P5 = HM6116P-4 (2K*8 static RAM)
P6 = 2003
P7 = NEC uPD8039LC (8bit CPU, 27 I/O Lines, 128 bytes RAM, 2048 bytes ROM)
8039 Details:
MCS-48 family of 8-bit microcontrollers,
* Seikosha GP500A - Was offered as '''Seikosha GP500A''' for general purpose (centronics port)
* Seikosha GP500AS - Was offered as '''Seikosha GP500AS''' for general purpose (serial rs232 port)
* Seikosha GP500M-2 - Was offered as '''Amstrad DMP1''' for CPC (centronics 36pin port) (plus 2K SRAM) (BIOS: 8DE-1)* Seikosha GP500VC - Was offered as '''Commodore MPS-801''' for VIC20 and C64 (commodore 6pin serial port) ([[Media:Commodore MPS801 Printer Manual.txt|manual]]) (90-byte buffer, no 2K SRAM)* Seikosha GP500AT-1 - Was offered as '''Atari 1029''' for Atari XL (dual 13pin port) ([[:File:Atari1029 Printer.jpg|printer photo]], [[:File:Atari1029 PCB.jpg|pcb photo]]) (no 2K SRAM) (BIOS: 8AT-1)
The main difference is that the PCBs are customized - the VC and AT models have non-centronics connectors. The ROMs might be also customized, possibly containing different character sets (?), and most probably different protocols (for the serial-port VC version at least).