Apple II Eprom Writer - Ap-64E

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A2forever's picture
Last seen: 7 years 5 days ago
Joined: Dec 20 2003 - 10:38
Posts: 226
Apple II Eprom Writer - Ap-64E

I have a Ap-64e Eprom Writer... It's been quite awhile since I have burned any eproms , so I am trying to get back into using them again. I have a Disk with eprom files on it , they are in Binary form. I'm not exactly sure what address to BLOAD them into memory , so I can put in the starting address that the card asks for? It's possible that I have bad eproms , 2716 , because of the check error that occures after burning. I have some on the eraser at the present time and will try again. I have already selected the correct dip switch settings for the type of eprom that I am trying to burn. So if someone can please educate me on the correct methods of this card , that would be awsome. And also , if someone could recomend me a good eprom eraser , even better :O)



Last seen: 3 years 11 months ago
Joined: May 17 2017 - 03:28
Posts: 14
Re: Apple II Eprom Writer - Ap-64E

And some nine years later.....

There are some unknowns here, primarily the exact brand/part number of the EPROM being programmed. The AP-64e isn't anywhere nearly as flexible as other programmers because the Vpp voltage is fixed, and can't be changed by software. Depending on the part being programmed, the Vpp can range anywhere between 12VDC to 21VDC. Most parts have a small tolerance range, so your particular AP-64e must be calibrated according to the specs of the part, which you can get off the data sheet for that part. This voltage is what causes most EPROMs not to be programmed correctly, regardless of the DIP switch settings on the AP-64e.

As an example, an AMD 2716 has a Vpp of 12.5VDC. Therefore, the AP-64e has to match that voltage. The 2716's Vpp is on pin 21, and GND is on pin 12. However, voltage is only sent to the EPROM during programming. So, instead of measuring the voltage at the Textool, you can measure the voltage on the diode at D1. You would then use the trimmer at R2 to adjust the voltage that is needed for the EPROM. The trimmer controls the voltage coming out of the TL497 chip.

I've seen some bootleg AP-64e's where R2 is just a resistor. This means the voltage is fixed on the card. In order to adjust the voltage, you'd have to change R2. The documentation that comes with the AP-64e doesn't talk about this, so you would then need to read up on the TL497 chip to figure out what the value of R2 should be.

One other thing that can screw things up is the orientation of the EPROM in the Textool. Earlier versions of the AP-64 has a 24-pin Textool. But, AP-64e has a 28-pin Textool. So, if you're using a 2716 or 2732, you must remember to place the chip at the bottom of the Textool (i.e. pin 12 on a 2716/32 EPROM should be touching pin 14 on the Textool.) This allows pin 23 on the Textool to line up with pin 21 on the 2716/2732. And, make sure the DIP switch settings are correct, as the DIP switches are used to correctly orient the Vpp voltage to the right pin on the Textool.

--- groinsan

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