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

Wednesday, 28 November 2012

Dual Boot R-Type 1 & 2 Arcade PCB - Day 3

 Dual Boot R-Type 1 & 2 Arcade PCB - Day 3

Here's the circuit I would need to correctly select between two Rom chips - using a single hi/low "game select" signal:

(I made a mistake with my first Rom-select design (The NOT & AND gate thingy) in the first post)..

The /CS (chip select) line on the Roms activates the chip when it goes low..! 

So here, I use two sections of a 74157 to pass either the hi/(active)low /CS signal (or) a 5v signal.

This should correctly disable the unused Rom chip with the positive signal while passing the /CS to the other one.


Just programmed the 27C040 ROMs for C0-3 & N0-3, wired up the A18 address pins to the previous orange wire patch and observed the following:

* R-Type 1 is still fully functional (as expected).
* R-Type 2 has some visual errors, which are related to the extra electronics & board modifications...
** Minor erroneous background tiles.. Not bad, but a few wrong (similar in nature to RT1 prior to the logic/board mods).
** All sprites are a block of solid colour.

So it looks as if I will have to add those multiplexers to switch the modifications in & out.. cool. :)

Also have to do something with the audio Rom.. And since I'm going to use those multiplexers, I think I'll go with the new Rom selection logic above (and be switched with all the other board signals).

Friday, 16 November 2012

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

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

Just performed a simple test of the double sized RT1 & 2 Roms!! :D

Copied all the MajorTitle-RType1 & MajorTitle-RType2 Rom images into a folder & wrote a batch file that did this:

copy /V rt_h0.bin /B + rt2_h0.bin /B combined_h0.bin /B
copy /V rt_h1.bin /B + rt2_h1.bin /B combined_h1.bin /B
copy /V rt_l0.bin /B + rt2_l0.bin /B combined_l0.bin /B
copy /V rt_l1.bin /B + rt2_l1.bin /B combined_l1.bin /B

copy /V rt_n0.bin /B + rt2_n0.bin /B combined_n0.bin /B
copy /V rt_n1.bin /B + rt2_n1.bin /B combined_n1.bin /B
copy /V rt_n2.bin /B + rt2_n2.bin /B combined_n2.bin /B
copy /V rt_n3.bin /B + rt2_n3.bin /B combined_n3.bin /B

copy /V rt_c0.bin /B + rt2_c0.bin /B combined_c0.bin /B
copy /V rt_c1.bin /B + rt2_c1.bin /B combined_c1.bin /B
copy /V rt_c2.bin /B + rt2_c2.bin /B combined_c2.bin /B
copy /V rt_c3.bin /B + rt2_c3.bin /B combined_c3.bin /B

copy /V rt_sp.bin /B + rt2_sp.bin /B combined_sp.bin /B

This copies the R-Type 2 Rom data to the end of the R-Type 1 data & produces files twice the original size.

Which I then burned to four 27C020 EProms (2MBit - instead of the original 1MBit ones)

I added a two pin connector to a capacitor near the main program Roms (H0, H1, L0 & L1),
with this you can select the Hi/Low nedded for the A17 pin that toggles the top & bottom half of the memory (and between the games).

I bent the previously N/C address pin A17 (pin 30) out of the socket on each of the four Roms, then joined them all together with patch wire.. (Bydo Orange!)

With the pin inserted in the ground position, the lower half of the Rom is used & we get R-Type 1:

However when the pin is attached to 5 volts - the top half of the Rom is seen by the board & we should get the beginnings of R-Type 2...?

And............... :O                We do!!! :D

Once the 27C040's arrive.. I'll do the rest of the Roms.. then.. Game on!!

For a Dual-Boot R-Type arcade pcb!! ^_^

Once all the graphics & audio are in working order, I'll evaluate how far I have to go to make the R-Type 1 board modifications (from the original conversion) compatible with R-Type 2..

