What does this program

This program creates a file made of n partitions equally sized and puts in these partitions the files specified in the arguments. Blank spaces will be filled with 0xFF or 0x00 values. The user can choose:

• which file goes in each partition
• the lenght of the final image
• the number of partitions

Why did I make this program and what is it thought for

I made this simple program because I erroneously bought some W27C512-45Z EEPROMs for my Acorn BBC Master Compact, an old 8-bit PC. It has 5 EPROM slots. When buying my W27C512-45Z EEPROMs I didn't know that only the system OS ROM slot is 64kbyte capable and that all the others are only 16kbyte capable exception made for one that is 32kbyte capable. This means that I should have had buy some D27128 EPROMs instead of W27C512-45Z EEPROMs.

Anyway, since W27C512-45Z are four time bigger than D27128 I decided to unplug the two A13 and A14 address lines from the ROM socket and connect a switch to them so that I can switch between 4 ROM images using the same ROM IC. In the Acorn BBC Master Compact PCB A13 and A14 are tied to Vcc. The two switches per ROM IC should connect the two address PINs to GND or Vcc depending on which image in the ROM I would like to access.

This tool is thought to merge four 16kbyte ROM images into a sigle one for a 64kbyte ROM but these parameters can be modified.

How to compile

gcc ROM_image_generator.c -o ROM_image_generator

Tested in Linux, Windows and MacOS.
A 32-bit Windows binary ROM_image_generator.exe is provided in this repo toghether with an Apple silicon M1 one ROM_image_generator.macM1.

How to use it, example

$ ./ROM_image_generator utils basic48 adfs210
Input the memory size in bytes. (0 for 65536): 0
Input the number of equally sized partitions. (0 for 4): 0
Input if to fill blank partitions with ones (1) or zeros (0): 1
Found 3 files. Choose where to place them.
partition 0 @ 0x00000000-0x00003FFF filled with file: adfs210
partition 1 @ 0x00004000-0x00007FFF filled with file: basic48
partition 2 @ 0x00008000-0x0000BFFF filled with file: utils
partition 3 @ 0x0000C000-0x0000FFFF filled with FFs
Apply changes? (y or n): n
Input which partition to swap.
Partition number: 3
goes to number: 1
partition 0 @ 0x00000000-0x00003FFF filled with file: adfs210
partition 1 @ 0x00004000-0x00007FFF filled with FFs
partition 2 @ 0x00008000-0x0000BFFF filled with file: utils
partition 3 @ 0x0000C000-0x0000FFFF filled with file: basic48
Apply changes? (y or n): y
Writing "ROM_image.bin"...

Then if using a TL866II+ programmer with the minipro command line tool, the immage can be flashed with the command

minipro -s -p "W27C512@DIP28" -w ROM_image.bin

The -m option can be used in place of -w to verify that the write process completed correctly.
Compatible devices can be listed using the -L option like in the following example

$ minipro -L W27C512
No TL866 device found. Which database do you want to display?
1) TL866A
2) TL866II+
3) Abort
2
W27C512@DIP28
W27C512@PLCC32

Bash script version of this program

Bash versions of this program plus one that splits a 64Kbyte image into four 16Kbyte images can be found in the bashVersion/ folder in the root directory of this repository.

PCB projects I made using this tool

• Acorn BBC Master compact cartridge
• Acorn BBC Master compact cartridge ZIF
• Acorn BBC Master Compact 128K system ROM