HP9835 ROM questions

[Paul Berger (Canada)]

I can provide you with a pinout of the ROm slots but be aware that the logic level on those card slots is 6V which makes it somewhat inconvenient to use them with modern devices. What I did was create a card that plugs into one of the connectors for RAM cards which are the more usual 5V logic level. My design was posted on hpmuseum.net, http://www.hpmuseum.net/upload_htmlFile/...AMCard.zip unfortunately on the page it only mentions RAM card but the packages contains the documentation for my ROM card as well as a schematic for the 9835 64K RAM card. I have also built a RAM expansion card using more modern static RAMs so now my 9835A has a little over 512K of RAM. I have not put together any formal documentation for my RAM card yet. Both of these cards where constructed as hand wired prototype cards. If you have questions send me an email and I will assist.

I have no experience with the test ROM in fact this is the first time I have heard of anyone having one. If you have not already done so you should get the service manual from hpmuseum.net as it explains how to use the service ROM. I would be very interested in a dump of this ROM and can help you with dumping it.

9835s don't seem to be all that common and since Mass storage is a very useful ROM the chances of finding one are probably not good.

For your 9885 diskette drive you will need a GPIO adapter with an appropriately configured cable. The 9895 is however HPIB and is likely more useful anyway.

A word of caution about the display connector it is keyed for very good reason, if you ever happen to plug it in backwards very bad things will happen.

Paul