This page is under construction. Details are added as time and interest permits it.

Yet another computer museum
Making PX-8/PX-4 ROMs

For more info on the PROM structure see the PROM data page.

Making ROMs like the B: and C: disk isn't very difficult. For this you need:

• A Epson PX-8.
• Access to a PROM programmer.
• A cable to connect the PX-8 to the outside world.
• EPROMs of the appropriate type.
• Optionally, cradles to insert the EPROMs into, to plug them in the PX-8 sockets.

The software to create the PROM contents is provided by EPSON. Two versions exist "PROMFO.LBR", which contains PROMFO.COM and several docs, and "PXPROM2.ARC".

PROMFO.COM is version 1.0 of the program, is 7 kByte and not completely bug free (see the doc that comes with it).

PXPROM2.COM is version 2.0, is 28 kByte and supports extra PROM configurations. There are issues with the ROM images created with this program. At least the 32 kByte sized files have an incorrect layout, the directory should start at 0x4000, not at 0x0000.

PROMFO.COM is for creating PX-8 ROMs only, or format 'M' (from maple). PXPROM2.COM can create both formats supported by the PX-4, 'M' and 'P' (from pine). The 'M' format is strictly a disk image format, the 'P' allows execution of programs directly from the ROM without loading it in RAM. The PX-4 BASIC ROM is an example of the 'P' format. These programs have a special header and do not load and execute from 0x100.

The 'M' format allows double ROM images, spanning the disk image over two ROM capsules.

Both programs were found at Cereal Port BBS. For a local download, see below.

Configurations supported by PROMFO (1.0, 11/29/83):

• Functions: format/write, compare, ROM capsule directory
• Output device: FDD, PROM Writer, microcassette
• PROM type: 64kx1, 64kx2, 128kx1, 128kx2, 256kx1 (resp. 8KByte, 2*8KByte, 16kByte, 2*16kByte, 32kByte)

Configurations supported by PXPROM2 (2.0, 07/31/84):

• Formats of PROM: M(aple),P(ine)
• Output devices: FDD, RS-232C
• PROM types (M format): 64kx1, 64kx2, 128kx1, 128kx2, 256kx1, 256kx2 (resp. 8KByte, 2*8KByte, 16kByte, 2*16kByte, 32kByte 2*32kByte)
• PROM types (P format): 64k, 128k, 256k, 512k, 1M (resp. 8KByte, 16kByte, 32kByte, 64kByte, 128kByte)
  (last two are for the multi function unit only and PX-4 External Ram Disk)

For unarchiving *.LBR or *.ARC see Archiver overview

• PROMFO
• PXPROM2

At WEB G is a Turbo Pascal source claiming to create PROM images, but this doesn't work for the 32kByte images for the B: and C: drive. The program compiles clean, but the images generated are incompatible (No header, and the directory at 0000h instead of 4000h. This is OK for 8k Byte and 16 kByte ROMS but incorrect for 32 kByte ROMs). It is still available from usenet/Google newsgroups (or serach for epson rom generator group:comp.os.cpm).

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Latest update: 2010-05-21

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