6502 Badge Nearing Completion


My copy of Lee’s 6502 Badge is nearing completion. Lacking only a 2mhz resonator and a slide switch that would fit the board, I have been forced to wait on parts from Mouser. 

I have, however, made some substitutions. Probably the most visible is the choice of EPROM. I have a 27C512 socketed. This is because one can use that as a replacement for the 27C256 provided he places the code in the top half of memory. Second item of note would be the connector that has been added to make a detachable battery pack. I thought it would be a nice addition. Third, I didn’t have the proper resistor arrays, so I used one that was close, and the other I substituted with upright resistors. There is nothing more retro than that… And the last substitute was to make odd sized capacitors work, and replacing the 560nF cap with a 100nF cap. I doubt there will be an issue here. Per my previous conversations with Lee I am under the impression that many times he chooses a part because it’s what he has ‘on hand’, and it works. The alternative was to go with a 560nF Tantalum. It would work, but I didn’t want anything that volitile on my chest (I have seen many Tantalum capacitors go ‘boom’ in my history with older computers).

But, a long story short I only lack those two components and burning the ROM in order to have a working example of Lee’s 6502 computer. 

But I have another problem. I’ve looked high and low, but have not found my TTL Serial to USB adapter. But, what I do have sitting on my work bench are a bunch of CH340G RS232 to USB ICs as well as plenty of 12mhz oscillators. Ok, so that’s something. I also have some MAX3232CPE RS232 to TTL ICs.  So I have options, and should be able to wire something up. I’ve never tried my hand at making my own USB to TTL adapter. But it could be neat. Especially since I have my own 3D Printer. I could make it look decent.

I’ll post an update as soon as it is finished.

6502 Badge Arrives


Thanks to Lee Hart, Retro Depot now has a couple of the boards for his and Daryl’s 6502 VCF Badge.

Since they just arrived in the mail there hasn’t been time to complete them. But that should be expected sooner rather than later. I believe the parts box even has a spare LED display left over from the z80 Membership Card that was built about two years ago.

In either case, as soon as it is completed you can expect a review. And the next time Retro Depot makes it to a Festival, I’ll have a nifty 6502 Name Badge / Conputer with me.

Maybe I should build a portable Terminal so that I can program on the go. Now that’s an idea….

Francois Rautenbach’s work on Rope Memory

The early computer and navigation systems used by NASA are extremely interesting, even in the modern day.  The ways that they computed, stored data, and were interacted with are quite different than what we typically think of when we reference a computer in today’s modern age.

However, Francois Rautenbach has been made aware of the discovery of  Rope Memory. And has worked quite hard on a method for dumping the programmed contents thereof.  The video is below.   And a followup video he posted sheds a little more light on the subject.  But my question I have to ask is, is the data still valid?  From what I can gather from my examination of the video, the module is made up of magnetic core storage, similar to early RAM.  And as such, likely lost it’s data a very long time ago.