[Techtoolslist] 6502 pods & clocks....

[John Robertson]

Hi Matt (and everyone else),

If I had time I'd make a small PCB for the 6502 pod that had 28 pin 
sockets (use a short 28 to 28 - UUT - header jumper) for the other 
common (at least I run into them) variants - the 6503 and 6504 (6005 
too, what the heck) as 28 pin sockets. How many people would want such 
an animal? Figure the run cost at around $200, need about $50/PCB for 
four people to make it of any use to consider making.

There are clever folks here who could do it more economically and faster 
(I'm not that good on Kicad yet) who are welcome to offer doing it!

Then you could have a simple jumper to add the 1mhz R/C clock (it is a 
7404 with a 16nf and 220R hookup) signal to the Phase 0 in, My adapter 
is ugly - consists of one of the Fluke 40 pin extender sockets (so you 
could monitor the various CPU pins) that was damaged and hard wired a 28 
pin jumper cable to that so it matched the needs of the 6504. Need a 
pullup resistor for the Ready line too. The adapter has a tiny PCB at 
the bottom which is the width of the pins and length of the socket, so I 
could squeeze in the 7404 and the caps (use 15n and a 1n to get the 16n) 
and resistor - don't think it will show clearly in a picture, but if I 
have time I'll take some shots and add it to my Fluke page on flippers 
(and post a followup).

John :-#)#

On 11/08/2013 10:32 AM, Matthew Rossiter wrote:

> It's too bad email doesn't have a 'Like' button.

>

> Would you be able to share some photos of this on your site?  I'm 

> interested in this idea.

>

> Matt

>

> On 11/5/2013 5:22 PM, John Robertson wrote:

>> On 11/05/2013 3:18 PM, John Robertson wrote:

>>> Tic, tock...

>>>

>>> The 6502 will clock from either a crystal or an R/C system. The 

>>> problem with the R/C is the capacitor is only 10pf, so the cable 

>>> capacitance will sloooowwwww the clock down somewhat (900kz to 500kz 

>>> or so).

>>>

>>> So, being impatient I'm making a simple 7404 1Mhz R/C clock that 

>>> fits into the Fluke adapter socket and will drive the UUT 6502 CPU 

>>> directly, thus the pod won't interfere with the clock frequency and 

>>> I won't get any more timeout errors (I hope).

>>>

>>> John :-#)#

>>

>> Yes, that did work, I was getting timeout errors with the original 

>> R/C clock and now my little 7404 R/C clock has tidied up the signal 

>> and is driving at 900kz which is just fine for testing. I'm now 

>> getting reliable learn, etc. functions.

>>

>> John :-#)#

>>

>

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