Can you please advise me as to what the read cycle time of the S4 is when
running in emulation mode?
Dataman do not recommend that you use S4 to emulate anything with access
time shorter than 120 ns.
Can S4 emulate 16 bit EPROMs?
No, S4 cannot emulate 16 bit EPROMs (or any other memories), it is limited
to 8 bit devices only.
Is full, real time emulation possible, i.e are single byte changes permitted
without a CPU reset.
No, S4 cannot do this.
My S4 does not seem to emulate 2716's correctly, why is this?
Due to a quirk in S4's hardware, 2716's must be emulated at address 00800,
rather than 00000. Therefore if you need to emulate 2716's, code must be positioned
at 00800-00FFF. When loading a 2716 to be emulated. The LOAD command can be set
to start loading at 00800. This is achieved be by pressing the up arrow key.
If code is downloaded into S4's RAM, it must be moved to address 00800 prior to
emulation. e.g:
When using the emulation function, the emulation starts only in real time
execution. Do you have in option, a emulation Software or Driver with step command
and trace analysis display?
This is not possible with S4.
When trying to emulate a 29F002B, I get the message:
- >Emulate 29F002B
- (Lower Part Only)
Your S4 is telling you that it does not have enough RAM memory to emulate
this device fully i.e you only have a 128K S4, please upgrade your RAM to 512K,
please contact technical support for more help with this.
I am trying to emulate an H58C256 device, I fill the S4 RAM with my
data and plug it into my application hit EMUL and then apply a reset pulse to my
board, my logic analyser shows the S4 to return FF only.
Hitachi 58C256 is an EEPROM device. So it is essential that you use cable
with DIP28 header (you can put 28 pin socket on DIL32 header of S4 emulation cable).
you should do the following on the S4 side:
- Disconnect wire (or pin) going to pin 27 (WRn pin for EEPROM)
- Disconnect wire going to pin 1
- Connect:
- S4 cable to pin 27
- DIL28 header to pin 1
I am trying to perform ram emulation , the 2716 device is selected on S4
and the green emulation is pressed, the Microprocessor board is switched on, then
the program becomes corrupted. Editing the RAM area of the S4 shows that the data
is meaningless. The Microprocessor system being monitored consists of a Z80 running
at 2MHz addressing two eproms (2716's) and one ram device 6116. The 6116 device
is replaced by the S4 during emulation.
The emulation cable isn't capable of coping with fast memory accesses.
This has nothing to do with the quality of the cable - nothing else would be any
better - the cable impedance is as well matched as possible. It is because the target
system is sending logic signals with fast edges down a long cable. It takes a while
for reflections to settle. So it only works with systems that have long access times.
If the client has a scope he can look at the data coming back And see if it has
settled before the rising edge of the read strobe.
Another point is that the target system must be designed to use the CE and OE as
intended. Access-time starts with a settled address and a valid Chip Enable. The
Read Strobe is usually asserted later, and should be connected to the Output Enable
pin of the Chip being emulated, because that only enables the output buffers (in
S4 or in the chip it is emulating). The data has to become valid before the end
of the read or write strobe. This won't happen unless a valid Address and CE were
asserted before the Read or Write strobe.
The read strobe must not be asserted during a write attempt. In other words the
target must be able to address the emulated memory as RAM. Otherwise there will
be conflict on the data bus - what can also be seen with a scope because the data
doesn't move cleanly from low to high. If it works some of the time then it is timing
or conflict that is the problem.
If the target system is designed correctly and it still doesn't work, then shortening
the emulation lead and write lead will give the cleanest signals. At this point,
if the emulation still doesn't respond fast enough, then slowing the target system
down by dividing the clock is the only remaining possibility.
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