As I mentioned a couple of days back, I can use TTL Multiplexers to switch the patched & non-patch board signals using the same hi/low signal that selects the Rom halves.

Wednesday, 14 November 2012

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

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

Okay here's the rough plan... :/

Use several  74LS157's (Quad 2-input Multiplexer TTL Logic chips), attach all the patch wires involved in the R-Type 1 conversion into all the 'A' inputs..

Then, connect all the original connections (As in the unmodified R-Type 2 configuration) into the 'B' inputs..

Then join the outputs to the motherboard.. and a switch would be fitted to set either game A (or) B (R-Type 1 or 2).

For the main Rom's... I'll use 27c040's where the 27c020's were (and) 27c020's instead of the 27c010's.

- Then take each Rom-image file from RT1 & RT2 (place them 'end-to-end' RT1 in the lower half of the memory & RT2 in the top half (aligned to the relevant 1/2MBit boundary))

.. Then use the A/B select line used above to drive the upper address pin, which will then allow the mother-board to see either of the games data - as per-normal.
(..grounding the select pin you boot RT1 & setting it to 5v will yield RT2) :D

Then do something similar to the sound Rom /or/ Piggy back another 27512 & monkey with the 'Chip Select' lines.. etc.

Hmm.. 27c040's are quite expensive.. 20 for 60 odd quid on fleaBay!!  :O

Okay.. found 10 for £16.23 .. just hope they are fast enough (nano-second wise).

Sunday, 11 November 2012

Major Title to R-Type 1 Conversion - Day 3

The conversion of Major Title to R-Type 1


Day 3: De-Solder & Replace the N0, N1, N2 & N3 Sprite Roms..


Time to fit the remaining TTL Logic & SRAM chip..

There are several modifications to the motherboard to be carried out in this final section..
Firstly, cut several tracks on the underside of the top-board - here:

And here:

(Looks rough, but that pictures are extremely zoomed in.)

Next-up you have to add the new 74LS32 Quad OR Gate to one of the spare chip 'slots' on the board..

Quite why iRem had added 'unused' spare chip sites to their board is anyones guess.. perhaps they expected to have to bodge the boards post-production?

Either way, they are a welcome coincedence for what we want to do.. the original guide recommends using the chip-site towards the outer corner of the PCB, however my board had an iRem sticker over that one..

So I located the OR-Gate in the next site along:

Next, you piggyback the SRAM & 74LS244 Bus-Tranceiver, like so... taking care to follow the instructions on bending out the correct pins & ensuring the correct chip orientation.

Then all that remains is to just connect it all up with some patch wire.. (just he says)

..and power her up! *drum-roll*

Ta-da! One humanly-affordable R-Type 1 Arcade board \o/

Job done!

Massive thanks and the upmost respect to Paul Swan and Chris Hardy for the original conversion technique.. and for doing all the really hard-work!

And a massive thank you to the various members of the Jamma+ forum who helped make this project possible, particularly; ben76, Jenginner, PaulCan69, Lee-Lee & Vib.

It must be noted that the modification of Major Title to R-Type 2 is a little simpler than the mod above..
(Fewer board modifications are required & you don't need the extra SRAM chip & logic iirc.)

Overall, it took about 22 hours and cost about £20-£30 in spare parts (in addition to the Major-Title board).

That also assumes you already have the tools to hand!.. (I didn't and it ended up being about £150 all-in - still half the price of the original board though!) and most of the time was taken up by de-soldering & chip-extraction (pays not to rush!).. but it should be possible to reduce that given more experience.

Right, I'm off to destroy the Bydo empire..

Saturday, 10 November 2012

Major Title to R-Type 1 Conversion - Day 2.5

The conversion of Major Title to R-Type 1


Day 2.5: De-Solder & Replace the N0, N1, N2 & N3 Sprite Roms..


