Yep. If there /is/ anything on either of those that I'm missing, let me know, but I swear I've looked. So here's a semi-stupid question; having just acquired a Data I/O EEPROM programmer which is also fairly adept at dumping EEPROMs, is it possible to use the Data I/O to dump the VT100 rom in question? That is, if I choose a PROM or EEPROM type that's compatible with the type of ROM in use on the VT100 board, is it likely that I'll be able to read it on the programmer like a standard PROM/EEPROM? I'm kinda new at this particular corner of the hardware field so I have no idea... can someone set me straight? Thanks, Josh Richard wrote:

Dave McGuire wrote: Groovy. So the ROM in question is a Signetics (I believe) 8228; how do I go about determining what EEPROM is equivalent? Is there a decent reference guide for this sort of thing? Thanks, Josh

On Nov 30, 2007 1:06 AM, Josh Dersch <derschjo at msu.edu> wrote: The 8228 is a 1024x4 ROM. There is a standard character generator ROM N82281-CB162 which has a pattern listed in a Signetics data book. It's only 64 characters, upper case only in the standard ROM. -Glen

Simpler, perhaps - but, I believe, wrong. Consider this quote: The VT220 display was refreshed at 60 Hz, which is slow by today's standards. This slower refresh rate required a slower phosphor on the CRT, or users would notice flickering. However, slower phosphor means slower to light up as well as slower to fade, and this slow rise time would make single pixels almost invisible. The first two sentences are fine, as is the first half of the last sentence, but the second half of the last sentence is wrong. It's confusing two different rise times. In each case there is an input step signal and a somewhat smoothed output signal whose rise time is of interest, but they are totally different. In one case, the input is electrons hitting the phosphor and the output is light generated. In the other case, the input is the signal from the character generator circuitry and the output is the voltage controlling the intensity of the electron beam. The former is related to phosphor persistence; the latter is related to how much smoothing is inflicted on the signal by certain pieces of circuitry and has nothing whatever to do with phosphor - indeed, it can be applied to any amplifier or transmission line. Stating that there is a direct causal link between them, as the part of the above quote after the last comma does, is just _wrong_. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse at rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

Glen Slick wrote: I tried to dump the ROM over the weekend and had no luck whatsoever, regardless of what I tried to read it as. I suppose it wouldn't be out of the question to recreate the contents manually based on the patterns tedious :). I'm doing a software emulation of the VT100 hardware, so that at last a "100%" compatible VT100 emulator will be available for the PC :). I have the 8080 emulation done, and once I get some time it's a matter of getting the video and I/O emulation working... I plan on making the I/O "pluggable" so you can use the emulator to talk to a serial port, telnet, ssh, standard IO, etc... Josh