The HP Portable Plus computer ROM Drawer uses 28 pin 1MBit (128K) Mask
ROMs (TC531000) or 512KBit EPROMs (27C512).
A few years ago a company called Personalized Software made something
called a ROMBO. This was an adapter that allowed the use of a 32 Pin
27C010 Quad Pack and plugged into the 28 pin socket on the ROM Drawer.
The down side of this was that the ROMBO needed a special EPROM
programmer to program. Here is a link to a picture of the ROMBO. These
are no longer available.
https://drive.google.com/file/d/1VKaWpfTIgDriStECXqfptBjHoL6wEmN6/view?usp=sharing
I am thinking of doing something like the schematic linked below to use
a modern flash chip (AT28C010) in place of the 27010 and bring out the
three pins necessary for programming to jumpers that can be connected to
a flash programmer (or I might make an adapter board that the board
plugs into for programming).
https://drive.google.com/file/d/18RsZPBJldTyxzjozVlO9okfpgOK7P2QT/view?usp=sharing
Has anyone made anything like this for the portable plus or seen
something similar.
I also have the following questions:
1. Is there enough room in the ROM Drawer for some kind of socket on
the adapter board?
2. Where can I find the low profile pins used in the ROMBO?
3. Have I missed anything?
Thank you...