Okey dokey, just spent 6 hours replacing the remaining 4 Roms.. (N0, N1, N2 & N3)

Pretty much a repeat performance of before.. (shaved 2 hours off the time-tho)
(256 finger-burns & counting..)

Used masking tape as there wasn't much clearance between the chips being removed and the surrounding components.

Also had one dead EPROM in the batch.. but for $7 for 10 second-hand on eBay, it's all good.
(Getting a UV Eraser box soon.)

Once the ROMs were installed, all the game sprites have all appeared on screen & it's looking positive. :)

The backgrounds are still a little broken, but I'm assuming the tracks that are to be cut 'n' patched and the extra logic is Rom addressing related.. and should sort that out.

Hmm, in addition, the back-ground tile layer seems to be missing.. We'll have to see if that comes online once the extra SRAM chip is fitted.

Here's a video of the sprites in action:

Okay.. on to the SRAM & TTL logic chips... Er.. well, maybe not tonight. The frikin' cat's stole my chair.

Major Title to R-Type 1 Conversion - Day 2

The conversion of Major Title to R-Type 1


Day 2: De-Solder & Replace the C0, C1, C2 & C3 Roms..


After sorting the Program & Audio ROMs, I thought I might attempt to remove & socket the four background graphic ROMs on the top CPU board.

Following the advice given by a fellow member of Jamma+, I went straight for the wire cutters... as there was no real need to salvage to original ROMs. (Especially as they were of the PROM type and could not be erased to be re-written.)

The pins were snipped along the edge of the four PROMs as far away from the PCB as possible.

Before de-soldering I've found it's always a good idea to flow some new solder into the joints, just to make sure theres some flux running through to the other side of the board.

Since we are talking about a circuit board more than 20 years old.. I would advise using lead-solder with multi-core flux.

I then used a heated de-soldering pump to remove 90% of the solder.. It's a cheap pump (~£15 in Maplin) and to be fair is a good tool - but the tip is prone to cracking around the tips-edge! :(

Looks like a combination of heat-stress & cheap alloy..

Word of advice - keep the receipt, as you're probably not going to get more that a couple of jobs done before it's knackerd (I'm on my second) - Maplin seem cool with replacing it as they dont sell spare tips.

Finger burning time.. Grabbed each pin (by-hand) from underneath and applied my soldering iron (quickly) in such a way as to touch/heat both the pin & the surrounding pad.

The pins should pop right out (with 128 little finger burns) without tearing any of the pcb contacts off the board.  Not using too much heat, or for too long is important!

Might also be a good time to recommend you use a temperature controlled iron.. ;)

Goodbye Mr Golf game..

I then ran a flux pen over the pads and used de-soldering braid (wick) to suck-up the remaining blobs of solder.

Application of flux really helps you get a good solder flow & you get a satisfying little sizzle when you apply the heat. :)

But.. dont forget to clean the flux off with an isopropyl (rubbing) alcohol soaked cotton bud, as flux is quite corrosive and could potencially eat thru stuff over time.

Not bad for a first attempt..

Just have to fit four 32-Pin DIL sockets & were good to go..!

NOTE: I thought i'd be clever and use turned-pin sockets... Talk about square peg in a round hole! (literally) I spent over an hour just trying to fit the chips into the sockets! while listening to Rom pins going "tink-ta-tink-tink" and have two pins bend under a chip! :(

I know these sockets provide the best connection - but mate this is b*ll*cks! For the other four chips I'm seriously thinking about using the cheaper sockets! Much less stress on the chips and me.

Below is a video of the progress so far: The first part is how the board behaved with just fitting the chips.. (graphics are still a mess), and the second part is how it looked after moving the 3 jumpers on the CPU board (to reflect the change from 1 to 2MBit Roms):

As can be seen, the backgrounds are starting to take shape & it's actually quite playable!

(This was actually the first time I'd performed a major de-soldering job on a double-sided board, it took best part of a day.. and was quite nerve racking.)