Does Road Blasters or System 1 games in general blow bipolar PROMs ?

cwilbar

Well-known member
Joined
Sep 8, 2015
Messages
1,209
Reaction score
31
Location
Massachusetts
Does Road Blasters or System 1 games in general blow bipolar PROMs ?

I have 4 Road Blasters boards. One working one in my Road Blasters, and 3 others. All are LSI cart type.

2 of these have blow 136048-1172 PROMs.

And strangely while all my boards have that PROM, mame does not show a 136048-1172, it shows (from a google hit on some mame source):

ROM_LOAD( "135048-1172.d1", 0x000000, 0x000200, CRC(b79d1903) SHA1(8319fab8b39f708457eb1efe47789b26adc61249) )
ROM_LOAD( "135048-1171.d2", 0x000200, 0x000200, CRC(29248a95) SHA1(c9467d495676d323121c92c6757e73b2ed3fb3d7) )

ROM_LOAD( "136048-1174.12d", 0x000000, 0x000200, CRC(db4a4d53) SHA1(c5468f3585ec9bc23c9ee990b3ae3738b0309823) )
ROM_LOAD( "136048-1173.2d", 0x000200, 0x000200, CRC(c80574af) SHA1(9a3dc83f70e79915ce0db3e6e69b5dcfee3acb6f) )

so it shows a 1172 but for 135048 not 136048, but my parts (both the 2 bad and 2 good) are labelled 136048.

interestingly enough, my proms match mame's 135048 proms, but a comment above the definitions says:

// these 2 proms were present on this board, an earlier revision to the other games, however they don't give correct
// gfx, so we load the regular ones over, might need different GFX rom loading? investigate further.
// (the failure to use these roms properly might be the reason we have the IMPERFECT_GRAPHICS flag on this
// set in the first place)

and then they reload the 136048-1174.12d and 136048-1173.2d files over the loaded 136035 files.

Seriously ?

I'm having a hell of a time with bipolar prom verification in System 1 boards. Yowza.

Can anyone she some light on this, as well as if it is common for System 1 games to blow bipolar PROMs, or for RoadBlasters to take out 136048-1172 PROM (or whichever PROM is/should be in position 7A on an LSI cartridge Road Blasters ?????
 
*bump*

Still looking for the experience of others in regards to RB or System1 games in general blowing bipolar PROMs.
 
I don't know about System 1 games specifically, but in general, bipolar PROMs seem to go bad much more frequently than most chips (have you EVER found a Punch Out!! in the wild with all its PROMs still good? ;) ).

DogP
 
Back
Top Bottom