Here is one of my Commodore Plus/4'sThis computer was the first real computer I owned that wasn't a Binatone TV Pong clone, or handheld electronic LED Space Invaders gameI have many happy memories of this system, playing great games like Jack Attack, Winter Events, and all the Mastertronic titles
I have two of them, but they were both not working, one of them had a blown CPU, and the other one had errors in BASIC (TED, BASIC ROM, RAM?)
One of my Plus/4's donated the case and keyboard for my Raspberry Pi Zero Plus/4 project
At the moment this is the machine with the blown CPU, this does nothing more that show a black screen on boot up.Let's have a look around the unit first...
This is a machine that suffers from heat issues, so as you would expect, there are a lot of vents around the machine
On the back (from the left) is the power socket, this is pin compatible with the Commodore C64 PSU, but has a strange square plug. Next is a Serial port, then the Cassette port, which is different to the C64, A User port and Memory expansion are next. Then there are two mini DIN joystick ports, no Atari compatible ports here, Commodore gave the reason of less RF interference for using mini DIN sockets, but you could get adaptors for normal joysticks. Then finally a Video socket for a monitor.
On the right hand side of the machine is the toggle power switch and reset switch, and on the left is the RF television socket. In some regions there was a H-L switch to select the channel the machine uses
This is the board I took from the other machine, this one booted, but had errors in BASIC, which may be due to bad RAM, Bad ROM, or a bad TED.You may notice the missing power switch, reset button, and keyboard connector. These were borrowed for the Raspberry Pi Plus/4.
Two machines equals two Datassettes, there are subtle differences between the two Datassettes, which could be because they were made in different factories?
This is the same power supply used for other Commodore machines, just with a strange square plug
Anyway, swapping the good CPU from the donor board with the dead CPU allows the machine to boot normally, however not all the keys on the keyboard work, this could be due to the ribbon connector, which is notoriously fragile, I will have to swap it with pin headers and dupont wires
But holding down the RunStop key and resetting the machine brings up TEDMON, so that key is working at least.
Also the replacement CPU feels hot, hotter than I'm comfortable with. So some heatsinks will be required.
I had tested the PSU's voltages and the 9Vac line was testing at 9.5Vac with no load, the 5Vdc line was reading 5.3Vdc with no load, this is the absolute maximum as the Plus/4, like most of the Commodore 8 bit machines are not tolerant of over voltage on the 5V line.
Hardware updates
I have managed to get what claims to be "a fully working" machine, so we'll take a look...
I only got the computer by itself, so I will need to dig into my box of Plus/4 goodies to test it
First thing is to test the voltages to make sure they're within spec. Today the the AC line is measuring as 9.9V and the DC line is 5.3V, which is good
Plug in, hold breath, switch on, and it boots
3-PLUS-1 ON KEY F1 to start...
Hold the Commodore key and press C, then type TC to get to the spreadsheet, then TW to get back to the word processor
Usual BASIC programme working just fine
Testing the sound, I couldn't remember the variables, the last command is the one you want
SOUND 1,500,50 and SOUND 2,500,50 should produce a short beep from the TED, using SOUND 3,500,50 will produce white noise
Top and bottom
This one does appear to work, but I'll need to get a modern PSU and heat sink the TED and CPU before using it in battle
Software
These are the cassettes that originally came with the Plus/4, except the last one, I don't know where that one came from.Back in the day I had the cartridge pack bundle, but managed to get a copy of these cassette games onto a blank C90, and I must of had most of the games ever released for the systemDisk drives? What are they? Sounds expensive to me!
Fire Ant
Exorcist
Number Chaser
Number Builder
Space Sweep & Invaders
Crazy Golf
Icicle Works
Harbour Attack
Mayhem
Treasure Island
Climb-It
Now I just have to fix the keyboard, install some heatsinks, and acquire a modern PSU to test if there are any other problems with this machine...
3 - Subscript wrong, 482:1