From: marc@CAM.ORG (Marc Boucher)
Newsgroups: comp.dcom.modems
Subject: Re: Differences between E and E+... (ROM decoding)
Date: 4 Jan 93 20:26:16 GMT
Organization: Communications Accessibles Montreal, Quebec Canada

dogbowl@dogbox.acme.gen.nz (Kennelmeister) writes:

>mckeeveb@monashee.sfu.ca (Gumby - The unknown user) writes:

>> Well...
>> 
>> Some results are in.
>> 
>> Board differences (Board Rev B for the E, E+): clock speed select switch.
>> 
>> The real difference seems to be in the contents of the EEPROM.  We tried
>> looking at this and discovered that the drain caused by the scope dropped
>> the signal enough to make the modem think it was a non-plus model (on E+).
>> 
>> We're working on decoding the contents... maybe we'll be able to release an
>> 'upgrade ROM' to change at least some of the E's to E+'s...
>> 
>> 'nough said.

>Why ot just ftp the E+ ROMs? They're available readily enough.
>try ftp.csie.nctu.edu.tw for starters - look in the "ZyXEL" directory.

>--
>Alan Brown. (SysAdmin)
>dogbowl@dogbox.acme.gen.nz                      Palmerston North
>Dawghaus BBS -> +64 (6) 357-9245                New Zealand
>             "A wet and windy place in the South Pacific"

Here's a little gift.

/* Convert distributed ZyXEL ROM files to readable form.
   Their encoding is based on special wiring order of PROM data lines to the
   processor: U24 is simply reversed, while U25 seems randomly twisted.

   We just untangle the mess.

   It's written for Unix, but so simple that porting or adaptation to another C
   platform should be easy.

	Enjoy,

	Marc Boucher <marc@CAM.ORG>; Mon Jan  4 1993
*/

#include <stdio.h>
#include <fcntl.h>
#include <malloc.h>

unsigned char inverse[] = {
    0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0,
    0x30, 0xb0, 0x70, 0xf0, 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
    0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, 0x04, 0x84, 0x44, 0xc4,
    0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
    0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc,
    0x3c, 0xbc, 0x7c, 0xfc, 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
    0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, 0x0a, 0x8a, 0x4a, 0xca,
    0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
    0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16, 0x96, 0x56, 0xd6,
    0x36, 0xb6, 0x76, 0xf6, 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
    0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, 0x01, 0x81, 0x41, 0xc1,
    0x21, 0xa1, 0x61, 0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
    0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9,
    0x39, 0xb9, 0x79, 0xf9, 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
    0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, 0x0d, 0x8d, 0x4d, 0xcd,
    0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
    0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3,
    0x33, 0xb3, 0x73, 0xf3, 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
    0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, 0x07, 0x87, 0x47, 0xc7,
    0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
    0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf,
    0x3f, 0xbf, 0x7f, 0xff
};

void
readin(char *fname, unsigned char *loc, int size)
{
	int fd;

	fd = open(fname, O_RDONLY);
	if(fd<0) {
		perror(fname);
		exit(2);
	} else {
		if(read(fd, loc, size) != size) {
			perror(fname);
			exit(2);
		}
		close(fd);
	}
}

void
writeout(char *fname, unsigned char *loc, int size)
{
	int fd;

	fd = open(fname, O_WRONLY | O_CREAT | O_TRUNC, 0644);
	if(fd<0) {
		perror(fname);
		exit(3);
	} else {
		if(write(fd, loc, size) != size) {
			perror(fname);
			exit(3);
		}
		close(fd);
	}
}

#define ROMSIZE (256*1024)

unsigned char u24[ROMSIZE/2], u25[ROMSIZE/2];
unsigned char rom[ROMSIZE], *p;

main(ac,av)
char **av;
{
	char *f;
	int i;

	if(ac!=2) {
		fprintf(stderr, "Usage: %s <release_radical>\n", av[0]);
		return 1;
	}

	f = malloc(strlen(av[1]+5));
	if(!f) {
		perror("malloc");
		return 5;
	}
	sprintf(f, "%s.u24", av[1]);
	readin(f, u24, sizeof(u24));
	f[strlen(f)-1] = '5';
	readin(f, u25, sizeof(u25));

	for(i=0, p=rom; i < ROMSIZE/2; i++) {
		*p    = u25[i] & ((1 << 6) | (1<< 7)); /* d7, d6 */
		*p   |= (u25[i] & (1 << 5) ) >> 1; /* d4 */
		*p   |= (u25[i] & (1 << 4) ) >> 2; /* d2 */
		*p   |= (u25[i] & (1 << 3) ) >> 3; /* d0 */
		*p   |= (u25[i] & (1 << 2) ) >> 1; /* d1 */
		*p   |= (u25[i] & (1 << 1) ) << 2; /* d3 */
		*p++ |= (u25[i] & (1 << 0) ) << 5; /* d5 */
		*p++  = inverse[u24[i]];
	}

	writeout(av[1], rom, sizeof(rom));
	return 0;
}
-- 
^@-------~~--**----/ --- - Marc Boucher
marc@CAM.ORG \----?	":
/-----_--  -    ----_|| +1 514 466 8932 - &-