Dual Boot R-Type 1 & 2 Arcade PCB - Day 5
Okay.. bit of a last-minute update, but..
I went and carried out the last "mod-routing" and only ended up needing two of the 74LS157 chips I had fitted.
(The last mod was where a logic chip had it's pin cut - I used one section of the second multiplexer to switch between "cut & patched" and "uncut")
Beyond that I discovered why the sprites were solid-blocks of colour (in the R-Type 2 mode).. really kicked my self.
Turned out that in my haste to burn those double-size Roms, I accidentely put the N0,1,2,3 data onto 4Mbit chips - instead of the 2Mbit type needed! :/ *facepalm*
That ment the middle of the Rom - in memory terms (where R-Type 2 sits) was in the wrong place! ¦D
Had to wipe 4 of the original Par-Type 1 (27C020) chips, as I had none left..
Dropped in some minty fresh dual-boot 27C020's into the N0,1,2&3 locations - and wired A17 (rather than A18 as with the larger chips) to the orange game-select wiring.. and the sprites came back!
Next I had to solve the problem of dual-booting the audio Rom..
Problem was that the next chip up in size had 4 more pins :'(
- luckly most pins match & only some minimal patching is required (Big thanks to t-m for suggesting this!!! a great idea!).
Here's the upgraded (double-sized 27512) SP chip using a 27C010:
Tidy hack this one ¦)
The four spare (patched) pins hang over the end of the socket - but to no ill effect.
And here she is in all her glory! <3
One orange wire bridges across from the top to the bottom board.. might fashion a removable plug / patch cord for this :/ hmm..
..All that's left to do now is replace the Major-Title VO-Rom (sound-sample) chip with the R-Type 2 version.. (in the morning, I'm tired now!)
..and, that will fix the dodgy RT2 samples playing crowd noises!.. and that folks.. is pretty much it!
I think we can safely declare this one Job Done! :D
Again, a huge thank you to Paul Swan & Chris Hardy for the original conversion techniques!!
(hope you guys approve of what became of it..) ¦)
And a million thanks to all of the members on Jamma+ - without whom I would never have happened across the knowledge, tools and techniques needed to carry out this job, cheers!!!
And Happy New Year!