VectorGlow
Student
I've recently been sent a System 32 boardset where an attempt had been made to convert it from F1 Exhaust Note to SegaSonic Rev A (Japan, prototype). The ROM board type is 837-7429-01
The game wouldn't boot but on replacing a corrupt EPROM it now boots into SegaSonic Rev A and can be coined but not played (seems to crash) - attract mode is okay though ....... unfortunately some (but not all) of the sprites are corrupted (horizontal coloured dashes spread out where some sprites should be) the and there's no sound. The F1 Exhaust Note was apparently working fine before the conversion and plugging in a known good ROM board (with Spiderman in this case) reveals that the graphics and sound problems are NOT due to any main board issues.
However, I suspect this is down to EPROM capacities - I can see from dumps of this game and others that the binary file size is 1,024K bytes for the sprite ROMs (for example) - this would seemingly match up with the 32-pin mask ROMs which would normally be used. However, 27C040 EPROMs have been used as replacements for the 1,024K mask ROMs with the prototype graphics and some sound data and they only contain 512K of data, meaning that half the data is missing. I'm not aware if any 32-pin EPROMs which would contain 1,024K bytes and so act as suitable replacements, and I don't want to go down the route of piggy-backed more than a dozen.
I am though still half asleep so maybe I've made an error somewhere.
Feel free to correct me if I'm wrong.
Edit: remembered that there is a possible EPROM for those 1,024K files, namely the 27C080 / 27C801 - programmed up three for the sound code (the first one of the four for sound is a 27C2001) but still no sound. No idea now if I have an EPROM or a jumper issue.
The game wouldn't boot but on replacing a corrupt EPROM it now boots into SegaSonic Rev A and can be coined but not played (seems to crash) - attract mode is okay though ....... unfortunately some (but not all) of the sprites are corrupted (horizontal coloured dashes spread out where some sprites should be) the and there's no sound. The F1 Exhaust Note was apparently working fine before the conversion and plugging in a known good ROM board (with Spiderman in this case) reveals that the graphics and sound problems are NOT due to any main board issues.
However, I suspect this is down to EPROM capacities - I can see from dumps of this game and others that the binary file size is 1,024K bytes for the sprite ROMs (for example) - this would seemingly match up with the 32-pin mask ROMs which would normally be used. However, 27C040 EPROMs have been used as replacements for the 1,024K mask ROMs with the prototype graphics and some sound data and they only contain 512K of data, meaning that half the data is missing. I'm not aware if any 32-pin EPROMs which would contain 1,024K bytes and so act as suitable replacements, and I don't want to go down the route of piggy-backed more than a dozen.
I am though still half asleep so maybe I've made an error somewhere.
Feel free to correct me if I'm wrong.
Edit: remembered that there is a possible EPROM for those 1,024K files, namely the 27C080 / 27C801 - programmed up three for the sound code (the first one of the four for sound is a 27C2001) but still no sound. No idea now if I have an EPROM or a jumper issue.
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