20 Feb
2008
20 Feb
'08
3:40 p.m.
Hi!
Did anyone manage to read out the control-ROM or/and the charakter-ROMs?
In my printer they are Mostek MK2600 types (512 x 8 bit).
Maybe i have to search for the fault of my printer in this IC's :(
But it should be possible to replace them by EPROMs. Accesstime of the
MK2600 is about 700 ns (as i found somewhere on the web) and the slowest
EPROM i found has 400 nS.
I own Data I/O Programer System19 and System 29B, but i found nothing
about the MK2600 in family/pinout lists.
For obvious reasons most programmers do not include mask-orogrammed ROMs
in their list of devices, not even for reading. If you can find a PROM
with the same pinout then you can try reading the ROM as that (but don't
try 'Verify' -- the better programmers do verification at high and low
Vcc which some mask ROMs will not like!).
Hoever, I've generally found it easier not to bother with a programmer
for reading mask ROMs. I find it easier to use a 'User port' on one of my
machines -- somethign like an 8255 card in a PC, or an HP GPIO card in an
HP9000/200, or... Put the chip on a solderless breadboard or similar,
wire the address pins to output lines of the user port and the data pins
to inputs. Do the approriate thing with the enable pins (you can normally
have the ROM enabled all the time for this). Then writie a trivial
program to cycle through all the addresses, read in the data, and store
it.
-tony