I have here is a version using a 4Kb 2732 EPROM (I assume a 27c32 will work as well). Have a close look at the wiring and compare them to the schematic to get a clear look. I have lifted the pins of the topmost socket to alow rewiring to the bottom pins which connect the the VIc 20 mainboard. I plac...

Here is a suggested mod to this PCB. IMG_20201026_144521.jpg IMG_20210719_152437.jpg IMG_20210719_163118.jpg If you look carefully You will see that I used cut off resistor wires to make pins that one can use to plug a jumper wire between a standard C64 ROM configuration and the Vic 20 Character ROM...

Hi Philip L, Apologies for not carrying on with this VIC 20 Character ROM adapter PCB project. I have been a bit lazy. I will now try to explain my take on what I did. Please don't hesitate to add or comment. The more information on this the better I feel. First of all I would like to thank eslapion...

Hi eslapion,


Great Idea!

Hi eslapion, Yes, you're right. As a very mediocre hobbyist I continually find myself faced with more questions than answers the further I stumble along. I appreciate all the help you have given. It must be very frustrating to deal with the likes of indiduals such as me. I will get back to investiga...

Hi eslapion, Thank you for the valuable feedback. Much appreciated! Thank you for the link to Kirchhoff's voltage and current laws. lots of reading there to keep me busy.... I think my analog multimeter consumes about 20mV. An impedance load draws CURRENT, not voltage. Thank you for the clarificatio...

Here is a Chinese knock-off (fake). The printing on the chip is very hard read . When I cup my hands over the circuit, not physically touching any part of the circuit the knock-off 74LS279 latching IC will trigger all by itself.
It is quite unusual behaviour.

Some more.....

Here's some more readings from different 74ls279 latching IC's