6502.org

well I was looking up parallel standards on "how stuff works"

http://electronics.howstuffworks.com/parallel-port1.htm

hmm so I guess I decided which format I wish to use as pc's these days appear to support all the new ones!

http://electronics.howstuffworks.com/parallel-port2.htm

I wish to make a cable + circuit so I can write to sram - has anyone tried this with older parllel standards?

how do parallel port (hardware programmers) usually go about address select and write! with parallel port - not a human programmer I'm talking about the hardware!

do they select an address using e.g. 15 pins for 32k sram

latch that and then send the data down the line using e.g. using 8 pins for data (1 byte word).

I comes back down to this rom being too expensive for me to currently program and I feel I could try some things using this method.

what I mean is because I'm not worried about loosing the information when the powers off - I dont care about portability keeping my rom intact, I want to write to a sram chip while the powers on and call that my rom - so once written I set the r/w line to read - high? if I remember correctly.

I already have guessed there might be 1 or 2 things that are incorrect in the above post

hmm well it seams that parallel standards have changed a fair amount like 3 or 4 times over the years..

1. I think I will use the new pinout called EPP as this is designed for data transfer to other devices - even handling high speeds of up to 2 meg a second (apparently possible), where as on the other hand the newer standard ECP is designed for better printer communication!

2. I was thinking of what I wrote above in a hurry, because the newer standards even the EPP one have some form of control as well as data pins - (ignoring the fact that you can use 16 pins for full-duplex now), I was thinking of having a 16 bit binary counter controlled via a reset and possibly a strobe pin - if a strobe pin is a good choice for triggering the counter!

and yeah just incrementing the address line that way - its latched and recognised the same time as sending the data!

is this method ok?? - any ideas, do you guys know how much current sram typically uses for read write on the data pins - will I need external powersource for that or will the parallel port simply give me enough juice - as well as keeping in mind safety precautions e.g. diodes on the datalines, maybe resisters?.

take a glance on www.beyondlogic.org - they have all information you want to know...

yeah thanks very much for that interesting link!