27C64 EPROM file data

[Roscoe1017]

I received a file to program a 27C64 EPROM.(see attached)  The file has extraneous data at the beginning of the file and after further investigation it looks like a project file from a TOP type programmer.  The TOP programmer and software do not have good reviews and any attempt to download TOPwin software gives virus warnings.

Any ideas ?

Thanks, Ross

[HwAoRrDk]

Just spitballing here, but I would guess that the actual ROM data is the lines starting with "144", in signed 8-bit decimal format, one line per byte. So, 144 = 0x90, -1 = 0xFF, etc.

[colorburst]

I'd suggest installing the software inside a virtual machine and converting it to a standard format there. Disable its network access in case it does get infected.

[Ian.M]

Just spitballing here, but I would guess that the actual ROM data is the lines starting with "144", in signed 8-bit decimal format, one line per byte. So, 144 = 0x90, -1 = 0xFF, etc.

There's not enough data there for it to be that simple.
A  27C64 EPROM is an 8K x 8 device so 8192 bytes.
Notepad ++ reports 203 lines, and we can see a five line header so there cant be more than 198 lines of data.  Similarly it reports a length of 12288 characters and that it uses UNIX (single LF) line endings. I counted 59 header characters, so the 'payload' can only take 12229 characters.  The data appears to be right justified at four characters per line (what you'd expect for min. width to accommodate -128) so five with the LF, so there cant be more than  2446 data bytes (assuming the final LF is missing).  That's under 30% of the capacity of a 27C64.

The data is unlikely to be compressed due to the presence of a large run of -1, which we believe to be 0xFF, the erased state for an EPROM location.

Unless you know for a fact that the EPROM is blank from address 0x098E upwards, the odds are that this project file does *NOT* contain the EPROM data.

[Shonky]

Run tool in VM or post actual file here. Showing the first 40 lines is not really helpful. Is every line after the header a single 8 bit signed looking number (i.e. -128 to 127)? That's an unlikely way to store an image for programming an EPROM.

I wouldn't trust the 12288 bytes notepad++ reports necessarily but that's exactly 12kB (3 x 4kB blocks size on disk common in Windows). Seems odd from the text based nature of the snippet shown that it's exactly 12kB