mardi 6 juin 2017

RETROCOMPUTING & APPLE //e

Few months ago, I recovered an 'old' Apple //e in a non-functional state, with others vintage materials. This Apple //e don't start an do nothing, in truth! Some inspections of the motherboard reveals that few ICs aren't correctly inserted on their sockets, some of them were even in the wrong position. The video UVPROM were mising etc etc...

So, I got myself all the TTL ICs that were supposed to be defective on the motherboard, I burned a new UVPROM with a French video generator, plus I made some corrections on the board :


After having done this modifications, again, nothing worked, exept a flashing white/black screen. At this stage, an very imortant thing : To start, an Apple //e need to have its keyboard attached!

After have plugged the connector of the keyboard and switched on again, TaDa :

The first Propgramm since... a very long time.

In this configuration, the main board is equiped with a 64K Apple memory card and runs the basic interpreter as soon as power is turned on : great!

Now, I have to put this main board with the PSU and the keyboard back into the original case, and to test the two floppy drives with the expansion board.

PSU

Main Board

Keyboard

Ext Cards
Hum : The disk I/O card is in a wrong place. This card MUST NOT be installed into the GAME I/O slot!

And after have placed the cover and powered this Apple //e :

Yessssss
I would have been happy but after few minutes, this //e started to have problems and finnally went faulty with a very characteristic smell of burnt electronics. After some research I understood that it came from one of the floppy disk drives. Incredible, here is what I discovered inside one of them :


The 74LS125 burned without reason. A check of the voltage revealed a very good value of 4,97V on it! I never saw that befor, exept with the good reason of overvoltage.


The trace of smoke deposited on the top of the floppy drive indicates that the 74ls125 has reached a very high temperature... So I replaced it with a new one :


Finally, the system works very well with the two drives attached on it :

CTRL + CLOSED APPLE + RESET or APPLEs at POWER UP

But I don't have any Pro DOS floppy to boot with. And I don't know how to find that! Actually I must stop the boot process with the CTRL/RESET keys and go to the internal Basic interpreter. A good solution could be the use of an Apple // disk drive emulator like this :


Extension cards for the Apple II? 

https://quip.com/ :


ADP Pro :   



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