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.