Friday, 9 November 2012

Major Title to R-Type 1 Conversion - Day 1

The conversion of Major Title to R-Type 1


A top bloke ben76 over on the Jamma+ site brought my attention to a modification devised by Paul Swan and Chris Hardy to convert an iRem Major-Title arcade PCB to run either R-Type 1 or 2.

With the original PCB of R-Type 1 costing upwards of £2-300 a conversion of the much cheaper golf board is very attractive.. and just had to be attempted.

Major Title runs on an iRem M84 pcb, while R-Type 1 runs on an M72 board and R-Type 2 on an M82.

They all appear to have quite similar hardware, give or take a tile-layer.. and there appears to be some memory and addressing differences.  The work of Paul & Chris bridge these gaps by way of a new set of program ROM's and a set of physical board modifications & additions to be carried out.

The original modification guides can be found below:

Major Title to R-Type (M72) Conversions
Major Title to R-Type 2 (M84) Conversions

Major respect to these guys, this couldn't have been easy to fathom at all! A serious understanding of the hardware and game code must have been needed to pull this off! Hat's off to you indeed! with guide in hand, several ingredients are needed:


  • 1 x iRem Major Title arcade board:

  • 1 x 27512 EPROM
  • 9 x 27C010 EPROMs
  • 4 x 27C020 EPROMs:

  • An EPROM Programmer capable of writting the above:

  • 9 x 32-Pin DIL socket
  • 1 x 28-Pin DIL socket

  • 1 x HM62256-12 (or equiv.) SRAM chip:

 And a pair of 74 series TTL logic chips:
  • 1 x 74LS244 Tri-State Octal Buffer / Line driver chip
and an:
  • 1 x 74LS32 Quadruple 2-Input Positive-OR Gate chip 

Day 1: Replace the L0, L1, H0, H1 & SP Roms.

The first step was to burn a new set of program ROMs, as these were socketed it seemed like the first port of call..

Four 27C010's were programmed with the data for the L0, L1, H0 & H1 chips (which contain the code for the V30 CPU).
At that point I decided to power up the board, just to see how far it would work..

Happy days indeed! :D

While the sound & graphic data was garbage (the rest of the ROM's still held the Major Title data), R-Type can clearly be seen to be running!

The next easy step was to replace the 27C512 (SP) EPROM holding the sound code:

Once this was done, the sweet sound of R-Type filled the air! :)

Next stop, de-solder the remaining chips and fit the sockets..