Creating a ROM Image with bvi Topic:Electronics   Date: 2004-04-29 Printer Friendly:   Mobile View:

You can use bvi to create and edit image files. We are using this to create a poor man's PAL using old 2716 EPROMS, but there are certainly other uses. Start by setting the mode memmove. This will let you expand the file on the fly, something that is a bit rare with binary editors:

usr-1@wrk-1 o2 $ bvi ruk 00000000 01 . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ :set memmove

I inserted 01. I want to fill up the ROM with that for now. The decimal repeat commands don't seem to work right with the version of bvi I'm using, but just hold down the . key, and you can fill up 2048 bytes pretty quickly:

000007B0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ 000007C0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ 000007D0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ 000007E0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ 000007F0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ 00000800 :wq

Let's check out the size:

usr-1@wrk-1 o2 $ ls -l ruk -rw-r--r-- 1 usr-1 users 2048 Apr 29 04:08 ruk usr-1@wrk-1 o2 $

Cool. Let's edit FF:

000000E0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ 000000F0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 02 ................ 00000100 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ :wq

Bvi also comes with bmore, which we can use to verify our file:

usr-1@wrk-1 o2 $ cat ruk | bmore 00000000 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ * 000000F0 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 02 ................ 00000100 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ................ * usr-1@wrk-1 o2 $

Very nice. We can burn this image directly on to a 2716 EPROM.