Hayes Smartmodem 1200 firmware dumped:

[Joseph Zatarski]

Hello again Everyone,


Last night my roommate and I worked on dumping the Hayes Smartmodem 1200 
firmware so that we could attempt a repair on another modem. This other 
modem had a dead EPROM, a dead ROMless Z8, a dead CD4069, and a dead 
'SR0075' (custom marked Hayes part with Zilog logo on it).


As it turns out, the SR0075 is a Z8 with 2kB of mask ROM. Attempts to 
read it like an OTP/EPROM part did not work, however were were able to 
put it in test mode, as detailed on page 363 of 
http://www.textfiles.com/bitsavers/pdf/zilog/z8/Z8_Family_Design_Handbook_Jun88.pdf


By doing so, we were able to execute some simple code which read every 
byte of the internal ROM and dumped it to memory address 0xAAAA, which 
we then recorded with a logic analyzer to create the dump of this Z8.


The files are attached to this email, and it'd be nice if they were 
archived somewhere. Maybe somewhere in bitsavers, if Al could help us 
out with this. One file is the internal Z8 ROM, and the other is the 
2764 that goes with the ROMless Z8.


Best Regards,

Joe Zatarki