 you can type DLOAD"PROGRAM NAME" or DSAVE"PROGRAM NAME" to reach the same objective...
SCNCLR
"SCNCLR" stands for "SCREEN CLEAR", it allows to clear immediately the content of the text area (even if we are in hi-res mode) and replaces the PRINT"(key CLR/HOME and SHIFT)" statement of the C64
KEY
"KEY" shows a complete list of all the function keys from F1 to F8 in the Commodore Plus/4... When you type KEY and hit return, Plus/4 will show as follows:
KEY 1"SYS 1525: 3- PLUS -1"
KEY 2"DLOAD"+CHR$(34)
KEY 3"DIRECTORY"+CHR$(13)
KEY 4"SCNCLR"+CHR$(13)
KEY 5"DSAVE"+CHR$(34)
KEY 6"RUN"+CHR$(13)
KEY 7"LIST"+CHR$(13)
KEY 8"HELP"+CHR$(13)
The "CHR$(34)" means that Plus 4 shows a " sign, while the "CHR$(13)" stands for an automatic input of the RETURN key... but these function keys can be redefined by the user...
And other commands like TRAP,TRON,TROFF,OPEN,CLOSE,DIRECTORY,LOCATE,WAIT,COLLECT,HEADER that are not supplied with the Commodore 64...
I hope that you have liked this brief explanation !!!!
Hugs !!!!
[edit] Dead pic [edit]
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