Yamaha DSR-1000

Chip: NEC upD27C1000D-20 with customized active-high OE (pin24) polarity
CPU: HD63B01YP

Used are only 64kbytes, since pin2 (a16) is tied to gnd on the pcb.
In the synth, first 64k part of the rom contents get repeated for the upper 64k.
Pinout on the pcb is designed for mask rom with slightly different pinout, so
use of only the lower 64kbytes of smallest 32pin uv-erasable rom seems to be
some sort of compromise they had to make.

Sticker:
~~~~~~~
 XD178
  E 0
~~~~~~~

E0 = E00 = actual rom version is 5.

7-segment display characters are at $9acf.

Reset vector(s) in the end point to the $8000 where the code starts.

Memory mapping in the synth is:
8kbytes IO
8kbytes SRAM1
8kbytes SRAM2
8kbytes paged access into entire ROM
32kbytes unpaged access to upper 32kbytes of ROM


Edward dtech
www.dtech.lv
