Sunday, 30 December 2012

Dual Boot R-Type 1 & 2 Arcade PCB - Day 5

 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!

Saturday, 29 December 2012

Dual Boot R-Type 1 & 2 Arcade PCB - Day 4

 Dual Boot R-Type 1 & 2 Arcade PCB - Day 4

Have made progress with the dual-boot electronics, and feel about half way towards finishing the job.!

First I installed three 74LS157 Multiplexers into the three remaining spare chip-sites (lovingly provided by iRem \o/). <3

(The green hoops bring +5v to the chips VCC pins of the 157's - as the top corner pins of the chip-sites are wired to the 5v rail)

Next I wired all the /CS (chip select) pins to ground.. which switches the three chips on permanently..

Then back on the top side; the orange wire carries the game-A/B (0v/5v signal from the hack above), this is wired to the select pins of the multiplexers - which will switch between the R-Type 1 & R-Type 2 signals.

Next I moved the four green wires that went into the board where the tracks were cut (in the original mod (on the left)) to the A0, A1, A2 & A3 inputs of the first multiplexer. These green wires carry the modified R-Type 1 signals.

I then took four yellow wires from the Y0, Y1, Y2 & Y3 outputs to the four points on the board (where the green wires came from)..

Then from below I found 4 board locations that connected to the original four traces that were cut in the original R-Type 1 mod & connected them to the B0, B1, B2 & B3 inputs of the multiplexer.. The red wires carry the original unmodified signals, which are used by R-Type 2.

Upon booting her up, I was greeted with a lovely sight: a nice R-Type 2 boot screen and working backgrounds!! ¦D

Later tonight I'll route the remaining board mods through the second 74LS157 and hopefully bring the sprites back! 
I then plan to use the third chip (if neccesary) to handle the audio Rom selection duties..

Fingers crossed It should all be running this side of the New Year!! :D